DVolume 26, No. 4 SJanuary-February 2021 For Private Ciruculation Only
TIMES
Lorem ipsum
Highlights
Glaucoma Issue
Post Keratoplasty Glaucoma
Target IOP in different
Glaucomas, Adult and Pediatric
Role of meditation an
adjunctive therapy in Glaucoma
Minimally Invasive Glaucoma
Surgeries ( MIGS) :
A Revolution in Glaucoma
Surgery
Official Bulletin Magazine of
DELHI
OPHTHALMOLOGICAL
SOCIETY
Contents
Editorial 48 UBM Imaging and Glaucoma
59 Developmental Glaucoma
05 Prof. (Dr.) Namrata Sharma 67 Anterior Segment Optical Coherence
Hony. General Secretary
Tomography (ASOCT) for Evaluation of
06 Dr Jatinder Singh Bhalla Filtering Bleb
Treasurer DOS 70 Bleb needling: Effective safe procedure to revive
failing bleb
Subspecialities 74 Use of Artificial Intelligence in Glaucoma
83 Glaucoma and Myopia
Glaucoma 87 Ocular Perfusion Pressure: Bridging the gaps in
Glaucoma Management
07 Post Keratoplasty Glaucoma 96 Clinical Trials in Glaucoma
12 Target IOP in different Glaucomas, Adult and Pediatric 104 Newer advances in Glaucoma Diagnosis and
17 Role of meditation an adjunctive therapy in Glaucoma Management
19 Minimally Invasive Glaucoma surgeries ( MIGS) : A 111 Trabeculectomy: Tips for Better Outcomes
Revolution in Glaucoma Surgery DOS Quiz
25 Lasers in Glaucoma
23 Role of Lens Extraction in Primary Angle Closure 117
Disease Tearsheet
38 Burden of Glaucoma in India
43 Clinical Pearls for Glaucoma Management in some 119 Malignant Glaucoma
Special Situations
DOS Executive Members 2019-21
DOS Office Bearers
Dr. Subhash C Dadeya Dr. Pawan Goyal Dr. Namrata Sharma Dr. Hardeep Singh
President Vice President Secretary Joint Secretary
Dr. Jatinder S Bhalla Dr. Vinod Kumar Dr. Manav Deep Singh
Treasurer Editor Library Officer
Executive Members
Dr. Dewang Angmo Dr. Jatinder Bali Dr. Shantanu Gupta Dr. C. P. Khandelwal
Dr. Rahul Mayor Dr. Vipul Nayar Dr. Rajendra Prasad Dr. Kirti Singh
DOS Representative to AIOS Ex-Officio Members
Dr. Jeewan S. Titiyal Dr. M. Vanathi Dr. Rakesh Mahajan Dr. Arun Baweja
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 03
Volume 26, No. 4, January-February 2021
DOS Times Editorial Board
Editor In Chief Editorial Board National Board
Namrata Sharma
Dr. Atul Kumar Dr. Parul Icchpujani
Editor Dr. Aniruddha Maiti Dr. Ronnie George
Prafulla Kumar Maharana Dr. Apporva Ayachit Dr. Sushmita Kaushik
Dr. Jitendra Jethani Dr. Gopal Pillai
Assistant Editors Dr. Mita Joshi Dr. Usha Singh
Dr. P. Dutta Majumdar Dr. Subhendu Boral
Dr. Noopur Gupta Dr. Meena Chakrabarti
Dr. Brijesh Kakkar Dr. Raksha Rao
Dr. Digvijay Singh Dr. Kumudini Verma
Dr. Ritika Sachdev Dr. Rashmin Gandhi
Dr. Dewang Angmo Dr. Siddharth Kesarwani
Dr. Rebika Dr. Chaitra Jayadev
Dr. Saurabh Sawhney Dr. Bibhuti P. Sinha
Dr. Reena Sharma Dr. Amit Porwal
Dr. Rajat Jain Dr. Prashant Bawankule
Dr. Jaya Gupta Dr. Arvind Kumar Morya
Dr. Anita Ganger
Ritu Nagpal Sahil Agarwal Dr. Umang Mathur
Dr. Neera Agarwal
Gunjan Saluja Deepali Singhal Dr. Poonam Jain
Dr. Manisha Agarwal
Dr. Hardeep Singh
Dr. Anita Sethi
Dr. Tushar Agarwal
Dr. Rohit Saxena
Dr. Swati Phuljhele
Dr. Vivek Dave
Dr. Mohita Sharma
Dr. Rajesh Sinha
Dr. Ritu Arora
Dr. P.K. Pandey
Dr. H.K. Yaduvanshi
Dr. O.P. Anand
Mohamed Ibrahime Asif Rahul Kumar Bafna
Sohini Mandal Prakhyat Roop
Editorial
From the
Editor Desk
“Change is the only constant in life”
Prof. (Dr.) Namrata Sharma Respected Seniors and Dear Friends
(MD, DNB, MNAMS) The field of glaucoma has witnessed lot of changes in the past decade in terms of
better understanding of pathophysiology of various glaucomatous disease, the
Hony. General Secretary role of various imaging modalities for the diagnosis and monitoring of glaucoma,
Delhi Ophthalmological Society realisation of some important related aspects such as meditation and artificial
intelligence, understanding of genetic aspects, upcoming of new anti glaucoma
Cornea, Cataract & Refractive Surgery Services medications and heading towards minimally invasive surgeries. All this translates
Dr. R.P. Centre for Ophthalmic Sciences, to better opportunities for clinical and molecular research and eventually better
All India Institute of Medical Sciences (AIIMS) patient care.
New Delhi
“Glaucoma” is one of the leading causes of irreversible vision loss. About 3.6
million blind people, aged 50 years or older were attributed to glaucoma, in the year
2020. Globally, this was second highest, following people becoming bind due to
cataract. A lot of emphasis therefore has been on “screening of glaucoma” to detect
it in its initial stages,. Since the disease runs an asymptomatic course, its not very
uncommon to see patients presenting for the first time in the advanced stage. Early
Diagnosis and timely initiation of appropriate therapy is the key to successfully
prevent it from progressing to an irreversible stage.
This special issue of DOS Times on the subspecialty “Glaucoma” includes articles
based on some of the pertinent topics of the subject such as the “target IOP”, “ocular
perfusion pressure”, “minimally invasive glaucoma surgeries”, role of “artificial
intelligence” and “meditation” as an adjunctive therapy. It also covers articles on
the role of imaging modalities in glaucoma evaluation, important clinical trials,
glaucoma in association with special situations such as following keratoplasty and
malignant glaucoma. Our aim is to keep the readers well versed and updated with
the upcoming developments in their respective sub-specialities, thereby helping in
improved patient care.
I wish all of you a pleasant reading.
Prof. (Dr.) Namrata Sharma
(MD, DNB, MNAMS)
Hony. General Secretary
Delhi Ophthalmological Society
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 05
Guest Editorial
Guest
Editorial Desk
Knowing is not enough, we must apply.
Willing is not enough, we must do.
Dear Colleagues, Dr Jatinder Singh Bhalla
Treasurer DOS
It is my great pleasure to share with you the Glaucoma issue of the DOS Times. The learning
in field of Glaucoma has undergone a significant transformation in the past few years. The HOD (Department of
current issue has views & pearls of wisdom from Leading Glaucoma Experts from across Ophthalmology), DDU Hospital,
the country .
New Delhi 110058
There has been addition of newer drugs ,surgical & Laser procedures in the armamentarium
to treat Glaucoma.The concept of target pressure has been lucidly explained.With advent
of MIGS, while many predicted the demise of trabeculectomy, it still remains preferred go-
to procedure for patients with advanced or rapidly rogressing disease who fail maximal
medical therapy, particularly those who need very low intraocular pressures (IOPs). There
is no novel operation on the near horizon that will allow us to titrate IOPs to this very
low range for a substantial proportion of those undergoing surgery.Lasers in Glaucoma
& Glaucoma Progression has been nicely covered .The concept of meditation to treat
Glaucoma is a novel & interesting concept. We also have article on clear lens extraction that
underscores the present accepted status. Article on Glaucoma management in pregnancy is
meant to present a practical approach and to serve as a quick reference guide .This issue also
covers topics on OCT & OCT- A, that are big innovations in field of Glaucoma.
The number of publications describing AI & deep learning in glaucoma has increased
rapidly. Deep learning is well suited to help us with the identification of glaucoma and its
worsening. Current challenges include generating sufficiently large, labeled data sets and
understanding which deep models are best suited to our needs.
Last but not the least , I must take this opportunity to express my sincere gratitude to all the
contributing experts for their valuable support in bringing out this special issue .
I wish you all a pleasant reading .
Dr Jatinder Singh Bhalla
Treasurer DOS
HOD (Department of Ophthalmology), DDU Hospital,
New Delhi 110058
06 DOS Times - Volume 26, Number 3, November-December 2020 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Post Keratoplasty Glaucoma
Rinky Agarwal1, MD, DNB, MNAMS, Ritu Nagpal2, MD, Rahul Bafna2, MD,
Namrata Sharma2, MD, DNB, MNAMS
1. Dept of Ophthalmology, Saraswati Institute of Medical Sciences
2. Dept of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences
Introduction Corneal pathologies with opacification a. Preoperative: Corneal dystrophies
Post-keratoplasty glaucoma is a serious affecting only the stromal layers and keratoconus have a lower
and sight-threatening complication and are subjected to ALK. Endothelial risk of glaucoma than bullous
is associated with significant ocular keratoplasty (EK) usually involves keratopathy, anterior segment
morbidity.1,2 Increased intraocular removal of unhealthy host Descemet’s trauma, iridocorneal endothelial
pressure (IOP) after any keratoplasty membrane (DM)-endothelial complex syndrome and corneal perforations,
procedure can accelerate the rate of (DEC) and insertion of donor DEC with particularly bacterial ulcers. Repeat
donor endothelial cell loss and graft or without overlying stroma in DSAEK grafting, presence of preoperative
failure, besides inciting an early graft (Descemet membrane automated glaucoma or IOP >20 mmHg or
rejection. The incidence reported is endothelial keratoplasty) and DMEK filtering surgery before keratoplasty
highly variable and numerous etiologic (Descemet membrane endothelial also increases the risk.
factors have been associated with this keratoplasty) respectively. EK is
type of secondary glaucoma. While, commonly indicated for endothelial b. Intraoperative: IOL exchange
the management options range from dysfunction and offers faster recovery, or removal during surgery,
conservative to surgical depending on and lesser suture-related complications concomitant vitrectomy and
its severity. The purpose of the present when compared to PKP. filtering surgery increase the risk
discussion is to highlight the incidence,
etiology, and management of glaucoma A. Glaucoma following c. Postoperative lens status: The risk
following different corneal transplant of glaucoma is as follows: aphakia>
procedures. Penetrating Keratoplasty anterior chamber intraocular lens
(AC-IOL) > posterior chamber
Types of keratoplasty The incidence of glaucoma following intraocular lens (PC-IOL) > phakic
PKP varies between 9 to 50%, and eyes
procedures ranges from 10 to 31% in the early
post-operative period and from 18 to Pathogenesis
Different types of corneal transplant 35% in the late post-operative period. The pathophysiology of post-PKP
techniques include lamellar and full- The variability in incidence is partly glaucoma is multifactorial and may
thickness keratoplasty. Penetrating attributed to the different manner in depend on the time of occurrence after
keratoplasty (PKP) involves which glaucoma is defined in various surgery (early-onset or late-onset).
replacement of the full-thickness host studies. According to Borderie et al, the
cornea by an analogous donor tissue 10-year probability of visual loss related a. Early-onset glaucoma
and patients having opacification to glaucoma was 1.0% after EK, 2.1%
involving all layers of the cornea are after ALK, and 3.6% after PKP.3 Retained Viscoelastic substance
subjected to PKP. Contrastingly, only (VES): High viscosity VES, if
partial replacement of the diseased Risk factors retained in the anterior chamber
corneal layers is undertaken in lamellar (AC), can lead to trabecular
keratoplasty. In anterior lamellar Knowledge of the risk factors is meshwork (TM) obstruction, thus
keratoplasty (ALK), the affected important for its effective prevention, hindering aqueous humor outflow.
superficial and/or deep stroma is diagnosis, and early treatment. This
exchanged for an anatomically similar may increase the chances of success of Suturing technique: Reduction
donor in superficial ALK (SALK) the corneal graft. Various risk factors of the aqueous outflow occurs
or deep ALK (DALK) respectively. associated with secondary glaucoma with deep, midstromal, or tight
after PKP include: sutures (widen posterior wound
gape), lengthy sutures (excess
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Subspeciality-Glaucoma
compression of the tissues), large host junction can lead to shallow Management
grafts and thick peripheral corneas. AC), atrophic or floppy iris, prior
iridocorneal adhesions or persistent a. Prophylaxis
Postoperative inflammation: postoperative inflammation and
Breach of blood-aqueous barrier less likely with an oversize margin To prevent worsening of glaucoma
after surgery may result in of the donor bed (≥1 mm). post PKP, any pre-existing
exaggerated inflow of inflammatory glaucoma should be well controlled
cells and normal serum components Distortion of the angle with prior to the surgical intervention,
into the aqueous humor. These can collapse of TM: Elevated IOP either by medical or surgical
impede the outflow by blocking following PKP in an aphakic patient means. Whenever necessary,
the TM. Additionally, fibrin-rich may be due to angle distortion intraoperative synechiolysis, or
exudates can cause secondary secondary to compression of angle iris suturing/ iridoplasty must be
angle-closure glaucoma by forming structures. While phakic eyes suffer undertaken for PAS or floppy iris
peripheral anterior synechiae (PAS) weakening of only the anterior respectively. Maintaining adequate
or posterior synechiae. support after surgery, aphakic graft-host disparity (at least 0.5mm)
eyes are vulnerable to lack of both and following appropriate suturing
b. Late-onset Glaucoma anterior and posterior support techniques (short and equal
to angle structures. Post-surgical sutures avoiding iris incarceration)
Corticosteroid induced edema and inflammation further should be undertaken to prevent
glaucoma: Prolonged use of compromise the TM function. further PAS formation. VES should
corticosteroids for preventing graft Other factors that contribute to be removed as completely as
rejection makes certain patients angle distortion include tight possible at the end of the surgery.
with steroid responsiveness more suturing, long bites, larger trephine In the immediate postoperative
vulnerable to IOP elevation. sizes, smaller recipient corneal phase, frequent instillation of
Steroids are postulated to diameter, and increased peripheral corticosteroids helps in reducing the
cause water retention, stabilize corneal thickness. risk of PAS formation by controlling
lysosomal membranes, cellular inflammation. However, in the
proliferation and deposition of Other causes: Other speculated long-term, efforts should be made
extracellular matrix material, causes include pupillary blockage, to maintain graft survival with the
and inhibit phagocytic properties lens induced glaucoma, and least clinically feasible dose and
hyphema. frequency of steroids to reduce the
in the TM. This promotes risk of steroid-induced IOP spike.
IOP measurement and clinical
accumulation of cellular debris assessment after PKP b. Medical treatment
and mucopolysaccharides in the
TM thus leading to its narrowing Reliable postoperative assessment Anti-glaucoma agents represent
of IOP, disc, and visual field changes the first line of therapy for
and mechanical obstruction. following PKP may be precluded treating post-PKP glaucoma. These
by constant alterations in corneal include topical drugs such as
Corticosteroids also exert thickness, astigmatism, and refractive beta-blockers, alpha-2 agonists,
their glaucomatous effects by status of the patient. High astigmatism, carbonic anhydrase inhibitors
influencing specific genes such as graft edema, thick fluorescein (CAI), prostaglandin analogues and
meniscus and inappropriate mires miotics, as well as systemic CAIs.
myocilin (formerly known as TM- make Goldmann applanation The choice of therapy depends on
tonometry (GAT) practically its efficacy and the effect on graft
inducible glucocorticoid response impossible in post-PKP patients. In survival and on the patient’s quality
[TIGR]) gene. The frequency of these eyes, Mackay-Marg electronic of life.
IOP rise is more pronounced applanation tonometer, the Tonopen,
with dexamethasone than or the dynamic contour tonometer While beta-blockers can be
(DCT) can be used to measure IOP. utilized for controlling IOP in the
fluoromethasone and medrysone, The use of a pneumatonometer and perioperative period, as well as for
and in patients with keratoconus frequency-doubling perimetry, which long-term therapy, these can cause
and Fuchs dystrophy. Although are independent of postoperative punctate epithelial keratopathy
topographic changes of the cornea, can and corneal anaesthesia with
dexamethasone 0.1% has a higher be helpful supplemental methods to prolonged use. Alpha-2 agents,
potency and half-life compared detect early glaucomatous damage in although, efficient in controlling
to prednisolone acetate 1%, the these patients. IOP rise, can lead to ocular allergies
latter exerts a stronger ocular in around 1/3rd patients. The use of
hypertensive effect because of its
superior corneal penetration.
PAS formation: It is more likely
with shallow AC (preoperatively
perforated cornea or
postoperatively wound dehiscence
or iris incarceration at the graft-
08 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
adrenergic agents like epinephrine, by multiple prior interventions) and elevated IOP in the post-operative
and dipivefrin is discouraged in the presence of PAS that make the period (36.1% by Huang et al), the
functioning of the fistula difficult. incidence of de novo glaucoma ranges
the modern-day management of The failure rate is further increased from 0% to 9%. Around 11% cases of
these patients because of their in aphakic eyes where a vitrectomy is raised IOP occur within the first week of
required to prevent vitreous tissue from surgery.4 Considering the low incidence
potential corneal epithelial blocking the trabeculectomy ostium. of post-surgical glaucoma following
Although use of antimetabolites such DALK, cornea surgeons should prefer it
toxicity, exacerbation of cystoid as Mitomycin C and 5-Fluorouracil over PKP, whenever feasible.
may increase the success rate of
macular edema, and conjunctival filtering surgery by preventing Risk factors
fibroblastic response, chances of Patients with history of allergic eye
inflammation. Prostaglandin choroidal detachment, macular edema disease and use of topical patanol 0.1%
and fistula formation increase with or ciclosporin (of any concentration)
analogues are preferable for chronic their application. It should also be before surgery and use of topical
remembered that trabeculectomy prednisolone acetate 1% compared to
forms of post-PKP glaucoma as surgery can compromise graft clarity dexamethasone 0.1% after surgery are
and function precipitates by promoting associated with higher rates of elevated
their effect installs relatively donor endothelial cell loss. IOP after surgery.
slowly. They may be associated Artificial glaucoma drainage devices Pathogenesis
Inserting an artificial glaucoma Pupillary block can occur either due to
with cystoid macular edema drainage device (GDD) may be intracameral seepage of air through TM
more successful than conventional when performing big bubble technique
and are preferably avoided for trabeculectomy in controlling IOP or due to entrapment of air behind the
post PKP due to the posterior location iris. Other causes of raised IOP include
herpetic keratitis, because or risk of of the filtering bleb in the former that swollen grafts and corticosteroid
avoids perilimbal fibrosis. However, its response.
recurrence. Topical CAI can result insertion is more expensive, requires a
higher surgical experience and carries Management
in endothelial decompensation a relatively higher risk of graft failure. Acute rise of IOP due to pupillary
The proposed mechanism may be either block can be reversed by pupillary
and subsequent corneal edema in immunological (tube allows conduit dilation, topical 1% apraclonidine and
for retrograde passage of inflammatory oral acetazolamide orally, and laying
eyes with borderline endothelial cells into the AC, that can lead to graft the patient down in a supine position
rejection) or mechanical (displaced for 1 to 2 hours. Within 1-2 days, the
function. While systemic CAIs tube can rub graft endothelium). air bubble usually diminishes in size.
However, if no relief occurs, urgent
can cause paraesthesia, tinnitus, Cyclodestructive procedures release of excess intracameral air must
Cyclocryotherapy and cyclophotoco- be undertaken. Management of chronic
fatigue, muscular weakness, agulation (diode laser, Nd:YAG laser, glaucoma is undertaken in same lines as
transpupillary argon laser or endoscop- that of PKP.
nausea, depression and cutaneous ic) are usually employed for treatment
of refractory or intractable post PKP C. Glaucoma Following DSAEK
allergies. These are very useful in glaucoma. They are a useful modality to The incidence of secondary glaucoma
control IOP in eyes with severe conjunc- post DSAEK is reported to be between
the treatment of sudden IOP spikes tival scarring and poor visual potential. 0% and 18%. The overall incidence
However, these carry a high risk of graft is lower, less severe, and with better
in the immediate postoperative failure, hypotony and, phthisis bulbi. outcomes than that of post PKP
glaucoma.
period. B. Glaucoma Following
Deep Anterior Lamellar Risk factors
In cases of steroid responsive Keratoplasty Presence of prior glaucoma and pre-
glaucoma, the frequency of topical existing glaucoma surgery are risk
steroid may be tapered to the Although DALK may be associated with factors.
minimum required. Alternatively, a significant incidence of transiently
stronger steroids such as
prednisolone or dexamethasone can
be replaced by weaker steroids such
as fluorometholone, loteprednol,
and rimexolone. If needed, topical
cyclosporine A 0.5–2.0% can be
added to prevent graft rejection.
c. Laser treatment
Although Nd:YAG laser iridotomy
(for pupillary block glaucoma),
iridoplasty and argon or selective
laser trabeculoplasty can be used
to control IOP in certain cases,
poor visualization through opaque
peripheral host cornea limits its
application in majority of the cases.
d. Surgical treatment
Trabeculectomy
Standard trabeculectomy has a low rate
of success after PKP due to extensive
subconjunctival fibrosis (induced
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Subspeciality-Glaucoma
Pathogenesis been reported to be 2.7%. According paracentesis. In eyes without a history
to Maier et al, 15.4% of post-DMEK of prior glaucoma, postoperative
Early postoperative rise of IOP rise can patients develop ocular hypertension glaucoma may be avoided by adequate
occur due to pupillary block. Although within first 24 hours after the management of air bubble, a titrated
larger air bubble minimizes the risk procedure.5 However, persistently high steroid regime and proper graft
of graft detachment in EK, excess IOP is estimated to happen in 12.5% of positioning.
intracameral air increases the risk of patients only.
posterior pupillary block by blocking F. Glaucoma Following
the peripheral iridectomy (PI, usually Risk factors Keratoprosthesis
made inferiorly). A superior PI can be
blocked by a small air bubble if patient Patients with pre-existing glaucoma The prevalence of glaucoma in patients
adopts an upright position immediately and those undergoing concomitant undergoing keratoprosthesis (KPro)
after surgery. An air bubble trapped in cataract surgery and IOL implantation placement ranges from 36 to 76%. De
the posterior chamber can push the tend to have higher incidence of novo glaucoma has been reported to
iris anteriorly thereby compressing the postoperative IOP spikes.6 Incidental occur in 2–28% of patients.
iridocorneal angle and obstructing the cases may be related to the presence of
aqueous flow. Development of PAS, an angle-supported phakic IOL or PAS Risk factors
angle distortion, prolonged steroid use, with a decentered graft. Preexisting glaucoma is a risk factor.
and inflammatory response may be
associated with chronic rise of IOP. Pathogenesis Pathogenesis
As most KPro recipients have
D. IOP Measurement The most frequent cause of post DMEK undergone prior PKP, they usually
Following DSAEK glaucoma remains steroid-induced IOP have some amount of preexisting
elevation. Similar to DALK and DSAEK, synechial angle closure and further
The current gold standard of IOP air bubble-induced angle closure angle closure after KPro may perpetuate
measurement, GAT is calibrated for a can occur in immediate post-DMEK secondary glaucoma. AC angle can also
mean corneal thickness of 520μm and period (mostly within first 2hours of be compromised by the large backplate
the increased corneal thickness post surgery), particularly in phakic eyes. of KPro if it placed in close proximity
DSAEK may affect the accuracy of Similar to PKP-induced glaucoma, to the iris, in aphakic individuals or
its measurements. Performing a DCT retained VES can also cause rise of when iris is removed for achieving
and pneumotonometry that assess IOP. Multiple mechanisms including a monocameral eye. Use of topical
IOP independent of corneal thickness, increased inflammation, altered angle steroids for prolonged periods to
curvature, and hydration may be anatomy, and presence of a flexible control inflammation following KPro
additional useful methods in such cases. IOL-iris diaphragm in pseudophakic implantation can further lead to steroid
eyes may be responsible for raised IOP induced glaucoma.
Management after a concomitant cataract surgery.
While, late-onset glaucoma can occur IOP Measurement Following
As DSAEK is a relatively new procedure, due to deranged outflow mechanisms, KPro
larger studies describing the long- loss of angle support, angle closure by
term IOP and IOP treatment-related inflammatory cells and PAS formation, Placement of the PMMA optic and the
outcomes are yet awaited. However, and steroid use. It is noteworthy to 8.5 mm backplate invalidates both
unlike PKP, most patients can be well mention that steroid-induced glaucoma central and peripheral GAT values.
managed medically by increasing their after DMEK is not as common as that While tonopen readings at the limbus
antiglaucoma medications and/or after PKP or DSAEK. This is most may give a rough estimate of IOP, they
by tapering/ switching to less potent probably due to less inflammation, are highly variable. IOP estimates using
steroids. If a GDD is planned, it is short steroid regime and less chances of globe palpation (fingers placed above
important to prevent impingement of graft rejection post-DMEK. the tarsal plate with patient gently
the valve against the thick edge of the looking down) is the most commonly
corneal graft. Using a short tube in AC Management employed method of assessing IOP in
placed tangentially into the angle may these patients.
be more helpful. A pupillary block can be prevented
by reducing the air fill to 50% (only Management
E. Glaucoma Following DMEK 20% to 30% in phakic eyes) at about A meticulous preoperative evaluation
1 hour after surgery. If developed, it is of the angles and the optic disc,
DMEK does not increase the risk of usually temporary, and can be treated either clinically or ultrasonically, is
uncontrolled glaucoma compared by pupillary dilation and laying the mandatory to predict the postoperative
to PKP and DSAEK. The 12-month patient down in a supine position, or
incidence of post-DMEK glaucoma has by the reducing the air bubble via a
10 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
development or progression of References 6. Naveiras M, Dirisamer M, Parker J, et
glaucoma in patients planned for al. Causes of glaucoma after descemet
KPro. The management of this type of 1. Zemba M, Stamate AC. Glaucoma membrane endothelial keratoplasty. Am
glaucoma is usually surgical. A GDD after penetrating keratoplasty. Rom J J Ophthalmol. 2012 May;153(5):958-966.
implant can be placed at the time of Ophthalmol. 2017 Jul-Sep;61(3):159-165. e1.
KPro implantation in eyes with mild
optic nerve head damage and at least 2. Al-Mahmood AM, Al-Swailem SA, Corresponding Author:
3-6 months before KPro implantation Edward DP. Glaucoma and corneal
in individuals with uncontrolled IOP transplant procedures. J Ophthalmol. Prof. (Dr.) Namrata Sharma, MD
or advanced optic nerve damage. The 2012;2012:576394. Cornea & Refractive Surgery Services
incidence of severe infection with GDD Dr. Rajendra Prasad Centre for Ophthalmic
is comparable to that after standard 3. Borderie VM, Loriaut P, Bouheraoua N, Sciences, All India Institute of Medical
trabeculectomy. et al. Incidence of Intraocular Pressure Sciences, New Delhi-110029,India
Elevation and Glaucoma after Lamellar
Conclusion versus Full-Thickness Penetrating
Secondary glaucoma associated with Keratoplasty. Ophthalmology. 2016
keratoplasty is challenging to diagnose Jul;123(7):1428-34.
as well as manage. Most common risk
factor includes presence of pre-existing 4. Huang OS, Mehta JS, Htoon HM, et al.
glaucoma. It is important to assess for Incidence and Risk Factors of Elevated
risk factors preoperatively for best graft Intraocular Pressure Following Deep
related outcomes. Management depends Anterior Lamellar Keratoplasty. Am J
on the type of surgery undertaken and Ophthalmol. 2016 Oct;170:153-160.
severity of the disease.
5. Maier AK, Wolf T, Gundlach E, et al.
Intraocular pressure elevation and post-
DMEK glaucoma following Descemet
membrane endothelial keratoplasty.
Graefes Arch Clin Exp Ophthalmol.
2014 Dec;252(12):1947-54.
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Subspeciality-Glaucoma
Target IOP in Different Glaucomas,
Adult and Pediatric
Vaishali Rakheja, Karthikeyan Mahalingam, Ramanjit Sihota
Glaucoma research facility and services, Dr Rajendra Prasad Centre for Ophthalmic Sciences,
All India Institute of Medical Sciences, New Delhi 110029
Introduction with treatment that is expected biomicroscopic Optic Nerve Head
Glaucoma is a multifactorial disease to prevent further glaucomatous evaluation can help in estimating
characterized by definitive, progressive, damage”[7] the baseline structural damage to
irreversible optic neuropathy. The the nerve.
pathophysiology can be summarized B. American Academy of 2. Intra-Ocular Pressure– Baseline
as perfusion loss manifesting Ophthalmology defines target IOP is defined as the IOP at which
anatomically as accelerated loss of the IOP as “a range of IOP adequate to the optic nerve damage has likely
retinal nerve fibers and corresponding stop progressive pressure-induced occurred. Keeping in mind the
functional visual field defects. It can injury”[8] diurnal variations in IOP it should
be staged as mild, moderate, and severe ideally be assessed by taking three
disease by clinical evaluation of the C. World Glaucoma Association consecutive IOP measurements
optic nerve head and perimetry. Intra- defines it as “an estimate of the at a different time of the day. On a
Ocular Pressure is currently the only mean IOP at which the risk of follow-up IOP should be compared
modifiable risk factor that has been decreased vision-related quality of to the readings taken at the
explored elaboratively to control the life due to glaucoma exceeds the corresponding times if feasible.
progression of this entity. Hence, it risk of the treatment.”[9] 3. Perimetry – the characteristic
is imperative to define and attempt visual field defects in glaucoma
to achieve an IOP range that will Target IOP is hence a guesstimate range which are reproducible on at least
potentially stabilize the progression of of IOP that is expected to at least two consecutive visual fields aid
the disease. in staging of the functional visual
slow the progression of the disease if not loss and form an important factor
It is important to remember that Mean completely halt it. Certain parameters to determine the progression of the
Ocular perfusion pressure=2/3 (mean have to be taken into consideration disease. Hence, reliable baseline
arterial pressure- IOP). This is affected when chalking out the target range of perimetry is an indispensable tool
by cardiovascular factors, IOP, and is IOP and it has to be individualized for in determining target IOP.
another major factor in the pathogenesis every patient. 4. Central Corneal Thickness(CCT)-
of glaucomatous optic neuropathy. Reflective of lamina cribrosa
Essential ocular parameters morphology
The mean IOP in the normal population for determining Target IOP 5. Pseudo-exfoliation.
has been reported to be 14-17 mmHg range
with some racial variations.[1-6] A raised
IOP will induce a neuropathy with 1. A thorough clinical examination
permanent visual field loss. The aim of specifically a careful slit-lamp
therapy in a patient with glaucoma is
to prevent this irreversible visual field
loss so that the patient can continue his
daily pursuits.
Defining the Target IOP- Fig 1. Mild glaucoma with one optic nerve head pole showing a localized loss, moderate
A. European Glaucoma Society glaucoma with both poles showing a thinning, and gross loss of neuroretinal rim all around
in severe glaucoma
guidelines define target IOP as “an
estimate of the mean IOP obtained
12 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Other parameters to be considered However, target IOP is dynamic and
1. Age – Collaborative Initial Glaucoma Treatment Study (CIGTS) and Early evolving and may need to be modified
in the wake of ongoing anatomical and
Manifest Glaucoma Trial (EMGT) that studied the natural course and predictors functional progression if seen despite
of open-angle glaucoma and emphasized that old age is associated with both an the present target being achieved. On
increased risk and aggressive course of the disease.[10,11] the contrary, in cases of aggressive
2. Patient’s life expectancy. therapy with a stable course but
3. Ocular perfusion- Associated cardiovascular co-morbidities also have a bearing leading to deleterious systemic effects,
on the long-term disease progression and should be taken into account when the treatment needs to be changed to
designing a tailored approach. [10] ensure a better quality of life. Hence,
4. Family history of aggressive glaucoma in parents or siblings. [10] there is no single safe level of IOP that
Several staging systems have been proposed to quantify the extent of glaucomatous will apply to all patients at all times and
damage, Hodapp Parish Anderson, Glaucoma Severity Score to name a few. These some patients will continue to progress
take into consideration the baseline structural damage to the optic nerve, the visual owing to the individual risk factors.
field defects, and their proximity to the center of fixation to stage the disease as
mild, moderate, and severe. Various methods can be used to derive
the desirable target IOP.
Fig 2. Pattern deviation plot on HFA or corrected probability plot on Octopus for Mild and
moderate glaucoma, and Total deviation plot for advanced glaucomatous loss. a. An absolute number or a
The stage of the disease is ascertained after a careful clinical and perimetric threshold target range as has
evaluation, the risk factors are recorded and a target IOP is then set accordingly. been described that can be applied
In mild glaucoma, the initial target IOP range could be kept as 15-17 mmHg, for to a large population but tend
moderate glaucoma 12-15 mmHg, and in the severe stage of glaucomatous damage to ignore the heterogeneity and
10-12 mmHg. varied response to therapy in each
individual. The advanced glaucoma
Table: Hodapp Parish Anderson Classification intervention study described that
maintaining a target IOP of <18
HPA Classification MD< -6 dB mmHg at a moderate stage of
PSD < 25% points depressed below 5% level (< 10 glaucoma with MD -10dB showed
Early defect points below 1% level) no progression over 8 years of
Moderate defect Points in central 5°: sensitivity of atleast 15dB trial[12] A study was conducted in
MD< -12 dB India on two-hundred and forty-five
Severe defect PSD < 50% points depressed below 5% level (< 20 eyes of POAG and PACG patients
points below 1% level) over 5 years, with a “target” IOP
Points in central 5°: sensitivity more than 0dB of < 18 mmHg in all eyes, except
Only one hemifield have a point with sensitivity severe glaucoma where the “target”
<15dB within central 5° was 12–14 mmHg. It showed
MD> -12 dB that 12.1% and 15.5% of POAG
PSD > 50% points depressed below 5% level (> 20 and PACG eyes progressed over 5
points below 1% level) years, respectively. [13] Moderate
Atleast 1 point in central 5° has sensitivity 0dB glaucomas commonly progressed,
Both hemifield have a point with sensitivity <15dB 32/31.5% and 26.6/25% in POAG
within central 5° and PACG respectively, implying
that a target IOP of < 18 mmHg
was not low enough in such eyes.
Eyes with severe glaucoma rarely
progressed when the target IOP was
maintained in the lower teens- 10-
12mmHg.[14]
b. Percentage reduction in IOP from
the baseline- the pioneer RCTs in
glaucoma have targeted percentage
reduction in IOP from baseline.
In the Ocular Hypertension
Treatment Study (OHTS)
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 13
Subspeciality-Glaucoma
glaucomatous damage progressed could be set for these patients with possible visual function in the long
even when a target reduction of 20 such risk factors and systemic co- term keeping in mind the longer life
% from the baseline IOP or an IOP morbidities.[17] expectancy. Owing to the elasticity
<24mmHg was maintained. An yy For a patient with early POAG/PACG, and pliability of the ocular tissues in
Indian study[13] showed perimetric an IOP set in the mid-teens, 15-17 children, a higher baseline IOP will
progression in 21.3% of POAG mmHg, should be initially aimed lead to stretching of ocular coats and
and PACG eyes with moderate for and modified after a 6 monthly axial lengthening. When compared to
glaucomatous damage over 5 review. the adult counterparts the optic disc
years when the target IOP was <18 cupping in childhood differs in being
mmHg. For a patient with moderate yy In POAG and PACG eyes with reversible if adequate IOP reduction is
glaucomatous optic neuropathy, moderate glaucomatous damage, achieved early on.
it appears that lower IOPs, with an a target IOP of 12-15 mmHg may
upper limit of 15 mmHg, could be stabilize the visual functions [13] Hence, the target IOP in this age group is
required to stabilize VFs. The AGIS ideally expected to be associated with an
showed significant worsening yy Whereas in advanced POAG/PACG increased frequency of reversal/stability
continues even when the IOP an aggressive approach with target of the optic neuropathy and ocular
is brought down by 40%.[12] An IOP range in lower teens shows enlargement. Recording the visual
Indian study performed in subjects reduces progression 5%.[13] acuity and perimetry is not feasible
with advanced glaucomatous in very young children therefore the
damage showed that over 5 years, yy A 30% reduction from baseline has appearance of the optic nerve head-
progression occurred only in proven beneficial in patients with cup: disc ratio, neuro-retinal rim, axial
2.3% of POAG and PACG patients Normotensive glaucoma.[18] length, and refractive error can be used
when IOP was maintained at 12-14 as surrogate biomarkers to monitor the
mmHg[13] Table: Target IOP in primary adult response to the therapy and estimate
c. Formula-based methods though glaucomas – POAG & PACG the residual visual function. There
cumbersome to apply but offer exists a significant correlation of IOP
an individualized approach to Clinical Entity Target IOP with the cup: disc ratio, and after
each patient. Formulas tend to OCULAR <18mmHg surgical reduction in IOP, a reversal of
incorporate baseline and risk HYPERTENSION/ cup: disc ratios observed once adequate
factors into determining “target” PAC with OHT 15-17mmHg IOP control is achieved over a long time.
IOP. Jampel first calculated target POAG/PACG- Early 12-15mmHg
IOP by taking into account several damage 10-12mmHg Table: Normal IOP in infants
attributes of the patient – initial POAG/ PACG- 30% reduction
pretreatment IOP, Z score (an Moderate damage from baseline AGE GROUP Normal IOP[19]
indicator of disease severity), and Y POAG/PACG- Neonate- 6 Around 8 – 10
factor (burden of therapy).[40] Advanced damage months mmHg
Target IOP = (Initial IOP × [1 – initial NORMAL TENSION 6 months to 10 -12mmHg
pressure/100] − Z + Y ± 1 mmHg) GLAUCOMA 10-12 years
Modified equations increased the range
of Z score, 0–7.[15,16] Target IOP in childhood Children diagnosed with congenital
glaucomas- glaucoma having glaucomatous optic
Clinical Guidelines for setting Childhood glaucoma is a heterogeneous neuropathy should probably have their
the target IOP- group of disorders with an aggressive IOPs reduced to at least such levels, to
POAG eyes and PACG eyes after iridotmy clinical course and is a challenging optimize the function of their already
respond similarly. entity to manage. Contrary to popular damaged optic nerves.
belief held a few decades back, that
yy In ocular hypertension or PAC with congenital glaucoma had a grave A study conducted by Ely et al showed a
ocular hypertension, the decision to prognosis, outcomes have now 58% reversal of cup-disc ratio at a mean
start medical therapy rests on the significantly improved by achieving IOP of 13.3 ± 2.1.12[20] Zhang et al found
presence of high-risk factors such as better IOP control. no cup disc ratio reversal overall with a
– a family history, high baseline C: D mean post-op IOP of 19.22 ±8.67 mmHg,
ratio, high baseline IOP > 26mmHg, The most suitable target IOP in such however, when they looked at eyes with
low central corneal thickness (CCT), children remains questionable, a lower mean IOP of 14.31 ±3.94mmHg,
and older age. A target of <18 mmHg although, logically it should at least the mean cup: disc ratio of 63% eyes
approach normal IOP in children, was significantly reduced from 0.74
and be set such as to provide the best ±0.18 pre-operatively to 0.56 ±0.16
14 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
post-operatively.13[21] Alsheikheh et al Table- common causes of secondary glaucoma
showed a decreased cup-disc ratio in
31.2% of congenital glaucoma eyes, no Adults Childhood Childhood Childhood
change in 40%, and an increase in 29.5% Lens induced glaucoma- glaucoma- glaucoma-
at an IOP of < 21 mmHg.14[22] Wu et al glaucoma Non-Acquired with Non-Acquired Acquired
with a similarly high Target of IOP < 22 Neovascular ocular anomalies with systemic
mmHg after trabeculotomy, recorded a glaucoma Aniridia anomalies Post-surgical
reversal of cup-disc ratio in 61.1% of Pseudophakic Axenfeld Reiger’s Chromosomal glaucoma
18 eyes from 0.74 ± 0.20 to only 0.60 glaucoma spectrum disorders (Trisomy Retinopathy of
± 0.21.15 [reference] Studies described Uveitic Congenital ectropion 21) prematurity
that children with post-operative glaucoma uvea Connective tissue Steroid induced
IOP <15mmHg or lower, have shown Traumatic Iris Hypoplasia disorders (Marfan’s Trauma
smaller cup-disc ratios in primary glaucoma Microphthalmia syndrome ) Tumors
congenital glaucoma eyes over time. Steroid Oculodermal Metabolic disorders Uveitis
Quigley proposed that due to elasticity induced melanocytosis (Homocystenuria)
of the ocular tissues in the young glaucoma Peter’s anomaly Phakomatosis
lamina cribrosa could be expected PFV (Sturge Weber
to return towards normality with a Posterior Syndrome,
significant decrease in IOP, however, polymorphous Neurofibromatosis)
the eyes with significant glaucomatous corneal dystrophy Congenital Rubella
damage exhibited smaller reversal.[23,24] Ectopia lentis syndrome
Preexisting glaucomatous optic Again, the following ocular parameters many other factors such as diurnal &
neuropathy at the presentation need to be assessed when customizing intervisit IOP fluctuations, systemic
in primary congenital glaucoma target IOP for a patient with secondary microvasculopathy and steroid
eyes could be exaggerated by glaucoma. response that also play a role in disease
continuing mechanical damage due progression. Modification of target IOP
to inappropriate IOP levels set at 1. Baseline IOP of are required over a patient’s lifetime
21mmHg, 18 mmHg, etc, that have 2. ONH changes at detection with periodic fundus photography,
been thought appropriate in adults. ONH imaging and perimetry.
Glaucomatous optic neuropathy and glaucoma
impaired visual function after surgery 3. Perimetry, if possible Conclusion
in primary congenital glaucoma also IOP is the sole modifiable risk factor,
correlates with fall in mean review Initially, the aim should be to lower and its adequate control can prevent
IOP. IOP to that normal for age, adults 14- irreversible blindness. In adults, the
17mmHg and children 10-12 mmHg target IOP is largely based on baseline
Secondary glaucomas and review over time. glaucomatous optic neuropathy and
risk factors for progression. These
Secondary glaucomatous neuropathy It has been seen that once the cannot be applied to childhood
is primarily the result of raised IOP, underlying cause such as uveitis, glaucomas with similar predictability,
as the other risk factors of vascular trauma etc has been controlled and and lower IOP levels are required.
compromise and familial predisposition resolves, medications can be gradually
are not present. tapered to maintain such normal IOPs References
for age.
It is therefore imperative to know 1. Ramakrishnan R, Nirmalan PK,
the common causes of secondary Periodic assessment/ Krishnadas R, Thulasiraj RD, Tielsch
glaucoma at different ages in India, and modification and lifelong JM, Katz J, et al. Glaucoma in a rural
have a high suspicion, looking for an review population of Southern India: The
early rise in IOP. Unfortunately, most Aravind comprehensive eye survey.
secondary glaucomas are diagnosed Determining the target IOP is a crucial Ophthalmology 2003;110:1484-90.
late as ophthalmologists concentrate step in the management of glaucoma,
on treating the primary pathology. A and it is important to remember that 2. Nangia V, Jonas JB, Matin A, Bhojwani
comprehensive examination, especially achieving the set target IOP does K, Sinha A, Kulkarni M, et al. Prevalence
tonometry and anterior chamber not always guarantee the cessation and associated factors of glaucoma in
evaluation would alert one to possible of disease progression. There are rural central India. The central India
glaucoma.
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 15
Subspeciality-Glaucoma
eye and medical study. PLoS One Ophthalmology. 1999 Apr;106(4):653- primary congenital glaucoma in China.
2013;8:e76434. 62. doi: 10.1016/s0161-6420(99)90147-1. Clinics 2009;64:543–51
PMID: 10201583. 21. Alsheikheh A, Klink J, Klink T, et
3. Vijaya L, Rashima A, Panday M, al. Long-Term results of surgery in
Choudhari NS, Ramesh SV, Lokapavani 12. The Advanced Glaucoma Intervention childhood glaucoma. Graefes Arch Clin
V, et al. Predictors for the incidence of Study (AGIS): 7. The relationship Exp Ophthalmol 2007;245:195–203.
primary open-angle glaucoma in a south between control of intraocular pressure 22. Meirelles SHS, Mathias CR, Bloise RR,
Indian population: The Chennai eye and visual field deterioration. The Stohler NSF, Liporaci SD, Frota AC,
disease incidence study. Ophthalmology AGIS investigators. Am J Ophthalmol Simões CC (2008) Evaluation of the
2014;121:1370-6. 2000;130:429-40. factors associated with the reversal of
the disc cupping after surgical treatment
4. Vijaya L, George R, Baskaran M, Arvind 13. Rao A, Sihota R, Srinivasan G, Gupta V, of childhood glaucoma. J Glaucoma
H, Raju P, Ramesh SV, et al. Prevalence Gupta A, Sharma A, et al. Prospective 17:470–473
of primary open-angle glaucoma in an evaluation of optic nerve head by 23. Harry Quigley, Karun Arora, Sana
urban South Indian population and confocal scanning laser ophthalmoscopy Idrees, Francisco Solano, Sahar Bedrood,
comparison with a rural population. after intraocular pressure control in Christopher Lee, Joan Jefferys, Thao D.
The Chennai glaucoma study. adult glaucoma. Semin Ophthalmol Nguyen; Biomechanical Responses of
Ophthalmology 2008;115:648-540. 2013;28:13-8. Lamina Cribrosa to Intraocular Pressure
Change Assessed by Optical Coherence
5. Fukuoka S, Aihara M, Iwase A, 14. Sihota R, Midha N, Selvan H, Sidhu T, Tomography in Glaucoma Eyes. Invest.
Araie M. Intraocular pressure in an Swamy DR, Sharma A, et al. Prognosis Ophthalmol. Vis. Sci. 2017;58(5):2566-
ophthalmologically normal Japanese of different glaucomas seen at a tertiary 2577
population. Acta Ophthalmol center: A 10-year overview. Indian J 24. Mandal AK, Chakrabarti D (2011)
2008;86:434-9. Ophthalmol 2017;65:128-32. Update on congenital glaucoma. Indian
J Ophthalmol 59(Suppl):S148–S157
6. Tomoyose E, Higa A, Sakai H, 15. Aquino MV. Suggested formula for 25. MacKinnon JR, Giubilato A, Elder JE,
Sawaguchi S, Iwase A, Tomidokoro A, setting target intraocular pressure. et al. Primary infantile glaucoma in
et al. Intraocular pressure and related Asian J Ophthalmol 2004;6:2-6. an Australian population. Clin Exp
systemic and ocular biometric factors Ophthalmol 2004;32:14–18.
in a population-based study in Japan: 16. Zeyen T. Target pressures in glaucoma.
The Kumejima study. Am J Ophthalmol Bull Soc Belge Ophtalmol 1999;274:61-5 Corresponding Author:
2010;150:279-86.
17. Artes PH, Chauhan BC, Keltner JL, Dr. Ramanjit Sihota
7. European Glaucoma Society Cello KE, Johnson CA, Anderson DR, Glaucoma research facility and services,
Terminology and Guidelines for et al. Longitudinal and cross-sectional Dr Rajendra Prasad Centre for Ophthalmic
analyses of visual field progression in Sciences, All India Institute of Medical Sciences,
Glaucoma. 3rd ed. Savona, Italy: participants of the ocular hypertension New Delhi 110029
DOGMA; 2008. treatment study. Arch Ophthalmol
2010;128:1528-32
8. American Academy of Ophthalmology.
Primary Open-Angle Glaucoma. 18. Anderson DR; Normal Tension
Preferred Practice Pattern. San Glaucoma Study. Collaborative normal
Francisco, CA: American Academy of tension glaucoma study. Curr Opin
Ophthalmology; 2010. Ophthalmol. 2003 Apr;14(2):86-90. doi:
10.1097/00055735-200304000-00006.
9. World Glaucoma Association Consensus PMID: 12698048.
Statement: Intraocular Pressure. The
Netherlands: Kluger; 2007. 19. Bresson-Dumont H. La mesure de la
pression intra-oculaire chez l’enfant
10. Leske MC, Heijl A, Hussein M, et al. [Intraocular pressure measurement
Factors for Glaucoma Progression in children]. J Fr Ophtalmol. 2009
and the Effect of Treatment: The Mar;32(3):176-81. French. doi: 10.1016/j.
Early Manifest Glaucoma Trial. Arch jfo.2009.03.008. PMID: 19515328.
Ophthalmol. 2003;121(1):48–56.
doi:10.1001/archopht.121.1.48 20. Ely AL, El-Dairi MA, Freedman SF (2014)
Cupping reversal in pediatric glaucoma–
11. Musch DC, Lichter PR, Guire KE, evaluation of the retinal nerve fiber
Standardi CL. The Collaborative layer and visual field. Am J Ophthalmol
Initial Glaucoma Treatment Study: 158:905–915Zhang X, Du S, Fan Q, et
study design, methods, and baseline al. Long-Term surgical outcomes of
characteristics of enrolled patients.
16 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Role of Meditation an Adjunctive
Therapy in Glaucoma
Ragini Sonker, Karthikeyan Mahalingam, Tanuj Dada
Dr Rajendra Prasad Centre for Ophthalmic Sciences,
All India Institute of Medical Sciences, New Delhi 110029
Introduction in oxidative stress causing damage Meditation
Glaucoma is a ‘neurodegenerative to both retinal ganglion cells and
disease’ causing chronic progressive trabecular meshwork. Chronic stress Meditation was described in the second
irreversible optic neuropathy due to the can lead to an increase in endogenous century BC in the ‘Indian Saint Patanjali’
loss of retinal ganglion cells. The major corticosteroids.2 Glucocorticoids (raised as the final stage in the eight stages of
mechanisms causing optic neuropathy free plasma cortisol) levels alter the ‘YOGA’ to achieve holistic health and a
include: raised intraocular pressure extracellular matrix of trabecular higher state of awareness. Meditation is
causing barotrauma to the optic nerve meshwork causing an imbalance in a practice of self - regulation that focus
and its axons, ischemia due to vascular glycosaminoglycans level leading to on training attention and awareness to
dysregulation/autonomic dysfunction abnormal phagocytosis and cytoskeletal bring mental processes under greater
and decrease in brain-derived network with upregulation of MYOC/ voluntary control. It consists mainly
neurotrophic factors such as BDNF.1 TIGR gene predisposing to glaucoma. of two styles ‘Focused attention’ and
We are aware that chronic stress can lead Pro-inflammatory mediators such as ‘Open monitoring’. Focused attention
to systemic hypertension (raised Blood interleukin-6, TNF– alfa, and C-reactive describes one’s attention concentrating
Pressure) but have not given thought to protein (CRP) are raised in the stressful on a particular object or sound (mantras)
the fact that stress can also lead to ocular condition causing an inflammatory and or breathing pattern. Open monitoring
hypertension (raised IOP) . These effects oxidative loss in glial cells resulting in does not require fixing attention on a
are primarily mediated by endogenous ganglion cell damage. specific object but involves awareness of
cortisol and catecholamines which are the mental content without reacting to
both raised in glaucoma patients. While Glaucoma is the leading cause of them. The benefit from YOGA does not
we focus on lowering IOP with medical/ irreversible blindness, so it can affect involve physical posture or exercises, it
surgical therapy for the eye pressure, it the quality of life of both patient includes meditation focused on breath
is also important to focus on the patient and family by putting them under with slow and deep breathing which
as a whole and adopt lifestyle changes psychological stress. This stress can leads to stress reduction with reduction
to improve the quality of life of the further lead to worsening of glaucoma. of sympathetic outflow and enhanced
patients. Younger patients have more propensity parasympathetic flow with a decrease
for anxiety and depression is more in stress. This is called ‘The relaxation
Effect of stress in Glaucoma common in the geriatric population. response’ – a term coined by Herbert
“Brain–eye–vascular triad” proposed by The National Health and Aging Benson.3
Flammer and Sabel has been observed in Trends study showed a bidirectional
glaucoma where vascular dysregulation relationship between mental health Meditation in Glaucoma
was noted in the microvasculature of the disorders and visual impairment.
central nervous system and optic nerve Cognitive impairment reduces Meditation has different mechanisms
following stress and psychosomatic compliance to treatment schedule to work in glaucoma as an adjuvant
changes. The stressful situation leads and also reduce the ability to follow such as: reducing intraocular pressure,
to abnormal ocular blood flow, increased physical orders which affects treatment enhancing cerebral blood flow,
resistance in retro-ocular blood flow, outcomes. Quality of life is hampered reversing autonomic dysfunction,
increased optic disc hemorrhages, and in current treatment regimens due to decreasing oxidative stress and
abnormal retinal vessels. Mitochondrial long term side effects of medications preventing mitochondrial dysfunction,
dysfunction leads to an overall increase and vision-threatening complications decreasing inflammation, reducing
following surgical procedures. glutamate excitotoxicity, upregulating
BDNF, preventing neurodegeneration,
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 17
Subspeciality-Glaucoma
improving quality of life, modulating Centre, AIIMS, new Delhi to evaluate Comprehensive Management of
wound healing and modifying other the effect of mindfulness meditation on Glaucoma Patients. J Glaucoma. 2020
associated systemic diseases.3–5 trabecular meshwork gene expression Feb;29(2):133–40.
in glaucoma patients,6 it was found
Meditation causes an increased level of that meditation alters gene expression, 4. Dada T, Mittal D, Mohanty K, Faiq MA,
melatonin by direct stimulation of the positively modulating cellular Bhat MA, Yadav RK, et al. Mindfulness
pineal gland has been found effective mechanisms involved in glaucoma Meditation Reduces Intraocular
in reducing intraocular pressure in pathogenesis thereby indicating Pressure, Lowers Stress Biomarkers
glaucoma.3 Meditation increases nitric its direct impact on ocular tissues. and Modulates Gene Expression in
oxide level which helps to control Gagrani et al reported that meditation Glaucoma: A Randomized Controlled
intraocular pressure by increasing upregulates BDNF, enhances brain Trial. J Glaucoma. 2018;27(12):1061–7.
conventional aqueous outflow. There is oxygenation, and also improves the
also an upregulation of gene expression quality of life in patients with primary 5. Gagrani M, Faiq MA, Sidhu T, Dada R,
of endothelial and neuronal nitric open-angle glaucoma.5
oxide synthetase in the trabecular Yadav RK, Sihota R, et al. Meditation
meshwork (NOS1 and NOS3) following Glaucoma is a challenging disease to enhances brain oxygenation,
meditation.3 treat and despite recent advances in
treatment modalities and adequate upregulates BDNF and improves
control of IOP, patients often have quality of life in patients with primary
a poor quality of life. Incorporating open angle glaucoma: A randomized
the practice of meditation focused controlled trial. Restor Neurol Neurosci.
on the breath can significantly alter
the course of the disease not only by 2018;36(6):741–53.
lowering IOP but also be reversing
Psychological stress triggers vascular dysregulation and improving 6. Dada T, Bhai N, Midha N, Shakrawal J,
(CHR) corticotrophin-releasing the overall quality of life of the patients. Kumar M, Chaurasia P, et al. Effect Of
hormone which releases (ACTH) Current evidence strongly supports the Mindfulness Meditation On Intraocular
adrenocorticotropic hormone which use of meditation as adjunctive therapy Pressure and Trabecular Meshwork
releases cortisol ending up raised for glaucoma patients. Gene Expression: A Randomised
intraocular pressure while meditation Controlled Trial. Am J Ophthalmol.
counteracts this response and lowers 2020 Oct 22;0(0).
cortisol and can thereby help in
lowering intraocular pressure.
Patients with normal pressure References Corresponding Author:
glaucoma have autonomic dysfunction
with a predominance of activity of 1. Dada T, Gagrani M. Mindfulness Dr. Tanuj Dada, MD
the sympathetic nervous system flow Professor of Ophthalmology
which leads to arterial vasoconstriction, Meditation Can Benefit Glaucoma Dr Rajendra Prasad Centre for Ophthalmic
endothelial dysfunction, increase Sciences, All India Institute of Medical Sciences
oxygen demand with a reduced Patients. J Curr Glaucoma Pract. New Delhi 110029, India
threshold to ischemic damage.
Meditation helps to decrease the activity 2019;13(1):1-2. doi:10.5005/jp-
of the sympathetic nervous system
and upregulates the parasympathetic journals-10078-1239.
nervous system which helps to augmant
the blood flow to the optic nerve.3 2. Lee DY, Kim E, Choi MH. Technical
and clinical aspects of cortisol as a
biochemical marker of chronic stress.
BMB Rep. 2015 Apr;48(4):209–16.
In a recent trial conducted at Dr. R. P. 3. Dada T, Ramesh P, Shakrawal
J. Meditation: A Polypill for
18 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Minimally Invasive Glaucoma
surgeries ( MIGS) : A Revolution in
Glaucoma Surgery
Suneeta Dubey1, Tanima Bansal2
1. Head of Glaucoma Services
1, 2. Dr. Shroff’s Charity Eye Hospital , Delhi
Glaucoma is a chronic eye disease Definition of MIGS iv) High safety profile: These
and one of the leading causes of MIGS as explained by Saheb H surgical procedures carries a very
blindness worldwide.1 The treatment and Ahmed I3 are group of surgical less risk of vision threatening
of glaucoma focuses on preventing interventions that share the following complications such as hypotony,
and slowing the development and characteristics: choroidal effusions, choroidal
progression of optic nerve damage with haemorrhages.
intraocular pressure (IOP) lowering i) Ab interno approach: These surgical
measures such as topical hypotensive procedures are performed from a v) Rapid patient recovery: Allows fast
agents, laser trabeculoplasty and clear corneal incision with direct recovery and if required can be
filtration surgery. Surgery is typically visualisation of internal anatomical combined with cataract surgery.
performed when non-invasive options structures that are the target site.
(Maximal medical therapy/ Laser With this new revolution in glaucoma
trabeculoplasty) have been exhausted ii) Minimal disruption of normal surgery, MIGS represent an evolving
and are incapable of reaching target anatomy: Micro incisional, field, in which the efficacy and
IOP levels. Trabeculectomy with conjunctiva-sparing procedures complications of each procedure should
antimetabolites and glaucoma drainage with minimal alteration in the be considered independently. MIGS
devices have been the gold standard normal anatomy. offer IOP lowering by targeting various
procedures and very successful in aspects of normal aqueous dynamics
reducing IOP but can be associated iii) Good efficacy: IOP decrease of and can be classified on the same basis
with plethora of complications which 20% or reduction of at least one as shown in Fig 1.
can be vision threatening.2 This has medication.
led and necessitated the need for the
development of alternate modalities in Fig 1: Classification of MIGS on the basis of the site of action
glaucoma treatment paradigm with a
better safety outcomes and lower risk
profiles. More recently, less invasive
glaucoma procedures, collectively
termed micro invasive glaucoma
surgery (MIGS) have gained popularity,
with new devices entering the market
on a regular basis.
MIGS is intended to bridge the treatment
gap that exists between medical therapy
and more aggressive traditional surgical
options thus providing good balance
between safety and efficacy.
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 19
Subspeciality-Glaucoma
MIGS enhancing aqueous canal has three retention arches to Indication of iStent use is along
outflow across trabecular safeguard its secure placement. The with cataract surgery in adult
meshwork and through iStent is preloaded into a single-use patients with mild to moderate
Schlemm’s Canal sterile injector. open angle glaucoma on ocular
Physiologically, the trabecular or 2) iStent inject (Glaukos, Laguna hypotensive agents.4
conventional pathway accounts for Hills, CA): It is second generation
the major portion of aqueous humour model of trabecular meshwork Contraindications for its use are
outflow. The site of resistance along bypass stent approved by FDA primary angle closure glaucoma,
this pathway can be at three levels: in 2018.5 Like its first generation, secondary angle closure glaucoma
at juxtacanalicular trabecular level; iStent inject (Figure 3) is also including neovascular glaucoma
collapse of Schlemm’s canal; closing heparin-coated, non-ferromagnetic and conditions associated with
of collector channels. MIGS under this titanium device. iStent inject unlike elevated episcleral venous pressure.4
category targets resistance at any of the its first generation comes with two
above three level and can further be preloaded stents, each of which Complications associated
subclassified into: are placed 2-3 clock hours apart in are Transient hyphema, stent
the nasal angle. Each stent is bullet obstructions, malpositioning.6
I. Trabecular meshwork bypass shaped, 360 microns in height, 230
II. Schlemm’s canal dilatation microns in diameter with a central 3) High-frequency deep sclerotomy
III. Trabeculotomy lumen of 80micron in diameter. (HFDS). Uses a high-frequency
Stent is divided into three parts- diathermic probe to create six small
I. Trabecular meshwork bypass head, thorax and a terminal flange. pockets that penetrate through
The head lies in in Schlemm’s canal the trabecular meshwork and
These devices overcome the resistance and has four outlet each 50 micron Schlemm’s canal, thus creating a
at trabecular level by creating a direct in diameter, the thorax straddles direct communication between
communication between anterior the trabecular meshwork and anterior chamber and Schlemm’s
chamber and Schlemm’s canal. the flange resides in the anterior canal.7 HFDS is done with Oertli
chamber. abee glaucoma probe (Figure
1) iStent (Glaukos, Laguna Hills, 4) which is connected to Orteli
CA) is a L shaped heparin-coated, iStent and iStent inject: How surgical platform.7 A four-mirror
non-ferromagnetic implant made they differ? gonioscopy lens is placed on the
up of titanium (magnetic resonance cornea to view the iridocorneal
imaging-safe up to 3 Tesla).4 yy iStent inject is smaller, with its angle which is the target site
largest dimension measuring 360 for HDFS. It can be performed
It was approved by FDA in 2012. um. along with cataract surgery or
Two models of iStent are available: a standalone procedure (high
GTS100R and GTS100L (“R” and yy iStent utilizes one stent whereas viscoscity viscoelastic is used).
“L” is indicative of right- and left- iStent inject utilizes two stents,
pointed tips, respectively). The thus significantly increase the
iStent (Figure 2) is 0.3mm in height facility of outflow, they leading to
and 1mm in length with a snorkel increased efficacy
that has height of 0.25mm and
a central lumen of 120 microns
which projects into the anterior
chamber. The body of the device
which is implanted into Schlemm’s
Figure 2: iStent Figure3: iStent inject Figure 4: Oertli abee glaucoma probe
II. Schlemm’s canal dilation
Implant works by lowering intraocular
pressure through two mechanisms:
trabecular meshwork bypass stent
and support for Schlemm’s canal to
maintain patency. Schlemm’s canal
20 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
dilation helps as the raised IOP causes of entry. Then it is slowly pulled of viscoelastic in Schlemm’s canal.
the canal to collapse, leading to changes back while injecting viscoelastic to The common complications
in the trabecular meshwork and dilate the canal 2-3 times its normal associated is hyphaema.
schlemm’s canal. size. Also, no permanent device
1) Hydrus Microstent (Ivantis, Inc., and implant is left in the eye. It can Figure 7: Visco360
be done as standalone procedure
Irvine, CA, USA): The microstent or can be combined with cataract III. Trabeculotomy
is 8mm in length and 290 microns surgery.
in diameter with three windows These procedures reduce IOP by
and an inlet, its curved shape helps eliminating the site of resistance
it to match the shape of schlemm’s of aqueous outflow by cleavage of
canal. It is made of nitinol which trabecular meshwork (TM) and
is flexible and biocompatible. The inner walls of Schlemm’s canal
Hydrus microstent (Figure 5) spans with specialized device under direct
3 clock hours of the schlemm’s observation of anterior chamber angle
canal and dilates the canal by 4 to 5 structure, thus creating a direct pathway
times its normal size. It is preloaded to Schlemm’s canal for 90 to 120 degree
into a hand-held delivery system. or more. No implant is required in these
procedures. Disadvantages in these
Figure 6: Abinterno canaloplasty procedures is risk of cleft closure and
IOP reduction is limited by episcleral
Indications of Abinterno venous pressure and Schlemm’s canal
canaloplasty: primary open angle resistance.
glaucoma, pseudoexfoliative
glaucoma, and pigmentary 1) Abinterno trabeculotomy(AIT)
glaucoma. It can also be performed with Trabectome: Trabectome
in patients with previous failed (NeoMedix Corporation, Tustin,
trabeculectomy in which CA) uses a 550KHz bipolar
Figure 5: Hydrus microstent Schlemm’s canal is undamaged. electrocautery to lowers IOP by
plasma mediated ablation of
Indication of Hydrus microstent Patients with angle-closure portion of the trabecular meshwork
use is mild to moderate primary glaucoma, narrow-angle glaucoma and inner wall of Schlemm canal
open angle glaucoma (POAG) in (not undergoing concurrent lens thus exposing collector channels
adult patients.8 extraction), neovascular glaucoma, and improving aqueous outflow.
posttraumatic glaucoma, eyes Unlike cautery, plasma has a highly
Contraindications are-angle with damage to Schlemm’s canal confined heat dissipation cone
closure glaucoma, secondary due to previous ocular surgery or with minimal thermal transfer
glaucoma (traumatic, malignant, extensive laser trabeculoplasty with to the adjoining structures. The
neovascular, uveitic), glaucoma peripheral anterior synechiae will trabectome instrument combines
associated with congenital angle not benefit from this procedure. irrigation, aspiration and ablation
anomalies.8 capabilities within a disposable
Complications- Transient handpiece which is controlled by
Complications are peripheral hyphema, descemet’s detachment, a foot pedal. Ablation is applied for
anterior synechiae, elevated IOP, IOP spikes, hypotony10 60°-120° of trabecular meshwork to
hyphema, malpositioning.6 allow for re-establishment of the
drainage pathway.
2) Abinterno canaloplasty: It is done 3) Visco360 (Slight Sciences,
using the microcatheter system Menlo Park, California): It is an The procedure can be done as
iTrack (Ellex iScience, Fremont, CA). abinterno approach for controlled standalone or combined procedure.
iTrack consists of a microcatheter viscodilation of Schlemm’s canal.
of 250 microns with a fibre optic It uses a single-handed device with
light that allows visualization of a control wheel that advances a
the catheter while in Schlemm’s semi-rigid, polymer microcatheter
canal.9 A nasal goniotomy is with a atraumatic tip while reverse
performed following which the actuation of the wheel retracts
catheter is inserted and advanced the microcatheter and activates
360 degrees into Schlemm’s canal the internal infusion pump that
and circumnavigated to its point deposits a predetermined amount
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 21
Subspeciality-Glaucoma
It can be done as a standalone grasped with help of microsurgical
procedure or in combination forceps and pulled to the centre of
with phacoemulsification (phaco) the anterior chamber, thus shearing
cataract surgery. the entire TM and creating a 360°
trabeculotomy. It can be combined
with cataract surgery13
Indications of use of GATT
are POAG, primary congenital
glaucoma, juvenile open angle
Figure 8: Trabectome glaucoma, patients with previous
Indications of AIT with glaucoma surgery, secondary
glaucoma- pseudoexfoliation
trabectome are adults open angle glaucoma, steroid induced
glaucoma, juvenile open angle
glaucoma, infantile glaucoma, glaucoma. Suture GATT is a cost
Figure 9: Kahook Dual Blade effective procedure.
secondary glaucoma (pigmentary,
pseudoexfoliation, uveitic11 Figure 10: Tip of Kahook Dual Blade Relative contraindication
Indication for its use is treatment includes previous corneal
glaucoma) of open angle glaucoma and ocular transplant surgery.13
hypertension.
Contraindication are narrow Dorairaj and Tam12 reported Complications associated is
angle glaucoma, angles with meaningful IOP and no of transient hyphaema.13
plateau iris configuration, medication reduction in angle
neovascular glaucoma, glaucoma closure glaucoma patients also. 4) Excimer laser trabeculotomy
associated with raised episcleral Contraindicated in patients with (ELT): 308 nm xenon chloride
venous pressure. active angle neovascularisation, excimer laser wavelength is used to
raised episcleral venous pressure, remove the trabecular meshwork
Complications associated with angle dysgenesis. by photoablation without inducing
this procedure are intraoperative thermal damage, thus minimizing
blood reflux, postoperative 3) Gonioscopy Assisted Transluminal healing response and scar
hyphaema, goniosynechiae Trabeculotomy (GATT) is a formation.
formation. minimally invasive ab interno
method for 360° circumferential Enhancing aqueous outflow
2) Kahook Dual Blade Goniotomy trabeculotomy.13Under gonioscopic through uveoscleral
(New World Medical, Rancho guidance goniotomy is done in outflow by assessing the
Cucamonga, CA): Is a specialized the nasal trabecular meshwork. suprachoroidal space
dual blade goniotomy device, With the help of microsurgical
for excision of the trabecular forceps, iTrack microcatheter The MIGS in this group targets the
meshwork by ab interno approach. (Ellex iScience, Fremont, CA) unconventional aqueous outflow the
It was introduced in the United with a 250 microns diameter and uveoscleral pathway.
States in 2015. The blade is single an illuminated distal tip tracking
use disposable blade and has a its location as it is advanced in to 1) CyPass Micro-Stent (Alcon,
sharp tip to pierce and allow for Schlemm’s canal. Once the distal Fort Worth, Texas): This was a
the smooth entry in the trabecular tip has circled the entire canal, it is supraciliary device that worked by
meshwork and schlemm’s canal, creating a controlled cyclodialysis
the heel allows the device to fit cleft to allow outflow of aqueous
smoothly in SC and allows smooth humour to the suprachoroidal
movement of blade inside the canal. space. However, CyPass was
The ramp of the blade stretches the withdrawn from market in August
trabecular meshwork and dual 2018 after it was found that there
parallel blades creates a paired was concerning rise in endothelial
parallel incision in the trabecular cell loss (ECL) among patients who
meshwork. This design allows received the CyPass microstent
for complete excision of a strip during cataract surgery 5 years
of the trabecular meshwork and ago, compared with patients who
thus minimising the potential for underwent cataract surgery alone.14
scarring from residual TM leaflets.
22 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Figure 11: CyPass Micro-Stent injector is inserted into the anterior tissue. The instrumentation
2) iStent Supra (model G3) chamber and its tip is used to pierce consists of an endoscopic probe
through TM and the sclera into the which includes a diode laser
(Glaukos): The stent is a 4-mm subconjunctival space. The slider (810nm), a xenon light source, a
long curved stent with a lumen of of the injector is advanced to deploy helium-neon aiming beam, and
0.165 mm made of a biocompatible the stent into place and create an fibre optic imaging.17 The video
polymer with a titanium sleeve. outflow from the anterior chamber monitor is provided for endoscopic
iStent supra comes preloaded to the subconjunctival space. After viewing for the surgeon and a foot
in injector. It is inserted using implantation, the gelatin of the pedal allows for control of the laser.
ab interno approach under stent hydrates causing expansion The probes of ECP comes in straight
gonioscopic visualization into of the device to ensure improved or curve 19, 20, 23 gauze size that
suprachoroidal space. It can be stability. The inner diameter of the can be inserted into the anterior
performed as standalone procedure implant is 45 microns in diameter chamber through a clear corneal
or can be combined with cataract and the outer diameter is 150 incision. Laser setting start at 0.2-
surgery for mild to moderate microns. 0.25 Watts, which is adjusted by the
glaucoma. surgeon to achieve both blanching
Figure 13 : Xen Gel stent and contraction of the ciliary
processes. 200-360 degrees of the
angle are treated.17
Indications - Patients with Figure 14: Endocyclophotocoagulation
uncontrolled glaucoma,
primary open angle glaucoma, Indications of ECP: ECP is an
pseudoexfoliative and pigmentary efficacious tool for the treatment
glaucoma with open angles that of refractory glaucoma.18 It
are unresponsive to maximum has been utilized in various
tolerated medical therapy.16 types of glaucoma including
primary open-angle, angle-
Figure 12: iStent supra Contraindications - angle closure closure, aphakic/pseudophakic,
glaucoma, neovascular glaucoma, uveitic, pigmentary, neovascular,
Shunting aqueous outflow eyes with conjunctival scarring at traumatic, paediatric.18 However
into the subconjunctival the site of placement, eyes with patient selection should be done
space active inflammation, silicone filled meticulously considering the risk
MIGS reduces IOP by shunting the eyes, eyes with impaired episcleral of complications associated with it.
aqueous from anterior chamber to venous drainage pressure.16
subconjunctival space and forming a Complications of ECP: May be as-
bleb. Complications - No serious sociated with vision, haemorrhage,
complications are reported in the increased inflammation, excessive
1) XEN Gel Stent / AqueSys : studies. pain, retinal detachment, cystoid
(Allergan, Dublin, Ireland) : is a macular edema.18
6mm gelatin and glutaraldehyde Decrease aqueous production
implant. It received its FDA by ablation of ciliary body Our experience with Ab
approval in 2016.15 The stent is interno trabeculotomy with
loaded in a single-use disposable 1) Endocyclophotocoagulation (ECP)- trabectome at SCEH:
injector with a 27-gauge needle. It is a cyclodestructive procedure Fifty seven eyes was operated for
Through a clear corneal incision, which allows direct imaging and abinterno trabeculotomy with
ablation of ciliary epithelium and trabectome by a single surgeon ( SD) at
thus decreasing the IOP. In contrast our institute.
to traditional cyclodestructive
procedure it limits the transfer of
laser energy to the surrounding
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 23
Subspeciality-Glaucoma
Distribution of Glaucoma No. of treatment paradigm has allowed for 9) Khaimi MA. Canaloplasty: A Minimally
eyes improved management of patients with Invasive and Maximally Effective
mild to moderate glaucoma. With better Glaucoma Treatment. J Ophthalmol.
Primary open angle glaucoma 31 safety profile, surgery may be proposed 2015;2015:485065.
earlier in the course of disease reducing
Congenital glaucoma 7 the need for topical medication and 10) Brusini P. Canaloplasty in open-angle
its ocular surface toxicity, lifetime glaucoma surgery: a four-year follow-
Juvenile open angle glaucoma 7 cost, and often limited compliance. up. ScientificWorldJournal. 2014 Jan
MIGS can be easily combined with 16;2014:469609.
Primary angle closure 5 routine phacoemulsification surgery
glaucoma and can be used in patients who have 11) Swamy R, Francis BA, Akil H, Yelenskiy A,
well-controlled IOP on drops, but who Francis BA, Chopra V, Huang A. Clinical
Pigmentary Glaucoma 2 desire drop independence. The field of results of ab interno trabeculotomy using
MIGS is expanding rapidly, thus adding the trabectome in patients with uveitic
Secondary glaucoma due to 2 promising newer options to the surgical glaucoma. Clin Exp Ophthalmol. 2020
systemic condition armamentarium of glaucoma surgeons. Jan;48(1):31-36.
Ocular hypertension 1 12) Dorairaj S, Tam MD. Kahook Dual
Blade Excisional Goniotomy and
Uveitic Glaucoma 1 Goniosynechialysis Combined With
Phacoemulsification for Angle-closure
Pseudo exfoliation glaucoma 1 Glaucoma: 6-Month Results. J Glaucoma.
2019 Jul;28(7):643-646.
Table 1: Showing distribution of different References
types of Glaucoma operated. 13) Grover DS, Godfrey DG, Smith O, Feuer WJ,
Montes de Oca I, Fellman RL. Gonioscopy-
1) Tham Y-C, Li X, Wong TY, Quigley HA, assisted transluminal trabeculotomy, ab
Aung T, Cheng C-Y. Global prevalence interno trabeculotomy: technique report and
of glaucoma and projections of glaucoma preliminary results. Ophthalmology. 2014
burden through 2040; a systematic review Apr;121(4):855-61.
and meta-analysis. Ophthalmology 2014;
121:2081– 2090. 14) Alcon announces voluntary global market
2) Gedde SJ, Herndon LW, Brandt JD, Budenz withdrawal of CyPass Micro-Stent for
DL, Feuer WJ, Schiffman JC; Tube Versus surgical glaucoma. Available at https://
Trabeculectomy Study Group. Postoperative www.novartis.com/news/media-releases/
Graph 1: Showing distribution based on the complications in the Tube Versus alcon-announces-voluntaryglobal-market-
severity of Glaucoma Trabeculectomy (TVT) study during five withdrawal-cypass-micro-stent-surgical-
years of follow-up. Am J Ophthalmol. 2012 glaucoma. Accessed November 30,2020.
Mean age of the patients was 48.2 ± 23.9 May;153(5):804-814.e1.
years with average follow up of 1 year. 3) Saheb H, Ahmed II. Micro-invasive 15) FDA approves Xen gel stent for glaucoma
No of eyes that underwent AIT with glaucoma surgery: current perspectives and - American Academy of Ophthalmology.
trabectome alone was 58% whereas future directions. Curr Opin Ophthalmol. https://www.aao.org/headline/fda-
42% underwent combined surgery 2012 Mar;23(2):96-104. approves-xen-gel-stent-glaucoma. Accessed
(AIT with trabectome combined with 4) iStent® Trabecular Micro-Bypass Stent Nov 2020.
phacoemulsification with intraocular System [directions for use/package insert].
lens implantation). Laguna Hills, CA: Glaukos Corporation; nd. 16) De Gregorio A, Pedrotti E, Stevan G,
At one-year follow-up IOP reduced Last accessed: 30 Nov 2020. Available from: Bertoncello A, Morselli S. XEN glaucoma
from 23.39 ± 10.18 mmHg to 14.82±4.16 https://www.accessdata.fda.gov/cdrh_docs/ treatment system in the management of
mmHg (36.64% reduction) and pdf8/p080030c.pdf refractory glaucomas: a short review on trial
glaucoma medication decreased from 5) iStent inject Trabecular Micro-Bypass data and potential role in clinical practice.
2.18 ± 1.32 to 1.91± 1.57. One eye had System (Model G2-M-IS) – P170043. Last Clinical Ophthalmology (Auckland, N.Z.).
hyphema requiring anterior chamber accessed: 30 Nov 2020. Available from: 2018 ;12:773-782.
wash and one eye had increased https://www.fda.gov/medical-devices/
anterior chamber reaction at 1month. recently-approved-devices/istent-inject- 17) Uram M. Endoscopic cyclophotocoagulation
No vision threatening complication trabecular-micro-bypass-system-model-g2- in glaucoma management. Curr Opin
was observed. Six eyes, required m-p170043 Ophthalmol. 1995 Apr;6(2):19-29.
additional glaucoma surgeries to lower 6) Yook E, Vinod K, Panarelli JF. Complications
the intraocular pressure. We found of micro-invasive glaucoma surgery. Curr 18) Lin S. Perspective: endoscopic
that AIT with trabectome is a safe and Opin Ophthalmol. 2018 Mar;29(2):147-154. cyclophotocoagulation. Br J Ophthalmol.
effective procedure and can be easily 7) Pajic B, Pajic-Eggspuehler B; Haefliger, 2002;86:1434–1438.
combined with cataract surgery. I. The High-frequency Deep Sclerotomy
Glaucoma Procedure. European Ophthalmic Corresponding Author:
Conclusion Review, 2012;6(1):20-20
The introduction of microinvasive 8) Hydrus® Microstent - P170034. Last Dr. Suneeta Dubey
glaucoma surgery to glaucoma accessed November 30,2020. Available Medical Superintendent, Head-Glaucoma Services,
from: https://www.fda.gov/medical- Dr. Shroff’s Charity Eye Hospital,
devices/recently-approved-devices/hydrusr- New Delhi, India
microstent-p170034
24 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Lasers in Glaucoma
Harsh Kumar, MD, Nirmala Sudhamala, MS, Mithun Thulasidas, MS,
Glaucoma Services , Centre for Sight
B-5/24, Safdarjung Enclave , New Delhi- 110029 India
Abstract: Laser procedures have been widely used for glaucoma treatment in addition to medications and incisional surgery to
slow vision loss and achieve optimal intraocular pressure. Rapid advancement in laser technology and instrumentation have
led to new treatment techniques as well as refinements of old ones. This article describes commonly performed laser procedures
used in the treatment of glaucoma patients.
Keywords: Lasers, glaucoma, peripheral iridotomy, trabeculoplasty, gonioplasty, cyclophotocoagulation
Though lasers have been used for many Indications complications along with the fact that
years for the treatment of glaucoma, 1. Primary angle closure suspect the procedure may require multiple
absolute indications and use of the sittings. An appropriate consent
procedures need to be considered before (PACS): A case is defined as PACS if form must be signed by the patient
their application. Lasers have made one cannot visualise the posterior after having read all the possible
the task of treating glaucoma simpler, trabecular meshwork (TM) for 180° complications. One must enquire
and these procedures are being used to 270° on gonioscopy. However, whether the patient is on anticoagulants
routinely by most ophthalmologists on indentation, this opens up which may cause excessive bleeding
even at a very basic level. fully without any peripheral during/after an iridotomy. These may
anterior synechiae. Many Indians need to be stopped in consultation
Primary laser procedures for would qualify for this and when with the doctor who had started these
glaucoma are neodymium: yttrium- one is not sure which cases to do medications be a cardiologist or a
aluminum-garnet (Nd:YAG) then those who cannot come for neurologist. The intraocular pressure
laser peripheral iridotomy (LPI), regular follow up, require frequent (IOP) should be well controlled on
dilatation, positive provocative medications, and if it is a case of an
argon laser trabeculoplasty (ALT), test, family history of primary acute attack of angle closure, then one
selective laser trabeculoplasty (SLT), angle closure (PAC)/ primary angle may have to use systemic acetazolamide
iridoplasty or gonioplasty, diode laser closure glaucoma (PACG), one- or intravenous mannitol so that the
cyclophotocoagulation, suturolysis, eyed with PACS, fellow eyes of procedure is performed on an eye with
bleb remodelling, synechiolysis and established PAC/ PACG are chosen. as well-controlled IOP as possible. One
Nd:YAG hyaloidotomy besides other In confusing cases, one can resort to drop of pilocarpine 2% is instilled into
less commonly used procedures. This darkroom prone provocative test. the eye 15min before treatment. If there
article aims to provide the basic steps of 2. Therapeutic purpose to relieve is not enough miosis or the iris does
when and how to do a laser procedure an acute angle closure attack and not look stretched, then one can put
by any ophthalmologist. relieve iris bombe due to secondary additional pilocarpine eye drops.
angle closure.
Nd:YAG laser peripheral The patient is comfortably seated on
iridotomy (LPI) Contraindications the laser, and the eye is anaesthetised
Neovascular glaucoma followed by insertion of an Abraham
Almost 30-50% of our glaucoma Non-pupillary block or lens-induced lens which will have a peripheral
population is related to angle closure angle closure button in the goniolens so that the laser
in various regions. The purpose of an Drug-induced secondary angle closure beam can be magnified and shifted to
iridotomy is to negate the element of periphery along with stabilizing the
iris bombe and pupillary block. If the Procedure eye. The site is chosen, and appropriate
angle is fully blocked, then it is not energy is set to penetrate the iris. The
likely to help. Also, if the angle closure The patient and relatives must be surest sign that the iridotomy has been
is related to lens swelling, plateau iris, explained the need for the procedure, completed is that there is a sudden gush
or choroidal swelling related to drugs the procedure itself and the possible
like topiramate, the LPI is not useful.
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 25
Subspeciality-Glaucoma
of aqueous along with deepening of the closure due to inflammation or excess progression was seen in 38.9%
chamber. Retro illumination is not a pigment release. of eyes among those who had
sure sign as this could be positive even undergone LPI at baseline compared
with fibres plugging the flow. Complications with 23.1% of eyes that had no
intervention.2 The significance of
Energy to be used: One should aim a) Haemorrhage this complication comes when
to finish the iridotomy in two to four we understand that we are doing
shots. If the iris is very thin like in The commonest complication this procedure in a large number
lightly pigmented eyes or one with a and rather an accompaniment of of PACS eyes which are otherwise
deep crypt, then a single shot could Nd:YAG laser iridotomy is some practically untouched and normal
also suffice. However, if the iris is thick, extent of haemorrhage from the thus they may not develop cataract
then more shots or even more sittings iris. Usually, it is in the form of a for a significantly longer time than
could be required. One should start trickle which looks quite major if LPI is done. The onus lies on us to
with 4-6mJ in a thin iris and with full when we are looking through the prove that LPI is really required in a
energy in a thick iris. Once a lamellar magnification of the lens. If it is particular case.
hole is made, one can reduce the energy large, one should immediately
to avoid hitting the lens. press the gonioscope for a short d) Glare
while around ten seconds when
Size of iridotomy should be around 150- this subsides by itself. Sometimes Glare, along with diplopia, may be
200μm as a smaller one is likely to close it can result in a full hyphema even a problem in few of the patients,
while a larger one is likely to give glare. requiring anterior chamber wash. It especially if the size of the
is for this reason that we always ask iridotomy is large. However, it is
Site: Currently, one can do LPI at any if the patient is on a blood thinner rarely of any significance in most of
peripheral site where iris is thin, or a and require them to stop it five the instances and settles down.
crypt is present. Also, one should aim at days prior in consultation with the
an area where chamber is deep so that doctor who started the medicine for e) Corneal decompensation
the cornea is safe. Avoid too peripheral blood thinner.
an LPI since that can injure the ciliary Corneal problems along with
body, and also it is more challenging b) IOP elevation the possibility of long term
to perform due to pannus and arcus in decompensation are highlighted
many eyes. Some element of pressure elevation in literature in a significant way
is likely to occur, and this will though we have seen only very
Difficult LPI: In case the iris is very depend on the level of initial IOP, few such cases. Such reports are
thick, and an iridotomy seems difficult, the amount of pigment dispersed, more common in the Eastern
then the following steps should be the extent of haemorrhage countries, possibly because of
undertaken. and level of angle closure. The shallower chambers and a higher
maximum peak of IOP post-laser incidence of angle closure in their
• Explain to the patient that more is likely to come at or within four population. They do report such
than one sitting may be required for hours of the iridotomy.1 It is for this decompensation even after 8 years
the laser procedure. The pupil must reason that an additional pressure- after the LPI. The various causes
be constricted adequately with lowering drug is started before attributed are direct focal injury,
pilocarpine 2% two to three drops performing an LPI in a naive case thermal damage, mechanical shock
to stretch out the iris. Use argon and in those where anti-glaucoma waves, iris pigment dispersion,
laser 300μm spots with 300mW medications are already being used, transient rise in IOP, inflammation,
power and 0.5sec duration burns an additional medication can be turbulent aqueous flow, time‐
to create a circle in the peripheral started. It is always good to perform dependent shear stress on
iris, also called the Drumhead LPI on an eye with well-controlled endothelium, chronic breakdown
technique. This allows the iris to pressure. of blood–aqueous barrier, and
become taut in the centre of this damage from bubbles that settled
circle so that when Nd:YAG shot is c) Cataract formation onto the endothelium.3 The usual
fired, the hole is easily made. endothelial burns seen during the
There are conflicting reports procedure disappear quickly, rarely
Postoperatively we like to give steroid- regarding the extent and rapidity leaving any footprints.
antibiotic combination for four days of cataract formation post-LPI. In
but extended if required. Some doctors the Chennai Eye Disease Incidence f) Subluxation of lens
continue pilocarpine 2% two to three Study, six years after their baseline
times a day in case there is a fear of evaluation there was significant Subtle subluxation of the lens due
cortical cataract progression to use of excessive energy while
following LPI for PACS. Cataract performing the LPI has been
26 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
reported though many times it is release or gas bubble formation, patients who are just diagnosed and
detected during lens extraction charring of iris, or production of “pop” do not want medications, are allergic
itself. sound, the energy should be reduced. to medications or those who are on
Approximately 24 spots are placed over full medications but still uncontrolled
Iridoplasty/ gonioplasty 360° (six to eight spots placed in each and not wanting surgery. The IOP
Initially propagated by Krasnov, it is a quadrant), leaving approximately two lowering in Indian eyes can be expected
technique which uses the coagulative spot diameters between each spot. The to be in the range of 3-6mmHg, but the
laser to produce peripheral scarring in spots can also be applied without any effect in Indian eyes is not long-lasting
the iris to stretch open the angle. contact lens. sometimes waning as early as six
months to a year.
Indications Complications
Mechanism of action:
1. Plateau Iris Syndrome Mild iritis may be noticed which
2. Acute attack of angle closure resolves over a week. Diffuse corneal It induces a mechanical effect by causing
endothelial burns may occur if it increased TM tension circumferentially,
glaucoma (ACG) not responding to is performed on patients with very pulling the outer layers of the TM, and
medication where LPI is difficult to shallow peripheral anterior chamber. hence increasing the outflow facility.
perform due to boggy iris and mid They can be minimized by placing an
dilated pupil. initial contraction burn more centrally Selective laser
3. Chronic angle closure on maximum on the iris, before placing the peripheral trabeculoplasty (SLT)
medical therapy where surgery is burn (criss-cross iridoplasty). In all the This procedure is one of the later
not possible. cases, the endothelial burns disappear additions to the armamentarium of the
4. Acute phacomorphic glaucoma to within several days. A transient rise in glaucoma specialist to decrease IOP in
control pressures till the surgery is IOP may occur and must be looked for. cases of OAG and ocular hypertension
performed. There may be iris atrophy which can be along with selective cases of ACG.
avoided using the lowest laser power This technique requires a specialized
Procedure and not allowing the laser marks to laser machine. SLT selectively target
become confluent. pigmented TM cells while sparing
After obtaining informed consent, adjacent non pigmented cells and
topical pilocarpine 2% is applied once One must understand that in many collagen TM beams from collateral
or twice to stretch the iris maximally. situations the effect of laser gonioplasty thermal damage which can preserve
The procedure is performed under may be temporary so that a close follow the structural integrity of the TM.
topical anesthesia only if a gonioscope up is desired besides the need to repeat Selective targeting of pigmented TM
is necessary to reach the most the procedure. cells can be obtained with a pulse
peripheral parts. The argon laser (or duration of 3ns or less. Therefore, the
any coagulative laser like frequency- Argon laser trabeculoplasty technique has been named SLT, which
doubled Nd:YAG green laser) is set to (ALT) delivers approximately 1% of the total
produce contraction burns (500μm spot A technique of applying low-grade energy used by ALT. Clinically, the
size, 0.5–0.7sec duration, and initially burns in the anterior trabecular parameters used in SLT are too short
power is set at 240mW). In the direct meshwork using a coagulative laser for melanin (chromophore) to convert
technique, which uses an Abraham was first described by Wise and Witter the electromagnetic energy to thermal
lens, the laser energy is applied in 1979. energy, and hence no heat is generated.4
perpendicular to the peripheral iris.
With the indirect technique, which uses Indications: Indications:
a single-mirror gonioscope, the beam
is directed at a low angle of incidence The indications of this technique include The use of SLT is the same as we have
toward the peripheral iris and angle. open angle glaucoma (OAG), ocular defined in the ALT section. The most
It is useful to allow a thin crescent of hypertension, and in some situations important use is in pregnancy to
the aiming laser beam to overlap the in angle closure glaucoma as well. The lower IOP when no medication is safe.
sclera at the limbus, and the patient most important use of this procedure is Those not wanting any medication
is asked to look in the direction of the during pregnancy when the use of any when first diagnosed as OAG or
beam to achieve more peripheral spot anti-glaucoma medication is fraught ocular hypertension are other likely
placement. The energy is increased in with danger for the foetus, and one may candidates. Those who are on maximum
40 mW increments until adequate iris lower the IOP to tolerable levels using medications, yet uncontrolled may also
stromal contraction is noted. Lighter just this procedure. In OAG and ocular undergo this procedure though the
irides generally require more power hypertension, the procedure is used in results are not as good.
than darker ones. If there is pigment
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 27
Subspeciality-Glaucoma
Mechanism of action: treatment, with approximately 60% said that there is minimal or no tissue
of eyes achieving an IOP reduction of destruction, minimal inflammation,
SLT is based on the concept of selective 30% or more.6 Long term effect of ALT no additional vision loss and can be
photothermolysis, which ensures diminishes over time and the 5-year done in seeing eyes. Also, it has been
confinement of thermally mediated success rate is reported to be about said it can be used safely and effectively
radiation damage to a selected 50%.7 Long term effectiveness of SLT in all forms of glaucomas including
pigmented cell population within seems to show similar results.8 One can refractory glaucomas with no dreadful
tissue with no collateral damage.5 expect a general reduction of 3-6mmHg complication.
in IOP which may last variably. The
Procedure most significant advantage of SLT over Mechanism of action:
ALT is that the procedure is repeatable
The SLT devices currently available as the tissue damage is negligible. The This laser lowers IOP by increasing the
use a Q switched, frequency-doubled, procedure has not become popular in existing uveoscleral outflow without
532nm Nd:YAG laser, 400 µm diameter India because of the cost of the machine photocoagulating tissue. Micropulse P3
spot size and delivers energy in 3 ns. and limited long term success. (MP3) laser shortens the longitudinal
The patient is anaesthetised with ciliary muscles, thereby opening
procaine in the eye to be lasered, is Complications : the schlemm’s canal and TM spaces
seated at the slit lamp system, a Latina and increasing aqueous outflow by
SLT single mirror goniolens (Ocular Though the procedure is very simple conventional pathway.
Instruments, Bellevue, WA, USA) with and safe, side-effects like redness,
a methylcellulose coupling medium is discomfort, and anterior chamber Procedure:
placed on the eye. The laser is focused reaction in the first week after SLT
on the TM using the Helium-Neon are possible. Transient IOP spike, The fibre optic tip of MP3 probe is
aiming beams. An initial energy level iritis, hyphema, macular edema, 600µm in diameter and protrudes
of 0.7-0.8mJ is typically used (with transient corneal thinning, changes in 0.4mm from the handpiece. Under
typical settings of 0.4-1.2mJ) for lightly endothelial cell count, foveal burn, and peribulbar anaesthesia, the probe tip
pigmented TM. The energy level used corneal haze have been reported but are is positioned at 3mm posterior to the
is titrated to the degree of trabecular rarely of any consequence. limbus and performed. The laser contact
pigmentation, that is, with the greater probe is placed over conjunctiva with
pigmentation, less energy is required. Micropulse transscleral its notch at the limbus and flat surface
In more heavily pigmented TM, around cyclophotocoagulation facing the eyelid. Laser power is set at
0.6mJ initial energy may be used. 2000mW with a duty cycle of 31.3%
If cavitation bubbles (“champagne Micropulse diode laser in glaucoma is a (MP3) and 25% (Quantel Medical,
bubbles”) appear, the laser energy is newer advance in glaucoma treatment. Supra810, SubCyclo). It delivers laser
reduced by 0.1mJ increments until It is noninvasive, nondestructive, for 0.5ms of “on time” where the ciliary
no bubble formation is observed supposed to be sight preserving sub- body is targeted and then 1.1ms “off
and the treatment is continued at threshold laser procedure which is time”. This allows tissue to cool down
this energy level. If no cavitation repeatable with minimal follow- between the laser shots reducing
bubbles are observed at the TM after up care and variable IOP control. It thermal damage. The laser is applied
laser application, the pulse energy is is a 810nm diode laser from Iridex in a sweeping motion in superior and
increased by increments of 0.1mJ until corporation/ Supra 810/ SubCyclo/ inferior quadrants for 160sec (80sec
bubble formation is seen and then Quantel Medical similar to trans-scleral each) avoiding 3 and 9 o’clock.
decreased as described above. An energy cyclophotocoagulation (TSCPC) laser.
level just below that of bubble formation Postoperative pain, inflammation and
is then maintained. Confluent spots are Traditional TSCPC is used in end-stage infection are managed with topical
applied for best results. A total of 360° disease as it causes tissue destruction, steroids tapered over 3-4 weeks. All anti-
of the TM is lasered (100 spots; 25 spots inflammation and resultant vision glaucoma drugs should be continued
per quadrant) except in an eye with a loss. TSCPC delivers near-infrared for at least a month after MP3 treatment
heavily pigmented TM when 180° is laser in a continuous wave fashion in and slowly withdrawn one by one
done first and the remaining 180° later, contrast to which micropulse delivers depending on IOP. The micropulse
if needed. The spots need not be well laser in pulse with “on and off time” treatment can be repeated with an
focused but are placed in the area of the reducing focal heating and burning interval of 2-3 months.
trabecular meshwork. of tissues. These short pulses allow
the tissue to cool between pulses, Complications:
90° SLT is generally not effective, and thereby alleviating cumulative or
360° SLT appears to be an effective continuous thermal energy. It has been The potential complications like loss
of visual acuity, chronic uveitis, retinal
28 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
detachment, retinal tears, neurotrophic suffices. After this, digital pressure on and better tolerated by the patient
corneal changes, pupil enlargement or the eye should be used, which forces than cyclocryotherapy though above-
atonia, and hypotony are known to the aqueous through sclerostomy and mentioned complications can occur in
occur.9 Eyes with refractory, complex elevates the bleb. these as well.17,18 Beckman et al. were
glaucoma and past glaucoma surgery the first to report on TSCPC using ruby
may experience vision loss unrelated Complications : laser (693nm).19 Since then, several
to the procedure.10 It is, therefore, wavelengths have been used. The most
cautioned that this procedure is Complications include conjunctival frequently used lasers are the 810nm
never a replacement of conventional perforation, flat anterior chamber, diode laser.20-22
trabeculectomy, and should be used hyphema, iris incarceration, bleb
with great caution in seeing eyes. leak, prolonged hypotony due Indications :
to overfiltration, and malignant
Laser suture lysis glaucoma.12,13 One should watch these As previously indicated, refractory
cases closely postoperatively and glaucomas like neovascular glaucoma,
The technique to create a greater give antibiotics post laser to prevent post-penetrating keratoplasty
outflow from the trabeculectomy infection as there may be a small area glaucoma, post-traumatic glaucoma,
requires the release of the sutures in the of leak. post-retinal detachment surgery
scleral flap. Though a large number of
surgeons are putting releasable sutures glaucoma, silicon-oil-induced
which can be just pulled out, others glaucoma, inflammatory glaucoma,
with access to Argon laser have the Laser cyclophotocoagulation
option to perform argon laser suture
lysis (ALS) which was first described by In a situation where performing a aphakic/pseudophakic glaucoma,
Hoskins and Migliazzo in 1984.11 refractory pediatric glaucoma, after
routine glaucoma surgery, be it a multiple failed surgeries, in the presence
It can be performed in the early
postoperative period, a few days or weeks trabeculectomy or a shunt surgery of severe conjunctival scarring, for
after the surgery. If trabeculectomy is
augmented with antimetabolite, it can is extremely difficult, surgeons have pain relief in a painful blind eye due
be done 2–3 weeks after the surgery or
later, as antimetabolites delay wound been resorting to cyclodestructive to elevated IOP, as an urgent means to
healing.12 However, delaying the
suturolysis to beyond 3 weeks may procedures. These are usually painful lower IOP when access to surgery is
negate the benefit as the scleral flap
refuses to open up due to fibrosis. Many eyes on maximum medications limited and for patients medically unfit
a time, it may be required to do it even
earlier as the pressure does not come with little possibility of vision. The for surgery.23-37
down even by massage.
cyclodestructive procedure used very
Procedure:
commonly in our country includes Mechanism of action:
The conjunctiva is first blanched by
using phenylephrine drops two to three cyclocryotherapy, which requires a Various theories have been described
times at an interval of ten minutes. A like the destruction of the ciliary
lens (Hoskins or Blumenthal or Zeiss nitrous oxide cylinder and a glaucoma epithelium resulting in decreased
four mirror) is used to enable clear aqueous production, destruction of
visualization of the subconjunctival cryoprobe costing very little. However, ciliary blood vessels and coagulative
suture, and gentle pressure with the lens necrosis leading to ciliary body
blanches the overlying conjunctival it is an extremely painful procedure ischemia, intraocular inflammation
vessels before the procedure. The which is thought to cause short-term
parameters for the treatment depend and hence evolved the diode laser decrease in IOP, creation of a trans-
on the bleb wall thickness and the type scleral flow similar to cyclodialysis or
of laser (frequency-doubled Nd:YAG, cyclophotocogulation procedure an increased uveo-scleral outflow.38-40
argon or diode) used. For argon Laser,
a spot size of 50µm, power of 600- requiring a specific machine and a
1000mW and duration of 0.1–0.2sec
probe.
In recent years, the spectrum of Trans-scleral
cyclophotocoagulation has expanded cyclophotocoagulation
from end stage glaucoma to glaucoma (TSCPC)
in patients with good visual acuity. Procedure:
Cyclophotocoagulation procedures
have gained acceptance, even in Informed consent should be taken
pediatric glaucoma. Different lasers explaining the risks to the patient
have been used for this purpose besides before the procedure. It is done
diode, which includes ruby, Nd:YAG, under retrobulbar or peribulbar
argon and krypton laser. anesthesia. For children, it is usually
done under general anesthesia, and
Compared to cyclophotocoagulation, this is augmented by a retrobulbar
cyclocryotherapy is limited by or peribulbar block to prevent
significant intraocular inflammation,
severe postoperative pain, hypotony,
and phthisis.14-16 Laser cycloablation
is considered to be more effective
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 29
Subspeciality-Glaucoma
postoperative pain. An 810nm Laser hyaloidotomy/ pupil as it invariably bleeds while
semiconductor diode laser is used making cuts in the iris and makes the
with a G probe. The probe is a 600μm vitreolysis media cloudy. It takes multiple sittings
diameter quartz fibre with a spherical to achieve the objective of dilating this
protruding tip oriented by the footplate In cases of malignant glaucoma where bound down pupil, and one may not be
of the handpiece. It is designed to centre the patient presents with very high able to do it completely if the synechiae
treatment 1.2mm behind the limbus. IOP, extremely shallow chambers and are dense and the entire underside of
The handpiece footplate part which situation not resolving with atropine the iris is plastered onto the lens. After
comes into contact with the sclera is and maximum medical therapy one each sitting, the pupil is to be dilated
spherically curved to match the contour can try Nd:YAG procedure in aphakic or with phenylephrine-cyclopentolate
of the sclera. The anterior curved pseudophakic eyes, to break the trapped combination to move the area of the
edge is designed to match the limbus. areas of aqueous behind a slot vitreous pupil where the synechiae have been
Trans‐scleral transillumination is phase. One has to initially perform a successfully removed. Steroid eye drop
used to demonstrate the position of posterior capsulotomy going till the along with dilating drops are given
the ciliary body because its location edge of the intraocular lens (IOL) and post-laser therapy for a week.
varies considerably, which may be so then shoot the laser in the mid-cavity to
especially in buphthalmic eyes.30 The break the pockets of trapped aqueous.45 Laser management of
power is kept between 1500-2000mW Several studies have reported success overhanging or enlarged
with a time duration of 2sec. A “pop” with this procedure in eyes refractory to blebs
sound denotes tissue disruption. If medical therapy.46,47 In a pseudophakic Excess filtration can lead to blebs which
there is no “pop” sound, the power is patient with a large IOL optic, the spread to the nasal and the temporal
increased by increments of 100mW till outcome can be improved by making aspect with boggy conjunctiva,
the “pop” is heard, following which the the capsular opening through a dialing hypotony resulting in hypotonic
power is reduced by 100mW. About hole, if present.48 maculopathy besides causing
18–20 laser spots for 360° and about dysesthesia, irritation and cosmetic
10–12 for 180° (spots per quadrant) Deepening of the anterior chamber is blemish. Similarly, many chronic
are applied. One must avoid sites of seen immediately or within 24 hours blebs may not be over filtering but are
previous filtering surgery/tubes, areas with definite relief of the symptoms. elevated resulting in a dellen formation
of thin sclera, and the 3 and 9 o’clock One should proceed with vitrectomy if in the cornea adjacent to it along with lid
positions (to avoid the long posterior the above procedure does not work. movement problems and dysesthesia.
ciliary nerves).41 We developed a technique in which
Iridolenticular synechiolysis we paint the conjunctiva in question
After the procedure, patching of the eye with gentian violet. A photocoagulative
is done for approximately 6 hours till the This procedure is carried out in cases laser is used. The spot size is kept at
effect of the local anesthesia wears off. of secclusio pupillae, where the iris 300–500μm with 0.3-5W power and
Topical antibiotic-steroids and topical does not allow for visualization of the 100ms timing such that a superficial
cycloplegics are prescribed, which are posterior segment.49 charring of the painted conjunctiva
tapered as the inflammation subsides. takes place without any perforation.50
The pre laser glaucoma medications The pupil is dilated using topical This procedure may not work in all
are continued, depending on IOP mydriatics and though due to the situations, and one may have to go in
response. Analgesics (nonsteroidal bound down pupil, the pupil will not for a surgical revision.
anti-inflammatory drugs) may need to dilate, yet the area is brought under
be prescribed for the pain. The patient stretch. After putting two to three drops Declaration of competing
is followed up at day 1, 1 week, 1 month, of dilators in half an hour, proceed to interest
according to the response to treatment. apply a minimum YAG energy of 0.5mJ The authors have no financial
Additional laser therapy, if needed, and focus the spot just anterior to the disclosures.
should be considered after 1 month. synechiae on the side of iris away from
the lens such that the plasma generated Acknowledgements
Complications : when the Nd:YAG shot is fired, helps None
sweep off the synechiae. If this does not
Pain can occur but is usually transient. work, one can go closer and directly aim References
Iridocyclitis (42%) is common after the at the synechiae and cut the synechiae.
procedure, due to a breakdown of the One can increase the energy sequentially 1. Kumar H, Sood NN, Kalra VK. Pressure
blood-aqueous barrier.42-44 Transient rise but rarely exceeding 2mJ, as that is liable dynamics after mode-locked Nd:YAG
of IOP can occur. to cause lens damage. The procedure
starts from the 6 o’clock position and
proceeds upward on either side of the
30 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
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Surv Ophthalmol 2015;60:36-50. diode lasers. Am J Ophthalmol secondary intervention following
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9. Shields MB, Shields SE. glaucoma. J AAPOS 2009;13:379-83.
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cyclophotocoagulation: a long-term MS, Lin SC, Netland PA, et al. 32. Ness PJ, Khaimi MA, Feldman RM,
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Malignant glaucoma following argon
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Subspeciality-Retina
after laser iridoplasty: IMPACT study. Br transscleral diode laser capsulotomy as a primary treatment.
J Ophthalmol 2017;101:886-91. cyclophotocoagulation treatment for Eye (Lond) 1993;7(Pt 1):102-4.
48. Melamed S, Ashkenazi I, Blumenthal
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42. Schuman JS, Bellows AR, Shingleton 49. Kumar H, Ahuja S, Garg SP. Neodymium:
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38. Walland MJ. Diode laser Director, Glaucoma Services, Centre for Sight
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follow up of a standardized treatment Liu A, et al. Diode laser transscleral New Delhi 110029
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39. Schubert HD, Agarwala A, Arbizo V. closure eyes: The longterm result. BMC
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Invest Ophthalmol Vis Sci 1990;31:1834- NeodymiumYAG laser therapy to the
8. anterior hyaloid in aphakic malignant
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40. Pantcheva MB, Kahook MY, Schuman Ophthalmol 1984;98:137-43.
JS, Noecker RJ. Comparison of acute
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Ophthalmol 2007;91:248-52. 1986;104:1464-6.
41. Gupta V, Agarwal HC. Contact 47. Little BC, Hitchings RA. Pseudophakic
malignant glaucoma: Nd:YAG
32 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Role of Lens Extraction in Primary
Angle Closure Disease
Shefali Parikh, Rajul Parikh
Shreeji Eye Clinic & Palak’s Glaucoma Care Centre, Samrat Bldg, Andheri (E),
Mumbai, India
According to estimates for 2020, smaller eye.[4,5] Removal of the lens can intervention aims to prevent in order to
primary angle closure glaucoma deepen the anterior chamber and relieve provide guidelines for the current role
(PACG) affects about 23 million people the crowding of the angle. Improvement of CLE in PACD. Clear lens extraction
and is responsible for half of the in anterior chamber depth and angle is being advocated for primary angle
blindness caused by glaucoma [1]. PACG contour following phacoemulsification closure disease (PACD). It is important
has a high population-attributable has been demonstrated.[6–8] that this advocacy should be based on
risk percentage, which means that if There are very few peer-reviewed a sound, peer-reviewed evidence base.
treated at an early stage a significant reports of lens extraction in PACD This review attempts to establish the
proportion of PACG-related blindness is that have included clear lenses: two of extent of that evidence and provide
preventable .[2,3] these dealt with the acute or subacute some management guidelines.
setting and none specifically assessed
The clinical spectrum of primary angle the efficacy of clear lens extraction Role of Cataract Surgery in
closure disease (PACD) includes primary using modern phacoemulsification PACD
angle closure suspect (PACS), primary surgery as a treatment for PACG.[9–11] A 1. Acute Primary Angle Closure:
angle closure (PAC), PACG and acute 2006 Cochrane review found only two
primary angle closure (APAC). ‘Fellow articles suitable for consideration and Lam et al., in a prospective randomized
eye’ refers to the second eye of a person discussion was ultimately limited to trial, compared the effects of primary
who has developed APAC in one eye. one of them: the review concluded that phacoemulsification/IOL versus LPI in
Conventional management of PACD despite the biological plausibility of the prevention of IOP rise in patients
usually starts with a laser peripheral benefit there was no published evidence soon after APACs were aborted.[13]
iridotomy (LPI) but incisional surgery for the effectiveness of lens extraction Thirty-one patients were recruited in
may be needed if other noninvasive in chronic PACG.[12] A comprehensive each arm. At 18 months, the early phaco/
methods like medical treatment or review of the literature to 2007 of the role IOL group demonstrated a significantly
laser iridoplasty (ALPI) do not work. of the lens in angle closure glaucoma lower prevalence of IOP elevation,
Depending on the state of control of advised that ‘the role of lensectomy required fewer glaucoma medications
intraocular pressure (IOP), existing in the management of PACG has not to maintain IOP at < 21 mmHg, more
cataract is usually assessed using been established’ and did not provide significant degrees of open angle, and
separate surgical indications. Cataract any clinical guidelines.[5] Later RCTs less extensive peripheral anterior
surgery is a highly cost-effective have reported lens extraction in APAC synechiae (PAS) on gonioscopy
intervention for restoring vision for and PACG; [13,14,15] a recent overview has compared to the LPI group. However,
many patients that also has appeal as provided a different perspective on the there were no statistically significant
a surgical treatment in angle closure. role of clear lens extraction in PACD by differences in visual acuity, vertical cup
Most ophthalmologists are competent extrapolating the findings from cataract to disc ratio (VCDR), median deviation
cataract surgeons and, when indicated extraction to this group of diseases. [16] (MD), and pattern standard deviation
for visual symptoms, the benefits to We review the literature on the role (PSD) on the visual field (VF) between
angle and IOP are welcome bonuses. of lens extraction (including CLE) the two groups. None of these patients
in PACD and combine this with the required further surgery to control IOP.
The shallowing of the anterior chamber estimated probability of the events the
in PACD is caused by a thicker lens in a Later, Husain et al. performed an RCT
more anterior position, frequently in a that compares the 2-year efficacy of
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Subspeciality-Glaucoma
primary phaco/IOL with LPI in the early clear lens extraction in PACG and extraction group required less number
management of APAC and coexisting they also included quality-of-life of medications (mean 0·4 [SD 0·8] vs.
cataract.[17] Patients with APAC that questionnaires (directly patient-related) 1·3 [1·0]). There was also a difference
had the IOP lowered to ≤30 mmHg as Primary measure. The other primary between groups in need for further
by medications within 24 h were endpoints were IOP, and incremental surgery to control IOP (one patient in
treated either with LPI 72 h after the cost-effectiveness ratio per quality- the clear-lens extraction group vs. 24
medical treatment or by phaco/IOL 5 adjusted life-year gained 36 months patients in the laser iridotomy group);
to 7 days after the IOP was lowered. after treatment. Four hundred nineteen of the 24 patients in the laser iridotomy
Eighteen patients and 19 patients were patients were randomized and followed group who had further surgery, 16
randomized to LPI and the primary up for three years, of whom 208 were (67%) underwent cataract surgery.
phaco/IOL group, respectively. Failure assigned to clear-lens extraction and However, the need for some cataract
was defined as uncontrolled IOP (22 211 to laser iridotomy. 351 (84%) had operations within three years is not
and 24 mmHg on two occasions (one- complete data on health status and surprising, and this finding should
month interval) or IOP ≥ 25 mmHg 366 (87%) on IOP. The study details not be interpreted as an increased
on one occasion after week 2) loss are already published. Authors have occurrence of an unfavorable outcome
of light perception attributable to concluded that small but significant in the laser iridotomy group. The study
glaucoma, the necessity for further advantage of primary clear-lens did not look into corneal endothelial
operative intervention for glaucoma, extraction over laser iridotomy for all cell loss after phacoemulsification,
or APAC’s recurrence. At 2-year, measured outcomes. The mean health one of the study’s limitations. Various
there was significantly less treatment status score (0·87 [SD 0·12]) on the publications have shown mean
failure in the phaco/IOL group (2/19 European Quality of Life-5 Dimensions corneal endothelial cell loss after
[10.5%]) compared to the LPI group (EQ-5D) questionnaire was 0·052 higher phacoemulsification in patients whose
(7/18 [38.9%]; P = 0.029). Six patients (95% CI 0·015 to 0·088, p=0·005) and eyes have shallow chambers, and short
in the phaco/IOL group required IOP- mean IOP (16·6 [SD 3·5] mm Hg) 1·18 axial lengths—both features of primary
lowering medications, of which two mm Hg lower (95% CI −1·99 to −0·38, angle closure can be as high as 19%.
were considered failures because of p=0·004) after clear-lens extraction than
high IOP. Whereas 7 out of 18 patients after iridotomy. The study results can be applied only
were classified as failures in the LPI to patients with primary angle closure
group – 6 underwent combined phaco- This trial is clinically relevant because and IOP higher than 30 mm Hg—
trabeculectomy with Mitomycin C, it addresses a topic with widespread who represent a minority of patients
and 1 underwent repeated LPI because practical implications, especially in in the PACD group. To expect and to
of APAC recurrence (the initial LPI a country like ours, where PACD is extrapolate these results to the PACG
was noted to have closed). Another six a significant health issue. Patients group, especially with moderate and
patients in the LPI group underwent undergoing clear-lens extraction advanced glaucoma, is beyond the data
cataract surgery because of decreased became emmetropic (final refraction and impractical.
visual acuity and were not for IOP 0·08 [SD 0·95]), whereas those assigned
control – they were not classified to laser iridotomy remained hyperopic While not yet sufficient to justify using
as treatment failure. Both studies (0·92) as they were at baseline. clear-lens extraction to treat all patients
concluded that phaco/IOL resulted in Uncorrected visual acuity, therefore, with primary angle closure with or
a lower rate of IOP failure at two years improved significantly for distance and without glaucoma, the findings of this
compared with LPI if performed within near vision in the clear-lens extraction trial could have positive implications
the first week in patients with APAC group only, which most probably for areas where angle closure is most
and coexisting cataract. was associated with improvements prevalent, particularly Asia, or where
in patient-reported outcome health-care resources are scarce, and
2. In Chronic PACD Clear Lens questionnaires. Most probably, this patients might not have easy access to
Extraction: (EAGLE Study) improvement in refractive error in the medications and monitoring.
clear-lens extraction group compared
Augusto Azuara-Blanco and colleagues with the laser iridotomy group was the The study had several limitations. At
have published a prospective reason for the better patient-reported three year follow up, nearly 50% of
randomized study comparing laser outcome. The IOP difference between pf patients did not have gonioscopy
iridotomy with clear-lens extraction groups was 1·18 mm Hg. This difference findings recorded. In an angle closure
as the initial treatment of primary is not clinically relevant, and we should glaucoma study, this lack of gonioscopy
angle closure and primary angle- also remember that the study excluded findings is one of the significant
closure glaucoma.[18] This is the first all patients with advanced glaucoma limitations. We have no exact
large scale RCT dealing with role of damage. However, the clear-lens information about what happens to
angle, especially in the Laser PI group,
34 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
wherein the presence of lens, angle still controlled trials (RCT) and clinical was not clear. As appositional closure
could have narrowed significantly, and controlled trials (CCT). [19] A total of 5 RCT is likely to behave differently with lens
the degree of PAS could have increased. and 11 CCT involving 1495 eyes were extraction from permanent synechial
The study did not look into lens vault included. The results of meta-analysis closure this makes extrapolation a
or lens volume parameters and both showed that phacotrab+IOL group was little difficult. IOP decreases of 1.5
parameters do play important role in superior than trabeculectomy group) mmHg, which might be considered
deciding early cataract surgery in PACD (MD -3.93,95%CI [-7.31, -0.54]) which clinically significant, seem to have
patient. was also superior than phaco+IOL been discounted because statistical
group (MD 0.52,95%CI [0.10, 0.95]) in significance was not achieved.
Our remarks: decreasing IOP. Phacotrab group (MD- The companion RCT for medically
1.45,95%CI [-1.68, -1.22]) and phaco controlled PACG yielded similar
We had few small prospective and lots group (MD-1.12,95% CI [-1.87, -0.37]) results. In medically controlled PACG,
of retrospective studies assessing the are both deeper than trab group in the the phacotrabeculectomy group did
role of clear lens extraction in PACG. anterior chamber depth. In increasing not have any clinically significant IOP
This study showed that clear lens/ the coefficient of outflow facility of decrease beyond 9–15 months. Intra-
early cataract surgery do have merit in aqueous humor (C values) there was operative complications occurred at the
selected patients. However, the authors no statistical difference in the three same rate with the two operations, and
had not included lens parameters in groups. And there was no statistical are essentially related to the cataract
study, so we could not get any specific difference between phacotrab groups surgery, suggesting that combination
answers regarding which group of and phaco groups in visual acuity but surgery does not amplify the difficulty
patients based on ocular biometry and phacotrab group was superior than or likelihood of complications from
lens parameters would benefit the most. phaco group (MD 1.07, 95%CI [0.73, the cataract surgery. Postoperative
1.40]) in the use of IOP-lowering drugs. complications, on the contrary, were
Phacoemulsification to treat primary There was no statistical difference significantly higher in the combined
angle closure can be technically among three groups. They concluded surgery group, but are entirely related
challenging, more so in eyes with acute that phacotrab+ IOL group was superior to the trabeculectomy surgery, and do
attack just few days before cataract than trab group which was also superior not compare unfavourably to quoted
surgery. The surgeons involved in than phaco+IOL group in decreasing rates of complications in stand-alone
both studies were highly experienced. IOP. Phacotrab group and phaco group trabeculectomy surgery reported
Training for routine cataract surgery increased the ACD more than Trab elsewhere. The above trials demonstrate
might not provide the skills needed group. Phacotrab group required less that cataract extraction alone may be
to reach consistently excellent results number of IOP-lowering drugs. useful in cases of medically controlled
for phacoemulsification in clear-lens PACG in which there is some degree of
extraction in primary angle closure cases Tham et al. separately published appositional closure that can be opened.
that would achieve the safety margin combined complications of the In the medically uncontrolled group, the
and avoid the few but potentially severe RCTs involving Trabeculectomy, addition of a trabeculectomy to cataract
intraoperative complications, and less phaco-trabeculectomy versus only extraction may provide a small but
experienced surgeons might incur more phacoemulcification.[20] In the clinically significant IOP reduction. The
difficulties and complications. phacoemulsification group, 5 of the addition of a trabeculectomy may not be
62 CACG eyes (5 events, 8.1%) and 16 needed for medically controlled PACG
Role of Phacoemulsification 0f 61 CACG eyes (19 events, 26.2%) provided that a greater requirement for
versus Trabeculectomty or in combined phaco-trabeculectomy glaucoma medications is acceptable.
combine Phacoemulsification group, had surgical complications. 16 We feel that these results can be safely
& Trabeculectomy versus of the 61. This data converts into NNH extrapolated to CLE but with a higher
Phacoemulsification in PACG: (Number Needed to Harm) of 5.5; that risk-to-benefit ratio. This extrapolation
means for every nearly six glaucoma does not, however, provide an ipso
Deng BL et al evaluated the efficacy surgery (either trabeculectomy/ phaco- facto endorsement of CLE as the
and safety of trabeculectomy, trabeculectomy), we get one more preferred surgical therapy in PACG. In
phacotrabeculectomy plus intraocular complication, however it the BCVA the case of medically controlled PACG
lens implantation (phacotrab+IOL were similar in both groups. there is – in the absence of cataract –
group) and phacoemulsification with little indication for surgery except to
IOL Our Remarks: decrease the burden of medications.
In the medically uncontrolled group,
(phaco+IOL) in primary angle-closure The number of patients with depending on the target IOP it may be
glaucoma (PACG) in a systematic appositional versus synechial closure as argued that the preferred procedure
review and meta-analysis of randomized well as the extent of PAS in each group
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Subspeciality-Glaucoma
remains trabeculectomy alone. The data from trials addressing cataract References
question is whether the IOP lowering extraction in PACD and estimates
from lens extraction alone will be of the rate of the events we hope to 1. Quigley HA, Broman AT. The number
sufficient to achieve target IOP, and prevent with lens extraction to provide of people with glaucoma worldwide in
whether the optic disc can withstand guidelines for the use of CLE. In APAC, 2010 and 2020. Br J Ophthalmol 2006;
the IOP spike commonly seen once the attack has been aborted, clear 90:262–267.
following lens extraction in PACD. lens extraction can be considered
Trabeculectomy may still be required when conventional treatment does not 2. Thomas R, Sekhar GC, Kumar RS.
as a second procedure – particularly stabilize the eye following an acute Glaucoma management in developing
in medically uncontrolled angle attack. Acute intervention with lens countries: medical, laser, and surgical
closure glaucoma – and the prolonged extraction as primary treatment in options for glaucoma management in
presence of postoperative flare after APAC remains less appealing except countries with limited resources. Curr
routine cataract surgery would suggest in resistant cases due to potential for Opin Ophthalmol 2004; 15:127–131.
that ideal surgical conditions for a surgical complications that can be
trabeculectomy might not then be avoided by conventional treatment 3. Thomas R, Sekhar GC, Parikh R. Primary
present again until at least 6 months and an elective approach to the lens angle closure glaucoma: a developing
later. Primary angle closure A total of if later indicated. The role of CLE in world perspective. Clin Exp Ophthalmol
28.5% of PAC are expected to progress fellow eyes is best restricted to those 2007; 35:374–378.
to PACG over 5 years. The rate of who continue to have symptoms, or
APAC in PAC can be estimated from a recurrent attack despite the use of 4. Lowe RF. Aetiology of the anatomical
published incidence data to be between laser iridotomy, laser iridoplasty as basis for primary angle closure
0.4 and 3% per year (above 60 years of well as medications. In PACS, there is glaucoma. Br J Ophthalmol 1970;
age). These risks of APAC and PACG are currently no role for CLE. 54:161–169.
initially best addressed conventionally
with treatment including LPI, and For PAC, clear lens extraction is only 5. Tarongoy P, Ho CL, Walton DS. Angle-
further laser and medical treatment considered if conventional treatment closure glaucoma: the role of the
for any residual elevation of IOP. It (LPI, iridoplasty and medications) does lens in the pathogenesis, prevention
is reported, however, that 20–59% of not control the IOP and a significant and treatment. Surv Ophthalmol
eyes may not open fully after an LPI, portion of the angle can be opened on 2009;54:211–225.
and that PAS may continue to progress. indentation gonioscopy. There are no
Lens extraction alone may lead to data to support combining CLE with 6. Hayashi K, Hayashi H, Nakao F, Hayashi
more successful IOP control than LPI, goniosynechialysis. F. Changes in anterior chamber width
particularly in eyes in which the PAC is and depth after intraocular lens
defined by elevation in IOP rather than Medically controlled PACG without implantation in eyes with glaucoma.
the presence of PAS. The results of the cataract does not require intervention. Ophthalmology 2000; 107:698–703.
RCT for medically controlled PACG can CLE is considered in uncontrolled
be extrapolated to cases of PAC with PACG despite conventional laser 7. Kurimoto Y, Park M, Sakaue H, Kondo
gonioscopic findings similar to trial and medical treatment especially if T. Changes in the anterior chamber
participants; CLE can be expected to ‘significant’ angle opening is possible configuration after small incision
have similar IOP-lowering effects but on indentation gonioscopy. A decision cataract surgery and intraocular lens
with a higher risk to-benefit ratio. Lens is still required in PACG as to whether implantation. Am J Ophthalmol 1997;
extraction is expected to relieve angle lens extraction should be combined 124:775–780.
crowding; however, such an effect is not with trabeculectomy or whether
invariable; in a small series of cases, it trabeculectomy alone is preferred. 8. Nonaka A, Kondo T, Kikuchi M, et al.
was suggested that lens extraction may Angle widening and alteration of ciliary
be ineffective in treating plateau iris There are currently only one process configuration after cataract
configuration. randomized controlled trials supporting surgery for primary angle closure.
the use of CLE as treatment for PACG. Ophthalmology 2006;113:437–441.
Conclusion A benefit from the procedure is
biologically plausible and extrapolation 9. GunningFP,GreveEL.Lensextractionfor
Earlier removal of cataracts seems to be from existing randomized trials uncontrolled angle-closure glaucoma:
a reasonable option in PACD, but at the to a few specific situations may be long-term follow-up. J Cataract Refract
present time there is no published data possible. Any potential benefit must be Surg 1998; 24:1347–1356.
to guide the use of clear lens extraction carefully weighed against the risks of
for this condition. We have combined intervention. 10. Roberts TV, Francis IC, Lertusumitkal
S, et al. Primary phacoemulsification
for uncontrolled primary angle closure
glaucoma. J Cataract Refract Surg
2000;26:1012–1016.
11. Jacobi PC, Dietlein TS, Lu¨ ke C, et al.
Primary phacoemulsification and
intraocular lens implantation for acute
angle-closure glaucoma. Ophthalmology
2002; 109:1597–1603.
12. Friedman DS, Vedula SS. Lens extraction
36 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
for chronic angle-closure glaucoma. a review. Clin Exp Ophthalmol 2010; 38 Xu-Dong Jiu, Le-Xin Yang, Jing Tian.
Cochrane Database Syst Rev 2006; DOI: 10.1111/j.1442-9071.2010.02374.x. Surgical treatment for primary angle
3:CD005555. The removal of visually significant closure-glaucoma: a Meta analysis. Int J
cataract may be beneficial in some PACD Ophthalmol. 2011;4:223-7.
13. Lam DS, Leung DY, Tham CC, but there is no evidence for efficacy of 20. Tham CCY, Kwong YYY, Leung
et al. Randomized trial of early clear lens extraction in this condition. DYL, et al. Phacoemulsification vs.
phacoemulsification versus peripheral phacotrabeculectomy in chronic
iridotomy to prevent intraocular 17. Husain R, Gazzard G, Aung T, Chen angle closure glaucoma with cataract:
pressure rise after acute primary Y, Padmanabhan V, Oen FT, Seah SK, complications. Arch Ophthalmol 2010;
angle closure. Ophthalmology 2008; Hoh ST. Initial management of acute 128:303–311.
115:1134–1140. primary angle closure: a randomized
trial comparing phacoemulsification Corresponding Author:
14. Tham CC, Kwong YY, Leung DY, et al. with laser peripheral iridotomy.
Phacoemulsification versus combined Ophthalmology. 2012;119:2274-81. Dr. Rajul Parikh
phacotrabeculectomy in medically Shreeji Eye Clinic & Palak’s Glaucoma Care
controlled chronic angle closure 18. Azuara-Blanco A, Burr J, Ramsay C, centre, Samrat Bldg, Andheri (E),
glaucoma with cataract. Ophthalmology Cooper D, Foster PJ, Friedman DS, Mumbai, India
2008; 115:2167–2173. Scotland G, Javanbakht M, Cochrane
C, Norrie J; EAGLE study group.
15. Tham CC, Kwong YY, Leung DY, Effectiveness of early lens extraction for
et al. Phacoemulsification versus the treatment of primary angle-closure
combined phacotrabeculectomy in glaucoma (EAGLE): a randomised
medically uncontrolled chronic angle controlled trial. Lancet. 2016 Oct
closure glaucoma with cataracts. 1;388(10052):1389-1397
Ophthalmology 2009; 116:725–731.
19. Bo-Lin Deng , Cheng Jiang, Bin Ma, Wen-
16. Walland M, Thomas R. Role of clear lens Fang Zhang, Peng Lü, Yuan-Yuan Du,
extraction in adult angle closure disease:
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Subspeciality-Glaucoma
Burden of Glaucoma in India
Jatinder Singh Bhalla (MS, DNB, MNAMS), Prathama Sarkar (MS, DNB)
Department of Ophthalmology , DDU Hospital, New Delhi
Introduction 64.3 million worldwide. According glaucoma which caused 12.8% of the
Glaucoma is the second leading cause to Glaucoma Society of India, the blindness in the country1. This was
of blindness in the world. The number prevalence of glaucoma in India is expected to increase up to 76 million in
of people suffering from glaucoma between 2% to 13%. By the year 2000, 2020 and 111.8 million in 20402.
in the year 2013 was estimated to be 12 million Indians were affected with
Table 1: Methodology of population-based studies on glaucoma from Central and North India
Study name Year Type of Study No. of Age Area
Glaucoma Survey – 20019 2001 Community-based subjects 35 years and above
cross-sectional survey 7438 Rajnandangaon
Hoogly River Glaucoma 40 years and above district of
Study10 2011- 2014 Population-based cross- 14092 Chhattisgarh state
sectional study Kolkata
An Epidemiological Study 2013 Cross-sectional Study 24651 50 years and above Delhi
of Glaucoma in a Semi-
urban Population of Delhi11
A community-based study 2015- 2016 Community-based 680 40 years and above Aligarh
of scenario of glaucoma in cross-sectional study
Aligarh12
Prevalence of glaucoma in 2015-16 Cross-sectional Study 17792 All ages Jagdalpur
rural India13
Epidemiological studies in Eye Disease Study [APEDS]4, Aravind Study [WBGS])8 India. Only a few cross-
India Comprehensive Eye Survey [ACES]5, sectional studies have been done in
and the Chennai Glaucoma Study Northern India (shown in table 1 and
Various large-scale studies have been [CGS])6 have been conducted in the 2). Though various modern techniques
conducted to provide an insight about southern part of India and some have are available for diagnosing glaucoma,
the ongoing situation of glaucoma in been carried out later in central (Central yet the prevalence of primary open-
India. Most of these studies (Vellore India Eye and Medical Study [CIEMS])7 angle glaucoma (POAG), primary
Eye Study [VES]3, Andhra Pradesh and eastern (West Bengal Glaucoma angle-closure glaucoma (PACG),
38 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
and exfoliation glaucoma varied important information15. POAG was was consistently a risk factor in these
considerably, which was attributed shown to be more common than studies, and changing demographics
to the definitions used to characterize PACD. About 90% of POAG in the and senescence will significantly
these forms of the disease14. population was undetected, and both increase the burden of glaucoma in this
POAG and PACD were more common country
All of these major studies provided in urban than rural cohorts. Aging
Table 2: Summary of cross- sectional studies on glaucoma in India
Name of Study Important Findings
Glaucoma Survey – 20019 The age-sex standardized prevalence of glaucoma was 3.68%.
Gender variation of glaucoma was not significant.
Incidence of open angle, closed angle, secondary glaucoma, ocular hypertension and glaucoma
suspects was 13.1%, 21.2%, 21.2%, 14.5% and 30% respectively.
Twenty-five per cent of the glaucoma cases were detected for the first time during the survey.
Hoogly River Glaucoma 2.7% were detected to have glaucoma in rural arm and 3.23% in urban arm (P < 0.001).
Study10
In urban population, 2.10% had POAG, 0.97% had PACG, and 0.15% had secondary glaucoma.
In rural population, 1.45% had POAG, 1.15% had ACG, and 0.10% had secondary glaucoma.
An Epidemiological 43 were angle closure glaucoma and 218 were open angle glaucoma.
Study of Glaucoma in a
Semi- urban Population of
Delhi11
Newer cases diagnosed were 118(78 of open angle glaucoma and 30 of angle closure glaucoma).
Overall prevalence of glaucoma was 10.59 cases per 1000 population.
The overall male to female distribution was 121 male cases to 140 female cases but this figure
was skewed towards 30 females to 13 males in case of angle closure.
Gender variation of glaucoma was not significant.
A community-based study IOP of the majority of population lied in 11-15 mm Hg with a mean IOP of 13.42±4.09 mmHg.
of scenario of glaucoma in
Aligarh12
A cup to disc ratio of >0.6 was found in 35 eyes.
The overall prevalence of glaucoma was found to be 4.6% (31/680).
Prevalence of glaucoma in Prevalence of primary open angle glaucoma, primary angle closure glaucoma, normotensive
rural India13 glaucoma and secondary glaucoma as 1.3%, 1.2%, 1.2% and 0.9% respectively.
Overall prevalence of primary open angle glaucoma was 0.26%, 0.06% for normal tension
glaucoma, 0.06% for angle closure glaucoma and 0.03% for juvenile glaucoma.
The prevalence of common type of secondary glaucoma was 0.15% for lens induced glaucoma,
0.06% for traumatic and 0.05% for aphakic glaucoma.
Primary open angle glaucoma was more common with maximum number of cases in the age
group of 56-75 years, average age being 61 years.
High prevalence rate of glaucoma was due to poor health education, low socioeconomic status
and inaccessibility of ophthalmologists specifically in rural and tribal areas.
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Subspeciality-Glaucoma
Diagnostic Criteria completely on intraocular pressure disc) or functional (visual field) damage
Various studies have used various for glaucoma diagnosis except when to diagnose glaucoma. The Chennai
diagnostic criteria for the purpose visual field or optic disc data is not Glaucoma Study6 (CGS) and the West
of defining glaucoma. All studies available. This is in accordance with the Bengal Glaucoma Study8 (WBGS) used
have brought forward the optic disc International Society for Geographical the ISGEO guidelines for diagnosing
changes criteria to diagnose glaucoma. and Epidemiological Ophthalmology glaucoma in population-based studies.
Most of the studies have not relied (ISGEO) emphasis on structural (optic (Table 3)
Table 3: Major population-based studies in India on prevalence of glaucoma
Study name Age Year when conducted No. of subjects
The Vellore Eye Study (VES)3 30-60 years
1994 972
Andhra Pradesh Eye Disease Study 40 years and above 1996 - 2000 934 - urban + 2790 - rural
(APEDS)4 40 years and above 1995 -1997 5150
Aravind Comprehensive Eye Survey 50 years and above 1998 -1999 1594
(ACES)5
West Bengal Glaucoma Study (WBGS)8
Chennai Glaucoma Study (CGS) 6 40 years and above 2001- 2004 3850 rural + 3934 urban
Central India Eye and Medical Study 30 years and above 2006 - 2008 4711
(CIEMS)7
Types of glaucoma With the exception of the VES3 the normal intraocular pressure. Again,
reported prevalence rates for POAG this is one of the causes leading to a
Ocular hypertension appeared to be higher in urban significant proportion of undiagnosed
population [CGS(Urban)6 and APEDS4]. illness - a single regular IOP would not
VES3, APEDS4 and ACES5 have reported In WBGS8, 9 of every 10 glaucoma rule out disease. Therefore, a proper
different rate of incidence of OHT. The cases were classified as POAG. Lifestyle optic disc evaluation is necessary for
APEDS4 recorded the lowest prevalence changes and their related cardio- all the cases.
of 0.42%. There were 1.1% individuals vascular influences may account in
with OHT for those aged 40 years and part of this increase in prevalence may The increase in the age was the
over in ACES5. The VES3 indicated that be the prime reason behind this. consistent risk factor for all studies.
3.08% were ocular hypertensive. 4.22 Males were at greater risk of POAG in
percent of those with PXF in the ACES5 CIEMS7 showed a ratio of open-angle the ACES5. The prevalence of definite
and 9.33% of those with PXF in the glaucoma to angle-closure glaucoma glaucoma among males and females
CGS6 (Rural) were ocular hypertensive, of 108/14 or 7.7:1, which was higher combined increased from 2.7% (95%
and pseudoexfoliation was generally than what seen in VES3 and APEDS4. CI 1.7 to 3.7) in people aged 50–59
linked with ocular hypertension. The prevalence of 3.45% of glaucoma years to 6.5% (95% CI 0.0 to 14.1) in
However, WBGS8 didn’t take into in the study population aged 40+ years those aged 80 years or more in WBGS8.
account OHT. was similar to the studies conducted in No significant gender difference was
south India. reported by any of the other studies.
Primary open angle glaucoma Myopia was also a risk factor for POAG
The proportion of individuals with in the ACES5 and CIEMS7.
The lowest rate of 0.41% was recorded POAG who exhibited a “normal” IOP
by the VES3. The VES3 reported (defined as two standard deviations Angle closure disease
prevalence is not dissimilar when above the population mean) was
contrasting the prevalence of POAG substantial in all prevalence studies. The disparities in reported prevalence
in the 30-60 age group with APEDS4 Sixty-five percent of those with POAG of angle closure disease are perhaps
(1.01%). The possible explanation is in APEDS4, 45% in ACES5, 67% in CGS6 most representative of the influence
the poor output rate of the visual field (rural) and 82% in CGS6 (urban) had of the different methodology and
in the VES3.
40 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
diagnostic criteria used by these Pseudoexfoliation glaucoma Conclusion
studies.
It is one of the risk factors for glaucoma Glaucoma is the second leading cause
The VES3 was the first to report and its prevalence in clinic-based of blindness in the world, accounting
that PACG comprised a significant studies from India has been variously for up to 8% of overall blindness. More
proportion of those with glaucoma. A reported to be between 1.87 and than 90% of glaucoma patients remain
number of persons were also reported 13.5%. The prevalence of glaucoma undiagnosed in the population. There
to have occludable angles (equivalent among those with pseudoexfoliation is a lack of epidemiological and risk
to PACS). Five persons (0.51%) were was reported to be 3.02% in the factor data on glaucoma, and more of
reported to have angle closure disease APEDS4, 7.5% in ACES5 and 13% in these studies with a broader patient
with disc and field damage. These the rural cohort of the CGS6. The base and longer term are needed to
would correspond to a diagnosis of risk of pseudoexfoliation increased determine the prevalence of glaucoma.
PACG. The urban area of the CGS6 with increasing age with no gender Initiatives are required for increasing
had higher rates of PAC, PACS and predilection. Those predominantly public awareness and comprehensive
PACG than the rural cohort, though involved in outdoor activities were eye examinations by ophthalmologists
overall prevalence rate was similar at greater risk of PXF than those to decrease or eliminate undiagnosed
to VES3. The prevalence of angle- whose occupation was classified as glaucoma.
closure glaucoma was 0.88% (95%CI: indoor. The WBGS8 reported only two
0.60, 1.16) in the CIEMS7. Subsequent suspects of secondary glaucoma with Refrerences
reports from the APEDS4 did report pseudoexfoliation.
a lower prevalence of angle closure 1. Dandona R, Dandona L. Review of
disease. The difference was most Secondary glaucoma findings of the Andhra Pradesh Eye
marked in the lower prevalence of Disease Study: policy implications for
PACS. This can partly be explained by The rates of secondary glaucoma eye care services. Indian J Ophthalmol
a stricter criterion for occludability have been reported by some studies. 2001; 49:215-34.
(non-visibility of the pigmented The WBGS8 reported a rate of 0.08%,
trabecular meshwork in 270° or more APEDS4: 0.21% in those aged of 30 and 2. Quigley HA, Broman AT. The number
of the filtering angle). above 3 and 0.3% in the ACES5. of people with glaucoma worldwide
in 2010 and 2020. Br J Ophthalmol
However, the WBGS8 found only three The report from the CGS6 highlighting 2006;90(3):262- 7.
people with PACG out of 1324 screened the high rates of glaucoma (11.2% of
with a crude prevalence of 0.23% in the aphakes/pseudophakes examined) 3. Jacob A, Thomas R, Koshi SP, et al.
people aged 50 years. They stated that among those who had undergone Prevalence of primary glaucoma in an
PACG may be less prevalent in Bengalis cataract surgery directs attention urban south Indian population. Indian
than in Indian populations living towards a large at-risk population in J Ophthalmol. 1998; 46:81-86.
further south in the subcontinent. India. Those who have undergone
Hence, PACG, therefore, did not seem cataract surgery are in the same age 4. Garudadri C, Senthil S, Khanna RC, et al.
to be a major public health problem cohort at risk for glaucoma. Prevalence and risk factors for primary
among rural Bengalis according to this glaucomas in adult urban and rural
study. Blindness and glaucoma populations in the Andhra Pradesh
Eye Disease Study. Ophthalmology.
Increasing age was a common risk Glaucoma is the second leading cause 2010;117: 1352-1359.
factor for PACG in all studies3-8. Female of blindness in the adult population
gender (CGS)6 was a risk factor for in India. The proportion of those 5. Ramakrishnan R, Nirmalan PK,
PACG and PAC. Hyperopia was also a diagnosed to be bilaterally blind Krishnadas R, et al. Glaucoma in a
risk factor in the Chennai glaucoma because of POAG in the APEDS4, ACES5, rural population of southern India: the
a study (Urban), a trend of increased CGS (rural), CGS6 (Urban), WBGS8 and Aravind comprehensive eye survey.
risk with hyperopia was noted both CIEMS7 were 11.1%, 1.6%, 3.2%, 1.5%, Ophthalmology. 2003;110:1484-1490.
in APEDS4 and CGS6 (Rural). Eyes 5.2% and 10.5% respectively. The
with angle closure disease had been corresponding figures for PACG for 6. Vijaya L, George R, Baskaran M, et
reported to have shorter axial length APEDS4, CGS6 (rural), CGS6 (Urban), al. Prevalence of primary open-angle
and a shallower anterior chamber and WBGS8 and CIEMS7 were 16.6%, glaucoma in an urban south Indian
thicker lenses than normals by the 2.9%, 5.9% and 0%. However, 19% population and comparison with a rural
CGS6. were found to be unilaterally blind in population. The Chennai Glaucoma
CIEMS7. Study. Ophthalmology. 2008; 115:648-
654.
7. Nangia V, Jonas JB, Matin A, et al.
Prevalence and associated factors of
glaucoma in rural central India. The
Central India Eye and Medical Study.
PLoS One. 2013;8:e76434.
8. Raychaudhuri A, Lahiri SK,
www.dosonline.org/dos-times DOS Times - Volume 26, Number 4, January-February 2021 41
Subspeciality-Glaucoma
Bandyopadhyay M, et al. A population Rajshekhar. An Epidemiological Study 15. Ronnie G, Ve RS, Velumuri L, et al.
based survey of the prevalence and (Cross-sectional Study) of Glaucoma Importance of population-based
types of glaucoma in rural West in a Semiurban Population of Delhi. studies in clinical practice. Indian J
Bengal: the West Bengal Glaucoma Journal of Clinical & Experimental Ophthalmol.
Study. Br J Ophthalmol. 2005; 89:1559- Ophthalmology. 2017; 08:5.
1564. Corresponding Author:
12. Ahmad, Syed & Ahmad, Anees &
9. Palimkar A, Khandekar R, Khalique, Najam & Alvi, Yasir. A Dr. Jatinder Singh Bhalla, MS, DNB, MNAMS
Venkataraman V. Prevalence and community based study of scenario Consultant & Head, Department of
distribution of glaucoma in central of glaucoma in Aligarh, India. Ophthalmology ,
India (Glaucoma Survey 2001). Indian J International Journal Of Community DDU Hospital, Hari Nagar, New Delhi, India.
Ophthalmol. 2008 Jan-Feb;56(1):57-62. Medicine And Public Health.2019; 6.
4098-4104.
10. Paul C, Sengupta S, Choudhury S,
Banerjee S, Sleath BL. Prevalence 13. https://www.ipinnovative.com/media/
of glaucoma in Eastern India: The journals/PJMS_6(3)_125-127.pdf (Last
Hooghly River Glaucoma Study. Indian ssessed on 23-11-2020; 15:19)
J Ophthalmol. 2016 Aug;64(8):578-83.
14. George R, Ve RS, Vijaya L. Glaucoma
11. Singh, Shilpa & Chakarvarty, Sunil in India: estimated burden of disease. J
& Narula, Anurag & Vemparala, Glaucoma. 2010; 19:391-397.
42 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
Clinical Pearls for Glaucoma
Management in some Special
Situations
Jatinder Singh Bhalla, Kanika Jain, Ashwini Kulkarni,
Satender Singh, Rakesh Verma, Amit Mehtani
Department of Ophthalmology , Deen Dayal Upadhyay Hospital, New Delhi
Introduction medicolegal constraints, limited yy As the greatest risk to the developing
Glaucoma is an irreversible, progressive sample size, and low financial fetus is in the first trimester,
optic neuropathy. In clinical practice, incentives to drug companies discontinuation of medications
multiple modalities are used to come evaluating products in these should occur prior to conception
to a diagnosis of glaucoma. The populations categories. Evidence and through the first trimester.
presentation of glaucoma can be varied of glaucoma medication safety is
from primary glaucoma to secondary pregnancy is largely derived from yy If the patient has early glaucoma
glaucoma based on the clinical case reports and animal studies. or is only a suspect, stopping
presentation in these patients. The age medications for a number of
group to be affected can range from yy There are no glaucoma medications months should not pose any great
childhood to adults. The management that fall into category A. risk to vision. Intraocular pressure
of glaucoma is also multimodal and can (IOP) tends to decrease during
be managed medically, surgically, laser yy Brimonidine is a category B drug, pregnancy in healthy patients,
intervention, cyclodestructive therapy. but it has been shown to cross the especially during the second and
The management also depends upon placenta and could potentially third trimesters.
the diagnosis of glaucoma. This short cause apnea in neonates if used
review article will focus on pearls of through parturition. yy If a woman has advanced glaucoma
management of glaucoma in various and elevated IOP or if she is on
challenging and special situations yy Beta blockers, Carbonic Anhydrase polytherapy, serious consideration
which can be encountered in our Inhibitors (CAIs), prostaglandin should be given to surgery before
clinical practice. The discussion of analogs,andparasympathomimetics conception.
management of primary open angle are classified as category C.
glaucoma, primary angle closure yy If pregnancy is established and
glaucoma, normal tension glaucoma yy Systemic Acetazolamide has treatment is necessary, laser
and ocular hypertension is out of the teratogenic effects. trabeculoplasty (LTP) is probably
scope of this review article. the best initial therapy and a good
yy Prostaglandins are known to alternative to medication.
Glaucoma Management in stimulate uterine contraction and
Pregnancy (Table 1) may cross the blood–placental yy If medications cannot be stopped
yy The management is controversial barrier; prostaglandin analogs then the use of beta blockers,
should be avoided during pregnancy cholinergics, topical CAIs, and
and challenging to minimize risk of premature labor. alpha agonists can be continued.
yy Trials to establish “safety and However, beta blockers and alpha
yy Childbearing plans should be agonists should be discontinued
efficacy” of ophthalmic solutions addressed with all women of after the 8th month of pregnancy, to
are seldom performed in children reproductive age who have avoid beta- or alpha-blockade in the
or pregnant women because of glaucoma. The risks and benefits neonate.
of glaucoma treatment to the fetus
versus vision loss in the mother
must be discussed.
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Subspeciality-Glaucoma
Table 1: Risk category of drugs during pregnancy
Risk category of drugs during pregnancy
Category Antiglaucoma Examples of antiglaucoma medications
A Adequate studies in pregnant women have failed to demonstrate None
a risk to the foetus
B Adequate human studies are lacking, but animal studies have Brimonidine
failed to demonstrate a risk to the foetus OR
Adequate studies in pregnant women have failed to demonstrate a
risk to the foetus, but animal studies have shown an adverse effect
on the foetus
C Adequate studies in pregnant women and animals are lacking or Beta blockers, Carbonic anhydrase
have shown an adverse effect on foetus, but potential benefit may inhibitors, prostaglandin analogs,
warrant use of the drug in pregnant women despite potential risk parasympathomimetics
D There is evidence of human foetal risk, but the potential benefits
from use of the drug may be acceptable despite the potential risk
X Studies in animals or humans have demonstrated foetal Acetazolamide
abnormalities and potential risk clearly outweighs possible benefit
yy Filtering surgery can be considered obstetrician and may depend on the Figure 1: Buphthalmos in a child with
if glaucoma is progressive and an stage of the glaucoma. bilateral congenital glaucoma
adequate IOP cannot be obtained
with LTP or with the medications Glaucoma Management in (EUA) is required to diagnose
mentioned above. Lactating Mothers childhood glaucoma and to plan
yy Risks of medication to the infant appropriate management
yy It is desirable to defer surgery until yy Once a child has been diagnosed with
the second trimester of pregnancy must be weighed against the risks of glaucoma, the goal, where possible,
to reduce the fetus’ exposure to not using medications to the mother. is to provide a lifetime of vision.
potentially teratogenic anesthetic yy Beta blockers are concentrated in yy During EUA, anesthetic agents,
agents. breast milk and should be avoided. speculums, and mode of airway
yy Alpha agonists should be avoided securement can all affect the IOP
yy The patient should be positioned since their excretion into human reading; the IOP measured as soon as
with the uterus displaced laterally breast milk is unknown. Systemic possible following induction, is best.
so as to avoid aortic and vena caval CAIs should be used with caution or yy Surgery is the mainstay of treatment
compression by the gravid uterus. avoided all together to be safe. and is often inevitable in a child’s
yy Topical CAIs, prostaglandins, and lifetime. Pediatric glaucoma
yy Antimetabolites, such as 5-FU or miotics are reasonable choices surgery poses a challenge for every
Mitomycin C, should not be used on during lactation. ophthalmologist because of its
a pregnant woman for medicolegal yy If surgery is planned, breast milk atypical presentation, distorted
reasons. should be stored in order to have anatomy due to buphthalmos,
milk unaffected by anesthetic agents. compromised corneal clarity and
yy Postoperatively, topical steroids exuberant fibrotic response to
using punctal occlusion are safe. Glaucoma Management in
Childhood Glaucomas
yy Diode laser cyclodestruction can be yy Managing glaucoma in childhood is
a valuable alternative to filtering
surgery one of the greatest challenges in the
field of glaucoma.
yy Mode of delivery- esp. vaginal yy Thorough clinical evaluation via
delivery- risks of vision loss from examination under anaesthesia
elevated eye pressure and decreased
blood flow to the optic nerve during
the pushing phase of labor should be
discussed with the mother as well as
44 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
surgery. Many of them may need a strongly with the development of Figure 4: Homogeneous band of trabecular
second surgery at later stages. PXF glaucoma than does the amount hyperpigmentation seen in PDS
yy Medical therapy usually provides of PXF material.
a supportive role to reduce the IOP yy Pseudoexfoliation (PXF) eyes have yy PDG patients have higher IOP
temporarily, to clear the cornea, and an increased risk of complications peaks and greater IOP fluctuation
to facilitate surgical intervention associated with cataract surgery even with strict adherence to the
yy There are compliance, cost issues and due to poor pupil dilation and poor treatment than POAG patients. Rate
systemic effects of drugs in children zonular integrity. of progression is unpredictable.
along with poor, unpredictable yy Cataract extraction should be
response to medications considered at earlier stages in PXF yy Pigment Dispersion Syndrome
yy B blockers is the first line of treatment eyes because less zonular stress is (PDS) patients have a 10% risk of
yy Pilocarpine and Carbonic Anhydrase induced by the removal of softer converting to PDG at 5 years and
Inhibitors are considered second line nuclei. 15% risk at 15 years.
of treatment yy Using a CTR or a three-piece IOL may
yy Children are considered to be non- be helpful in redistributing zonular yy Most medication classes can be used
responsive to Prostaglandin Analogs stress to minimize additional zonular in PDG patients and an IOP reduction
in most of cases. loss. (Figure 3) similar to that seen in POAG patients
yy Alpha agonists are contraindicated yy PXF eyes have more postoperative is expected. Care should be taken
in children in view of respiratory inflammation that may require while using cholinergic agents
and CNS depression. a more prolonged course of anti- in these patients because of their
inflammatory treatment. increased risk of retinal detachment/
Glaucoma Management in yy Glaucoma management remains acute increase in pigment release.
Pseudoexfoliation Glaucoma same as in the primary open
yy The presentation of clinically angle glaucoma although rate of yy Peripheral iridotomy (PI) decreases
progression is unpredictable and fast. the biomechanical factor causing
apparent pseudoexfoliation (PXF) Response to medical management contact between the iris and
material is often unilateral which is disappointing and surgical zonular fibers and may lower IOP
often becomes bilateral with long intervention including filtering over the long-term by relieving the
term observation. surgery or valves has to be resorted reverse pupillary block (as seen on
yy The presence of PXF material in to. Ultrasound biomicroscopy- Figure
the eye is a significant risk factor 5). Nevertheless, the effects of PI on
for ocular hypertension and the
development of PXF glaucoma
(Figure 2). Thus, patients with PXF
material in the eye should be closely
monitored for the development of
glaucoma.
yy The degree of iridocorneal angle
pigmentation correlates more
Figure 2: Characteristic deposits of Figure 3: Capsular Tension Ring can Figure 5: Pigment dispersion syndrome
pseudoexfoliative material on the anterior facilitate in combating zonular instability in on Ultrasound biomicroscopy (UBM):
lens capsule in a ring like manner patients with pseudo-exfoliation glaucoma/ Posterior bowing of the iris (down arrow)
syndrome causing touch between iris and zonules,
causing pigment dispersion
Glaucoma Mangement in
Pigment Dispersion Glaucoma
yy The amount of pigment in the angle
observed at the slit lamp does not
correlate to the risk of converting
to Pigment Dispersion Glaucoma
(PDG) (Figure 4)
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Subspeciality-Glaucoma
visual field changes or progression Figure 7: Angle Recession seen on gonioscopy not avoid prostaglandin analogues
have not been established in PG and in a patient who sustained blunt trauma unless patients have a history of
PDS. There is no scientific evidence or active cystoid macular edema,
as of yet to advocate PI as a treatment yy Approximately 9% of patients with aphakia or herpetic eye disease.
for PDS or PG. angle recession will go on to develop However, prostaglandin analogues
yy Selective laser trabeculoplasty (SLT) glaucoma. Greater than 180° of angle are not first line agents in uveitic
has been shown to be an effective recession makes it more likely that glaucoma.
procedure with higher success rates ARG will develop. yy Pupillary block due to inflammation
in PDG patients than in other types causing iris bombe formation
of open angle glaucoma. (Figure 6) yy Complete ocular evaluation, requires urgent, multiple, adequate
Since the increased pigmentation including gonioscopy, is mandatory sized peripheral iridotomies with
of the trabecular meshwork allows in patients with blunt ocular trauma, increased frequency of instillation
greater absorption of energy, it is even if it occurred in the distant past. of topical steroids to decrease
advisable to use lower energy settings inflammation and increasing the
during the procedure in order to yy There are two peak incidences for probability of patency of peripheral
avoid trabecular damage, peripheral angle recession glaucoma – within iridotomies. (Figure 8,9)
anterior synechiae, and subsequent 3 years of injury and a later onset yy Surgical intervention should be
permanent IOP elevation. after 10 years. Patients with angle considered in patients on maximum
recession should be instructed to tolerated medical treatment when
Figure 6: Selective Laser Trabeculoplasty return periodically for complete eye there is significant optic nerve
yy PDG patients require filtration evaluation even ten or more years damage from chronic/intermittent
after an injury. IOP elevation.
procedures slightly more frequently yy Inflammation must be controlled
than do patients with POAG yy In ARG, IOP peaks and fluctuations preoperatively for 3 months for
yy Young patients show more intense can be greater than those seen in optimum outcomes.
conjunctival scarring than do older POAG. yy The postoperative inflammatory
patients, which increases the chances response in uveitic eyes is greater
of bleb failure. This should be taken yy Miotics may be ineffective in ARG requiring more frequent topical
into account when performing and prostaglandin analogues may be steroid instillations along with
trabeculectomy in PDG eyes, since relatively contraindicated if there is cycloplegics and frequent follow
patients are usually younger than inflammation.
those with POAG. Figure 8: Iris Bombé formation in a patient
yy PDG patients experience a higher yy Surgical intervention is required in with uveitic glaucoma and secculusio
rate of steroid responsiveness the form of filtering surgery/valves if pupillae
which should be kept in mind in IOP is uncontrolled.
postoperative period. Figure 9: Multiple Peripheral Iridotomies
yy Young PDG patients may experience yy The patient with ARG may in a patient with iris bombe and uveitic
a higher rate of hypotony be younger than the typical glaucoma
maculopathy after trabeculectomy. glaucoma patient, which can affect
Glaucoma Management In outcomes of filtering surgery. Use
Angle Recession Glaucoma of Antimetabolites during the
(ARG) glaucoma filtering surgery becomes
yy There is a strong correlation between imperative in these cases.
hyphaema post traumatic injury and
angle recession (Figure 7). Glaucoma Management in
Uveitic Glaucomas
yy Glaucoma is seen in approximately
10% of patients with uveitis.
yy Uveitic glaucoma initially should
be managed medically – to decrease
inflammation and IOP. However,
glaucoma medications can often
46 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
Subspeciality-Glaucoma
ups. A closer watch to be kept on yy Oral acetazolamide and intravenous yy Themostcommoncauseoftreatment
development of cystoid macular mannitol may be used with caution failure in NVG is progression of
edema post surgery. in the patient population due to underlying disease.
Glaucoma Management in a high prevalence of concomitant
Neovascular Glaucoma (NVG) renal disease. Conclusion
(Figure 10, 11) Glaucoma can have varied presentation
yy Aqueous suppressants, beta- yy Intense topical corticosteroids inclinicalpractice.Theabovementioned
blockers, carbonic anhydrase are recommended to quell the special cases can be encountered in
inhibitors (topical and oral), and prominent inflammatory response ophthalmology/speciality clinics. Their
alpha adrenergics are the mainstay in NVG. management can be challenging and
of treatment for the lowering of IOP the above mentioned pearls can help in
in NVG. yy Topical atropine is also their management.
recommended for symptomatic Suggested Reading
Figure 10: Neovascularisation of iris seen relief and decrease inflammation in • Becker-Shaffer’s Diagnosis and
in a patient of Neovascular glaucoma on NVG.
diffuse illumination on slit lamp Therapy of the Glaucomas: 8th edition.
yy Prompt PRP of underlying disease • Shield’s textbook of glaucoma: 6th
Figure 11: Neovascularisation of angle on is vital to the preservation of
gonioscopic examination vision in NVG. PRP should ideally edition
be performed 2–3 weeks prior to • JoAnn A. Giaconi, Simon
glaucoma surgery to allow for
surgery in an uninflamed eye with K. Law, Anne L. Coleman,
regressed neovascularization. But Joseph Caprioli (Eds.). Pearls of
this is often not possible due to glaucoma management. Springer
hazy ocular media or significantly publications.
elevated IOP despite maximal
medical management. Corresponding Author:
yy Intravitreal Anti VEGF injections Dr Jatinder Singh Bhalla
can be given three days prior to MS, DNB, MNAMS
any glaucoma surgery to help in HOD (Ophthalmology)
regression of neovascularisation. DDU Hospital, New Delhi 110064
Tube shunts are usually the preferred
surgical technique in NVG, but
trabeculectomy can be as effective as
tube implants.
yy Despite regression of Neo-
Vascularisation from effective PRP
or anti-VEGF therapy, surgery is still
required to control NVG if angle-
closure has developed.
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Subspeciality-Glaucoma
UBM Imaging and Glaucoma
Jatinder Singh Bhalla, Ashwini Kulkarni, Kanika Jain , Satender Singh,
Thory Prakash, Yogesh, Neha Yadav
Department of Ophthalmology , Deen Dayal Upadhyay Hospital, Hari Nagar, New Delhi
Introduction UBM can be used as a method of
Ultrasound biomicroscopy (UBM) imaging ocular pathology, from
was first developed by Pavlin’s group adnexal, conjunctiva, scleral, corneal,
in Canada in 1989 (Pavlin, Sherar, et anterior chamber to anterior vitreous
al, 1990). As it could provide images and has majorly contributed to the
of the tissues and structures in vivo understanding of the structure of
at microscopic resolution, similar to the anterior segment, particularly in
optical biomicroscopy, Pavlin’s group glaucoma.
termed it ‘ultrasound biomicroscopy’. Figure 3 illustrates major anatomical
landmarks as seen on UBM images.
Instead of using the 10 MHz which
is most widely used in ophthalmic Figure 4: Imaging technique while
diagnostic ultrasound (such as in A-scan performing UBM. The lower flange fits
or B-scan), UBM (Figure 1-shows UBM under the lids holding the cup on the eye.
machine) uses ultrasound frequencies Filling the cup with normal saline. An eye
in the 50MHz (Figure 2-shows UBM cup in the place and probe being placed in
probe) to 100 MHz range, conferring the eye cup to perform UBM.
very high resolution of up to 20um
axially and 50um laterally, and depth of
tissue penetration of 4-5mm.
Figure 1: UBM machine Figure 3: Illustration of major anatomical lucent coupling fluid such as
Figure 2: 50 MHz UBM probe landmarks in UBM images. (C: Cornea; methylcellulose (1-2.5%). Some
AC: Anterior chamber; S: Scleral spur; CB: examiners use normal saline to fill
Ciliary body; PC: Posterior chamber; LC: the cup after sealing the interface
Lens capsule; L: Lens). between the eye and the base of the
cup with 2.5% methylcellulose.
Imaging technique (Figure 4) • A mark on the probe is present
• The patient is examined in a supine which appears on the right side of
the screen. Transducer direction
position fixating the gaze ahead at and manipulation of the probe is
the ceiling. guided by looking at the image on
• After topical anaesthesia, a the screen.
specially-designed eyecup (22 to 24 • Scans are usually taken with
mm diameter) is used to separate marker kept nasally scanning the
the eyelids and form a water bath 9 to 3 o’Clock meridian, asking
environment. the patient to look straight ahead
• This is filled with a viscous, sono- followed by nasally (to view 9
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Subspeciality-Glaucoma
O’ clock of patient’s eye) then • The Anterior Chamber (AC) is seen Figure 6: Ciliary body region: Up arrow
temporally (to view 3 O’ clock). as an echo poor area between the shows the ciliary processes and down arrow
Scans are then taken with marker cornea and the iris. The AC depth the ciliary body
kept superiorly scanning the 6 to can be measured from the posterior Figure 7: Image through a ciliary process
12o’Clock meridian, asking the surface of the cornea to the anterior (open arrow). The zonule can be seen
patient to look straight ahead capsule. The normal AC depth is extending from the ciliary process to the lens
followed by upward gaze (to view 2.5-3.0 mm. surface (closed arrow).
6O’ clock) then downward gaze (to
view 12O’ clock). • The iris is seen as a flat uniform Figure 8: Transverse section of ciliary
• Images are stored in an electronic echogenic area. The iris and ciliary processes
format on a computer attached to body converge in the iris recess and Figure 9: UBM image demonstrating
the device. insert into the scleral spur. The area Anterior Chamber Depth (ACD), Pupillary
• Patient’s name, ID number, date of under the peripheral iris and above Diameter (PD), Lens Vault (LV), Anterior
examination and laterality of eye the ciliary processes is defined as Chamber Width (ACW), Scleral Spur (SS)
are stored in a separate file. the ciliary sulcus.
• Reviewing images and the
derivation of measurements from • The angle can be studied in a cross-
the images has to be done on the section by orienting the probe in
UBM’s computer unit or a PC which a radial fashion at the limbus. The
uses suitable software to process scleral spur (protrusion of sclera
and display the images. into the anterior chamber) is the
Normal anatomy (Figure 3) most important landmark in the
and parameters measured angle on UBM. The scleral spur is
using UBM seen as small hyperechogenic spot
• The cornea is the first structure when the line between the sclera
seen on UBM [Figure 5]. The corneal and ciliary body is traced to the AC.
layers are well-differentiated. The
Bowman’s membrane is seen as • The ciliary body can be clearly
a first dense echo. The stroma defined by UBM from the ciliary
shows low irregular reflectivity. processes to the para plana [Figure
The desment’s membrane- 6,7]. The ciliary processes vary in
corneal endothelium is seen as a appearances and configuration
dense highly reflective line. The [Figure 8]. The individual processes
corneoscleral junction can be are better seen in a transverse
differentiated because of the lower section through the ciliary
internal reflectivity of the cornea processes.
compared to the sclera.
• The posterior ciliary body tapers off
Figure 5: Ultrasound biomicroscopic image toward the para plana. The anterior
of normal cornea. The top echo is from the zonular surface can be consistently
epithelial surface. The second echo just below imaged by UBM [Figure 7]. The
this is from Bowman’s membrane. The zonules are seen as a medium
corneal stroma shows weak backscatter. reflective line extending from the
The endothelium-Descemet’s layer provides ciliary processes to the lens surface.
a bright echo at the interface with aqueous.
• Central Anterior Chamber Depth
(cACD): It is measured between
the anterior surface of the lens and
the corneal endothelium along the
central axis (Figure 9).
• Anterior Chamber Area (ACA): It is
the area surrounded by the anterior
surface of the iris, the lens within
the pupil and the endothelial
surface of the cornea.
• Angle Opening Distance at 500 µm
(AOD500): It is calculated as the
perpendicular distance from the
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Subspeciality-Glaucoma
trabecular meshwork at 500 µm • Trabecular-ciliary process distance Figure 13: UBM parameters Iris Thickness
anterior to the scleral spur to the (TCPD): It is measured on a line at 750 μm (IT750), Iris Thickness at 2000
anterior iris surface (Figure 10). extending from the corneal μm (IT2000)
• Angle Opening Distance at 750 µm endothelium at 500 µm from the
(AOD750): It is calculated as the scleral spur passing perpendicularly • Iris-lens contact distance (ILCD) is
perpendicular distance from the through iris to the ciliary process measured along the iris pigmented
trabecular meshwork at 750 µm (Figure 11). epithelium from the pupillary
anterior to the scleral spur to the border to the point where the
anterior iris surface (Figure 10). • Iris thickness 1 (ID1) is measured anterior lens surface leaves the iris.
• Trabecular Iris Surface Area at 500 along the same line as the TCPD
µm (TISA500): It is the trapezoidal (Figure 12,13). • Iris lens angle is the angle between
area with the following boundaries: the iris and the lens near the
anteriorly the AOD500, posteriorly • Iris thickness 2 (ID2) is measured at pupillary edge.
a line drawn from the scleral spur 2 mm (2000 μm) from the iris root
perpendicular to the plane of inner (Figure 12,13). • Scleral-iris angle (SIA) is measured
scleral wall to the opposing iris, between the tangent to the scleral
superiorly the inner corneoscleral • Iris thickness 3 (ID3) is measured surface and the long axis of the iris.
wall and inferiorly the anterior iris at the maximum iris thickness near
surface (Figure 10). the pupillary edge. (Figure 12) • Scleral-ciliary process angle
• Trabecular Iris Surface Area at 750 (SCPA) is measured between the
µm (TISA750): It is the trapezoidal • Iris-ciliary process distance (ICPD) tangent to the scleral surface and
area with the following boundaries: is the distance measured from the the long axis of the ciliary process.
anteriorly the AOD750, posteriorly posterior surface of the iris to the
a line drawn from the scleral spur ciliary process along the same line • Lens Vault (LV): Lens vault will
perpendicular to the plane of inner as TCPD. be the maximum perpendicular
scleral wall to the opposing iris, distance from a horizontal line
superiorly the inner corneoscleral Figure 11: Assessment of ciliary body between the two scleral spurs to
wall and inferiorly the anterior iris parameters such as Trabecular-ciliary the anterior surface of the lens
surface (Figure 10). process distance (TCPD), Iris thickness 1 (Figure 9).
• Angle Recess Area at 750 µm (ID1), Trabecular–Ciliary Angle (TCA)
(ARA750): It is defined as the • Lens Thickness (LT)
triangular area, the base of which is Figure 12: Diagram of measurement
formed by AOD750, apex is formed positions for the iris. The iris is measured • Maximum Ciliary Body Thickness
by angle recess and the sides of the at three points along its length. The first (CBTmax): It is the distance from
triangle are formed by anterior iris measurement (lD 1) is located on a line the most inner point of the ciliary
surface and inner corneoscleral perpendicular to the iris connecting a processes to the inner wall of sclera
wall. point on the trabecular meshwork 500 µm or its extended line (Figure 14).
from the scleral spur to the ciliary process
Figure 10: UBM scan showing parameters (trabecular-ciliary process distance, TCPD). • Ciliary Body Thickness at the point
Angle Opening Distance at 500 µm The second (ID2) is measured 2 mm from of the scleral spur is termed as
(AOD500), Angle Opening Distance at 750 the scleral spur. The third (ID3) is measured CBT0 (Figure 14).
µm (AOD750), Trabecular Iris Surface at the thickest point near the iris margin.
Area at 500 µm (TISA500), Trabecular Iris • Ciliary Body Thickness at the
Surface Area at 750 µm (TISA750) distance of 1000 μm from the
scleral spur is termed as CBT1000
(Figure 14).
• Anterior Placement of Ciliary Body
(APCB) is the distance from the
50 DOS Times - Volume 26, Number 4, January-February 2021 www.dosonline.org/dos-times
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