5_6289834143039619076

190 Comprehensive OPHTHALMOLOGY

Fig. 8.18. Surgical steps of conventional extracapsular cataract extraction with posterior chamber intraocular
lens implantation: A, anterior capsulotomy can-opener's technique; B, removal of anterior capsule; C, completion of
corneo-scleral section; D, removal of nucleus (pressure and counter-pressure method); E, aspiration of cortex; F,
insertion of inferior haptic of posterior chamber IOL; G, insertion of superior haptic of PCIOL; H, dialing of the IOL;

I, corneo-scleral suturing.

DISEASES OF THE LENS 191

Surgical steps of manual SICS are (Fig. 8.19) : hydrodissection and completed by rotating the
nucleus with Sinskey's hook (Fig. 8.19K).
1. Superior rectus (bridle) suture is passed to fix the ii. Delivery of the nucleus outside through the
eye in downward gaze (Fig. 8.19A). This is specifically corneo-scleral tunnel can be done by any of the
important in manual SICS where in addition to fixation following methods:
of globe, it also provides a countertraction force
during delivery of nucleus and epinucleus. Irrigating wire vectis method (Fig. 8.19L). (It is
2. Conjunctival flap and exposure of sclera (Fig. the most commonly used method).
8.19B). A small fornix based conjunctival flap is made Blumenthal's technique,
with the help of sharp-tipped scissors along the Phacosandwitch technique,
limbus from 10 to 2 O’clock positions. Conjunctiva Phacofracture technique, and
and the Tenon's capsule are dissected, seperated from Fishhook technique.
the underlying sclera and retracted to expose about 4 9. Aspiration of cortex. The remaining cortex is
mm strip of sclera along the entire incision length. aspirated out using a two-way irrigation and
3. Haemostasis is achieved by applying gentle and aspiration cannula (Fig. 8.19M) from the main incision
just adequate wet field cautery. and/or side port entry.
4. Sclero-corneal tunnel incision. A self-sealing 10. IOL implantation. A posterior chamber IOL is
sclero-corneal tunnel incision is made in manual SICS. implanted in the capsular bag after filling the bag with
It consists of following components: viscoelastic substance (Figs. 8.19N, O & P)
i. External scleral incision. A one-third to half- 11. Removal of viscoelastic material is done
thoroughly from the anterior chamber and capsular
thickness external scleral groove is made about bag with the help of two-way irrigation aspiration
1.5 to 2mm behind the limbus. It varies from 5.5 cannula.
mm to 7.5 mm in length depending upon the 12. Wound closure.The anterior chamber is deepened
hardness of nucleus. It may be straight, frown with balanced salt solution / Ringer's lactate solution
shaped or chevron in configuration (Figs. 18.19C, injected through side port entry. This leads to self
D & E). sealing of the sclero-corneal tunnel incision due to
ii. Sclero-corneal tunnel. It is made with the help of valve effect. Rarely a single infinity suture may be
a crescent knife. It usually extends 1-1.5 mm into required to seal the wound. The conjunctival flap is
the clear cornea (Fig. 8.19F). reposited back and is anchored with the help of wet
iii. Internal corneal incision. It is made with the field cautery (Fig. 8.19Q).
help of a sharp 3.2 mm angled keratome
(Fig. 8.19G). PHACOEMULSIFICATION
5. Side-port entry of about 1.5-mm valvular corneal
incision is made at 9 o'clock position (Fig. 8.19H). It is presently the most popular method of
This helps in aspiration of the sub-incisional cortex extracapsular cataract extraction. It differs from the
and deepening the anterior chamber at the end of conventional ECCE and manual SICS as follows:
surgery.
6. Anterior capsulotomy. As described in 1. Corneoscleral incision required is very small (3
conventional ECCE, the capsulotomy in manual SICS mm). Therefore, sutureless surgery is possible
can be either a canopner, or envelope or CCC. with self-sealing scleral tunnel or clear corneal
However, a large sized CCC is preferred (Fig. 8.19I). incision made with a 3 mm keratome.
7. Hydrodissection. As described in ECCE
hydrodissection (Fig. 8.19J) is essential to separate 2. Continuous curvilinear capsulorrhexis (CCC) of
corticonuclear mass from the posterior capsule in 4-6 mm is preferred over other methods of anterior
SICS. capsulotomy (Fig. 8.20A).
8. Nuclear management. It consists of following
manoeuvres : 3. Hydrodissection i.e., separation of capsule from
i. Prolapse of nucleus out of the capsular bag into the cortex by injecting fluid exactly between the
the anterior chamber is usually initiated during two (Fig. 8.20B) is must for phacoemulsification
in SICS. This procedure facilitates nucleus
rotation and manipulation during phacoemulsifica-
tion. Some surgeons also perform hydrodelineation
(Fig. 8.20C).

192 Comprehensive OPHTHALMOLOGY

Fig. 8.19. Surgical steps of manual small incision cataract surgery (SICS): A, Superior rectus bridle suture;
B Conjunctival flap and exposure of sclera; C, D & E, External Scleral incisions (straight, frown shaped, and chevron,
respectively) part of tunnel incision; F, Sclero-corneal tunnel with crescent knife; G, Internal corneal incision; H, Side port
entry; I, Large CCC; J, Hydrodissection; K, Prolapse of nucleus into anterior chamber; L, Nucleus delivery with irrigating
wire vectis; M, Aspiration of cortex; N, insertion of inferior haptic of posterior chamber IOL; O, Insertion of

superior haptic of PCIOL; P, Dialing of the IOL, Q, Reposition and anchoring of conjunctival flap.

DISEASES OF THE LENS 193

4. Nucleus is emulsified and aspirated by The corneo-scleral tunnel techniques (closed
phacoemulsifier. Phacoemulsifier basically acts chamber surgery) as described for SICS is preferred
through a hollow 1-mm titanium needle which over the conventional ECCE technique (open chamber
vibrates by piezoelectric crystal in its longitudinal surgery).
axis at an ultrasonic speed of 40000 times a Surgical steps of irrigation and aspiration of lens
second and thus emulsifies the nucleus. Many matter by corneo-scleral tunnel incision
different techniques are being used to accomplish techniques are as follows :
phacoemulsification. A few common names are 1 to 5 initial steps upto making of side port entry are
‘chip and flip technique’, ‘divide and conquer similar as described for manual SICS in adults (page
technique’ (Figs. 8.20 D&E) ‘stop and chop’ and 191 Figs. 8.19A to H).
‘phaco chop technique’. 6. Anterior capsulorhexis of about 5mm size is made
as described on page 189 (Figs. 8.20A). In children
5. Remaining cortical lens matter is aspirated with the anterior capsule is more elastic than in adults and
the help of an irrigation-aspiration technique therefore, the capsulorhexis may be difficult due to
(Fig. 8.20F). tendency to run outwards.
7. Irrigation and aspiration of lens matter (which
6. Next steps i.e., IOL implantation, removal of is soft in children) can be done by any of the following
viscoelastic substance and wound closure are methods :
similar to that of SICS. Foldable IOL is most ideal
with phacoemulsification technique. With two-way irrigation and aspiration Simcoe
cannula (Fig. 8.19M) or,
Phakonit. Phakonit refers to the technique of With a phacoprobe (phaco-aspiration) (Fig. 8.20F)
phacoemulsification (PHAKO) performed with a 8. Posterior capsulorhexis of about 3-4 mm size is
needle (N) opening via an incision (I) using the tip recomnended in children to avoid the problem of
(T) of phacoprobe. In this technique the size of posterior capsule opacification.
incision is only 0.9 mm and after completion of the 9. Anterior vitrectomy of limited amount should be
operation an ultrathin rollable IOL is inserted into the performed with a vitrector.
capsular bag. This technique offers almost nil 10. Implantation of IOL is done in the capsular bag
astigmatism cataract surgery. after inflating it with viscoelastic substance (Figs.
8.19N, O&P). Heparin or fluorine coated PMMA IOLs
Laser phacoemulsification. This technique is under are preferred in children. Some surgeons prefer to
trial and perhaps may soon replace the conventional capture the lens optic through posterior
phacoemulsification. In it the lens nucleus is capsulorhexis.
emulsified utilizing laser energy. The advantage of Note: Steps 8 and 9, and optic capture as described in
this technique is that the laser energy used to emulsify step 10 are measures to prevent formation of after
cataractous lens is not exposed to other intraocular cataract, the incidence of which is very high in
structures (c.f. ultrasonic energy). children.
11. Removal of viscoelastic substance is done with
SURGICAL TECHNIQUES OF EXTRACAPSULAR the help of two-way cannula.
CATARACT EXTRACTION FOR CHILDHOOD 12. Wound closure. Though a well constructed
CATARACT corneo-scleral tunnel often does not require a suture,
but placement of one horizontal suture (with 10-0
Surgical techniques employed for childhood cataract nylon) ensures wound stability and reduces
are essentially of two types: postoperative astigmatism.

Irrigation and aspiration of lens matter, and 2. Lensectomy
Lensectomy
In this operation most of the lens including anterior
1. Irrigation and aspiration of lens matter and posterior capsule along with anterior vitreous
are removed with the help of a vitreous cutter, infusion
Irrigation and aspiration of lens matter can be done
by:
i. Conventional ECCE technique, or
ii. Corneo-scleral tunnel techniques which include :

Manual SICS technique, and
Phaco-aspiration technique

194 Comprehensive OPHTHALMOLOGY

Fig. 8.20. Surgical steps of phacoemulsification : A, Continuous curvilinear capsulorrhexis; B, Hydrodissection;
C, Hydrodelineation; D&E; Nucleus emulsification by divide and conquer technique (four quadrant cracking);

F, Aspiration of cortex.

and suction machine (Fig. 8.21). Childhood cataracts, Fig. 8.21. Kaufman’s vitrector.
both congenital/developmental and acquired, being
soft are easily dealt with this procedure especially in
very young children (less than 2 years of age) in which
primary IOL implantation is not planned. Lensectomy
in children is performed under general anaesthesia.
Either pars plana or limbal approach may be adopted.
In pars plana approach, the lens is punctured at its
equator and stirred with the help of a Ziegler’s or any
other needle-knife introduced through the sclera and
ciliary body, from a point about 3.5-4 mm behind
the limbus. The cutter (ocutome) of the vitrectomy
machine is introduced after enlarging the sclerotomy
(Fig. 8.22) and lensectomy along with anterior
vitrectomy is completed using cutting, irrigation
and aspiration mechanisms. The aim of modern
lensectomy is to leave in situ a peripheral rim of
capsule as an alternative to complete lensectomy.
Secondary IOL implantation can be planned at a
later date.

DISEASES OF THE LENS 195

Fig. 8.22. Pars plana lensectomy. 2. Iris-supported lenses. These lenses are fixed on
the iris with the help of sutures, loops or claws.
INTRAOCULAR LENS IMPLANTATION These lenses are also not very popular due to a
high incidence of postoperative complications.
Presently, intraocular lens (IOL) implantation is the Example of iris supported lens is Singh and Worst’s
method of choice for correcting aphakia. Its iris claw lens (Figs. 8.24B and 8.25).
advantages and disadvantages over spectacles and 3. Posterior chamber lenses. PCIOLs rest entirely
contact lenses are described in aphakia (see page behind the iris (Fig. 8.26). They may be supported by
31). the ciliary sulcus or the capsular bag. Recent trend is
towards ‘in-the-bag-fixation’. Commonly used model
The IOL implant history had its beginning on of PCIOLs is modified C-loop (Fig. 8.24C).
November 29, 1949, when Harold Ridley, a British
ophthalmologist, performed his first case. Since then Depending on the material of manufacturing, three
history of IOLs has always been exciting, often types of PC-IOLs are available :
frustrating and finally rewarding and now highly i. Rigid IOLs. The modern one piece rigid IOLs are
developed.
made entirely from PMMA.
Types of intraocular lenses ii. Foldable IOLs, to be implanted through a small

During the last two decades a large number of incision (3.2 mm) after phacoemulsification are
different types and styles of lenses have been made of silicone, acrylic, hydrogel and collamer.
developed. The commonly used material for their iii. Rollable IOLs are ultra thin IOLs. These are
manufacture is polymethylmethacrylate (PMMA). implanted through micro incision (1mm) after
The major classes of IOLs based on the method of phakonit technique. These are made of hydrogel.
fixation in the eye are as follows: Indications of IOL implantation
Recent trend is to implant an IOL in each and every
1. Anterior chamber IOL. These lenses lie entirely case being operated for cataract; unless it is
in front of the iris and are supported in the angle contraindicated. However, operation for unilateral
of anterior chamber (Fig. 8.23). ACIOL can be cataract should always be followed by an IOL
inserted after ICCE or ECCE. These are not very implantation.
popular due to comparatively higher incidence of
bullous keratopathy. When indicated, ‘Kelman Fig. 8.23. Pseudophakia with Kelman Multiflex anterior
multiflex’ (Fig. 8.24A) type of ACIOL is used chamber intraocular lens implant.
commonly.

196 Comprehensive OPHTHALMOLOGY

AB C

Fig. 8.24. Types of intraocular lenses: A, Kelman multiflex (an anterior chamber IOL); B, Singh & Worst's iris claw lens;
C, posterior chamber IOL – modified C-loop type.

Fig. 8.25. Pseudophakia with iris claw intraocular Calculation of IOL power (Biometry)
lens implant.
The most common method of determining IOL power
uses a regression formula called ‘SRK (Sanders,
Retzlaff and Kraff) formula’. The formula is P = A –
2.5L – 0.9K, where:

P is the power of IOL,
A is a constant which is specific for each lens
type.
L is the axial length of the eyeball in mm, which
is determined by A-scan ultrasonography.
K is average corneal curvature, which is
determined by keratometry.
The ultrasound machine equipped with A-scan
and IOL power calculation software is called
‘Biometer’.

AB

Fig. 8.26. Pseudophakia with posterior chamber intraocular lens A : As seen on retroillumination with slit-lamp;
B, Diagrammatic depiction of PCIOL implanted in the capsular bag.

DISEASES OF THE LENS 197

Primary versus secondary IOL implantation 5. After 6-8 weeks of operation corneoscleral sutures
are removed (when applied). Now a days most
Primary IOL implantation refers to the use of IOL surgeons are doing sutureless cataract surgery.
during surgery for cataract, while secondary IOL is
implanted to correct aphakia in a previously operated 6. Final spectacles are prescribed after about 8 weeks
eye. of operation.

Surgical technique of anterior chamber IOL COMPLICATIONS OF CATARACT
implantation SURGERY AND THEIR MANAGEMENT

Anterior chamber IOL implantation can be carried out Now-a-days cataract surgery is being performed
after ICCE and ECCE. After completion of lens largely by extracapsular cataract extraction technique.
extraction, the pupil is constricted by injecting miotics Therefore, complications encountered during these
(1 percent acetylcholine or pilocarpine without techniques are described in general. Wherever
preservatives) into the anterior chamber. Anterior necessary a specific reference of the technique viz.
chamber is filled with 2 percent methylcellulose or 1 conventional ECCE, manual SICS and
percent sodium hyaluronate (Healon). The IOL, held phacoemulsification in relation to the particular
by a forceps, is gently slid into the anterior chamber. complication is highlighted.
Inferior haptic is pushed in the inferior angle at 6
O'clock position and upper haptic is pushed to Complications encountered during surgical
engage in the upper angle (Figs. 8.17 G & H). management of cataract can be enumerated under the
following heads:
Technique of posterior chamber IOL implantation (A) Preoperative complications
(B) Intraoperative complications
Implantation of rigid intraocular lens. PCIOL is (C) Early postoperative complications
implanted after ECCE. After completion of ECCE, the (D) Delayed (late) postoperative complications
capsular bag and anterior chamber are filled with 2 (E) IOL-related complications
percent methylcellulose or 1 percent sodium
hyaluronate. The PCIOL (Fig. 8.24C), is grasped by [A] Preoperative complications
the optic with the help of IOL holding forceps. The
inferior haptic and optic of IOL is gently inserted into 1. Anxiety. Some patients may develop anxiety, on
the capsular bag behind the iris at 6 O'clock position the eve of operation due to fear and apprehension of
(Fig. 8.18F). The superior haptic is grasped by its tip, operation. Anxiolytic drugs such as diazepam 2 to 5
and is gently pushed down and then released to slide mg at bed time usually alleviate such symptoms.
in the upper part of the capsular bag behind the iris 2. Nausea and gastritis. A few patients may develop
(Fig. 8.18G). The IOL is then dialled into the horizontal nausea and gastritis due to preoperative medicines
position (Fig. 8.18H). such as acetazolamide and/or glycerol. Oral antacids
Implantation of foldable IOLs is made either with the and omission of further dose of such medicines
help of holder-folder forceps or the foldable IOLs usually relieve the symptoms.
injector. 3. Irritative or allergic conjunctivitis may occur in
some patients due to preoperative topical antibiotic
POSTOPERATIVE MANAGEMENT AFTER drops. Postponing the operation for 2 days along
CATARACT OPERATION with withdrawal of such drugs is required.
4. Corneal abrasion may develop due to inadvertent
1. The patient is asked to lie quietly upon the back injury during Schiotz tonometry. Patching with
for about three hours and advised to take nil antibiotic ointment for a day and postponement of
orally. operation for 2 days is required.
5. Complications due to local anaesthesia
2. For mild to moderate postoperative pain injection
diclofenac sodium may be given. Retrobulbar haemorrhage may occur due to
retrobulbar block. Immediate pressure bandage
3. Next morning bandage is removed and eye is after instilling one drop of 2% pilocarpine and
inspected for any postoperative complication. postponement of operation for a week is advised.

4. Antibiotic-steroid eyedrops are used for four
times, three times, two times and then once a day
for 2 weeks each.

198 Comprehensive OPHTHALMOLOGY

Oculocardiac reflex, which manifests as Premature entry into the anterior chamber
bradycardia and/or cardiac arrhythmia, has also can occur because of deep dissection
been observed due to retrobulbar block. An (Fig. 8.27C). Once this is detected, dissection
intravenous injection of atropine is helpful. in that area should be stopped and a new
Perforation of globe may also occur sometimes. dissection started at a lesser depth at the
To prevent such catastrophy, gentle injection other end of the tunnel.
with blunt-tipped needle is recommended. Further, Scleral disinsertion can occur due to very
peribulbar anaesthesia may be preferred over deep groove incision. In it there occurs
retrobulbar block. complete separation of inferior sclera from the
Subconjunctival haemorrhage is a minor sclera superior to the incision (Fig. 8.27D).
complication observed frequently, and does not Scleral disinsertion needs to be managed by
need much attention. radial sutures.
Spontaneous dislocation of lens in vitreous has 4. Injury to the cornea (Descemet's detachment),
also been reported (in patients with weak and iris and lens may occur when anterior chamber is
degenerated zonules especially with hypermature entered with a sharp-tipped instrument such as
cataract) during vigorous ocular massage after keratome or a piece of razor blade. A gentle handling
retrobulbar block. The operation should be with proper hypotony reduces the incidence of such
postponed and further management is on the inadvertent injuries.
lines of posterior dislocation of lens (page 204). 5. Iris injury and iridodialysis (tear of iris from root)
may occur inadvertently during intraocular
[B] Operative complications manipulation.
6. Complications related to anterior capsulorhexis.
1. Superior rectus muscle laceration and/or Continuous curvilinear capsulorhexis (CCC) is the
haematoma, may occur while applying the bridle preferred technique for opening the anterior capsule
suture. Usually no treatment is required. for SICS and phacoemulsification. Following
2. Excessive bleeding may be encountered during complications may occur:
the preparation of conjunctival flap or during incision Escaping capsulorhexis i.e., capsulorhexis moves
into the anterior chamber. Bleeding vessels may be peripherally and may extend to the equator or
gently cauterised. posterior capsule.
3. Incision related complications depend upon the Small capsulorhexis. It predisposes to posterior
type of cataract surgery being performed. capsular tear and nuclear drop during
i. In conventional ECCE there may occur irregular hydrodissection. It also predisposes to occurrence
of zonular deshiscence. Therefore, a small sized
incision. Irregular incision leading to defective capsulorhexis should always be enlarged by 2 or
coaptation of wound may occur due to blunt 3 relaxing incisions before proceeding further.
cutting instruments. Very large capsulorhexis may cause problems
ii. In manual SICS and phacoemulsification for in the bag placement of IOL.
following complications may occur while making Eccentric capsulorhexis can lead to IOL
the self-sealing tunnel incision. decentration at a later stage.

Button holing of anterior wall of tunnel can
occur because of superficial dissection of the
scleral flap (Fig. 8.27B). As a remedy, abandon
this dissection and re-enter at a deeper plane
from the other side of the external incision.

A BC D

Fig. 8.27. Configuration of sclerocorneal tunnel incision: A, correct incision; B, Buttonholing of anterior wall of the tunnel;
C, Premature entry into the anterior chamber; and D, Scleral disinsertion.

DISEASES OF THE LENS 199

7. Posterior capsular rupture (PCR). It is a dreaded A meticulously performed partial anterior
complication during extracapsular cataract extraction. vitrectomy will reduce the incidence of postoperative
In manual SICS and phacoemulsification PCR is even problems associated with vitreous loss such as
more feared because it can lead to nuclear drop into updrawn pupil, iris prolapse and vitreous touch
the vitreous. The PCR can occur in following syndrome.
situations: 10. Nucleus drop into the vitreous cavity. It occurs
more frequently with phacoemulsification, less
During forceful hydrodissection, frequently with manual SICS and sparingly with
By direct injury with some instrument such as conventional ECCE. It is a dreadful complication which
Sinskey's hook, chopper or phacotip, and occurs due to sudden and large PCR.
During cortex aspiration (accidental PCR) Management. Once the nucleus has dropped into
8. Zonular dehiscence may occur in all techniques of the vitreous cavity, no attempt should be made to
ECCE but is especially common during nucleus fish it out. The case must be referred to vitreoretinal
prolapse into the anterior chamber in manual SICS. surgeon after a thorough anterior vitrectomy and
9. Vitreous loss: It is the most serious complication cortical clean up.
which may occur following accidental rupture of 11. Posterior loss of lens fragments into the vitreous
posterior capsule during any technique of ECCE. cavity may occur after PCR or zonular dehiscence
Therefore, adequate measures as described below during phacoemulsification. It is potentially serious
should be taken to prevent vitreous loss. because it may result in glaucoma, chronic uveitis,
To decrease vitreous volume: Preoperative use chronic CME and even retinal detachment.
of hyperosmotic agents like 20 percent mannitol Management. The case should be managed by
or oral glycerol is suggested. vitreoretinal surgeon by performing pars plana
To decrease aqueous volume: Preoperatively vitrectomy and removal of nuclear fragments.
acetazolamide 500 mg orally should be used and 12. Expulsive choroidal haemorrhage. It is one of
adequate ocular massage should be carried out the most dramatic and serious complications of
digitally after injecting local anaesthesia. cataract surgery. It usually occurs in hypertensives
To decrease orbital volume adequate ocular and patients with arteriosclerotic changes. It may
massage and orbital compression by use of occur during operation or during immediate
superpinky, Honan's ball, or 30 mm of Hg pressure postoperative period. Its incidence was high in ICCE
by paediatric sphygmomanometer should be and conventional ECCE but has decreased markedly
carried out. with valvular incision of manual SICS and phaco
Better ocular akinesia and anaesthesia decrease emulsification technique.
the chances of pressure from eye muscle.
Minimising the external pressure on eyeball by It is characterised by spontaneous gaping of the
not using eye speculum, reducing pull on bridle wound followed by expulsion of the lens, vitreous,
suture and overall gentle handling during surgery. retina, uvea and finally a gush of bright red blood.
Use of Flieringa ring to prevent collapse of Although treatment is unsatisfactory, the surgeon
sclera especially in myopic patients decreases should attempt to drain subchoroidal blood by
the incidence of vitreous loss. performing an equatorial sclerotomy. Most of the time
When IOP is high in spite of all above measures eye is lost and so evisceration operation has to be
and operation cannot be postponed, in that performed.
situation a planned posterior-sclerotomy with
drainage of vitreous from pars plana will prevent [C] Early postoperative complications
rupture of the anterior hyaloid face and vitreous
loss. 1. Hyphaema. Collection of blood in the anterior
Management of vitreous loss. Once the vitreous loss chamber may occur from conjunctival or scleral
has occurred, the aim should be to clear it from the vessels due to minor ocular trauma or otherwise.
anterior chamber and incision site. This can be Treatment. Most hyphaemas absorb spontaneously
achieved by performing partial anterior vitrectomy, and thus need no treatment. Sometimes hyphaema
with the use of automated vitrectors. may be large and associated with rise in IOP. In such
cases, IOP should be lowered by acetazolamide and

200 Comprehensive OPHTHALMOLOGY

hyperosmotic agents. If the blood does not get iii. Pupil block due to vitreous bulge after ICCE
absorbed in a week’s time, then a paracentesis should leads to formation of iris bombe and shallowing
be done to drain the blood. of anterior chamber. If the condition persists for
2. Iris prolapse. It is usually caused by inadequate 5-7 days, permanent peripheral anterior synechiae
suturing of the incision after ICCE and conventional (PAS) may be formed leading to secondary angle
ECCE and occurs during first or second postoperative closure glaucoma.
day. This complication is not known with manual SICS Pupil block is managed initially with mydriatic,
and phacoemulsification technique.
Management: A small prolapse of less than 24 hours hyperosmotic agents (e.g., 20% mannitol) and
duration may be reposited back and wound sutured. acetazolamide. If not relieved, then laser or surgical
A large prolapse of long duration needs abscission peripheral iridectomy should be performed to bypass
and suturing of wound. the pupillary block.
3. Striate keratopathy. Characterised by mild corneal 5. Postoperative anterior uveitis can be induced by
oedema with Descemet’s folds is a common instrumental trauma, undue handling of uveal tissue,
complication observed during immediate reaction to residual cortex or chemical reaction
postoperative period. This occurs due to endothelial induced by viscoelastics, pilocarpine etc.
damage during surgery. Management includes more aggressive use of topical
Management. Mild striate keratopathy usually steroids, cycloplegics and NSAIDs. Rarely systemic
disappears spontaneously within a week. Moderate steroids may be required in cases with severe
to severe keratopathy may be treated by instillation fibrinous reaction.
of hypertonic saline drops (5% sodium chloride) along 6. Bacterial endophthalmitis. This is one of the most
with steroids. dreaded complications with an incidence of 0.2 to 0.5
4. Flat (shallow or nonformed) anterior chamber. percent. The principal sources of infection are
It has become a relatively rare complication due to contaminated solutions, instruments, surgeon's
improved wound closure. It may be due to wound hands, patient's own flora from conjunctiva, eyelids
leak, ciliochoroidal detachment or pupil block. and air-borne bacteria.
i. Flat anterior chamber with wound leak is Symptoms and signs of bacterial endophthalmitis are
generally present between 48 and 72 hours after
associated with hypotony. It is diagnosed by surgery and include: ocular pain, diminshed vision,
Seidel's test. In this test, a drop of fluorescein is lid oedema, conjunctival chemosis and marked
instilled into the lower fornix and patient is asked circumciliary congestion, corneal oedema, exudates
to blink to spread the dye evenly. The incision is in pupillary area, hypopyon and diminished or absent
then examined with slit lamp using cobalt-blue red pupillary glow.
filter. At the site of leakage, fluorescein will be Management. It is an emergency and should be
diluted by aqueous. In most cases wound leak is managed energetically (see page 152).
cured within 4 days with pressure bandage and
oral acetazolamide. If the condition persists, [D] Late postoperative complications
injection of air in the anterior chamber and
resuturing of the leaking wound should be carried These complications may occur after weeks, months
out. or years of cataract surgery.
ii. Ciliochoroidal detachment. It may or may not be 1. Cystoid macular oedema (CME). Collection of
associated with wound leak. Detached cilio- fluid in the form of cystic loculi in the Henle’s layer of
choroid presents as a convex brownish mass in macula is a frequent complication of cataract surgery.
the involved quadrant with shallow anterior However, in most cases it is clinically insignificant,
chamber. In most cases choroidal detachment is does not produce any visual problem and undergoes
cured within 4 days with pressure bandage and spontaneous regression. In few cases, clinically
use of oral acetazolamide. If the condition significant CME typically produces visual diminution
persists, suprachoroidal drainage with injection one to three months after cataract extraction. On
of air in the anterior chamber is indicated. funduscopy it gives honeycomb appearance. On
fluorescein angiography it depicts typical flower
petal pattern due to leakage of dye from perifoveal
capillaries.

DISEASES OF THE LENS 201

In most cases it is associated with vitreous 5. Epithelial ingrowth. Rarely conjunctival epithelial
incarceration in the wound and mild iritis. Role of cells may invade the anterior chamber through a
some prostaglandins is being widely considered in defect in the incision. This abnormal epithelial
its etiopathogenesis. Therefore, immediate preopera- membrane slowly grows and lines the back of cornea
tive and postoperative use of antiprostaglandins and trabecular meshwork leading to intractable
(indomethacin or flurbiprofen or ketorolac) eyedrops glaucoma. In late stages, the epithelial membrane
is recommended as prophylaxis of CME. extends on the iris and anterior part of the vitreous.
6. Fibrous downgrowth into the anterior chamber ay
In cases of CME with vitreous incarceration, occur very rarely when the cataract wound apposition
anterior vitrectomy along with steroids and is not perfect. It may cause secondary glaucoma,
antiprostaglandins may improve visual acuity and disorganisation of anterior segment and ultimately
decrease the amount of discomfort. phthisis bulbi.
7. After cataract. It is also known as ‘secondary
2. Delayed chronic postoperative endophthalmitis cataract’. It is the opacity which persists or develops
is caused when an organism of low virulence after extracapsular lens extraction.
(Propionobacterium acne or staph epidermidis)
becomes trapped within the capsular bag. It has an Causes. (i) Residual opaque lens matter may persist
onset ranging from 4 weeks to years (mean 9 months) as after cataract when it is imprisoned between the
postoperatively and typically follows an uneventful remains of the anterior and posterior capsule,
cataract extraction with a PCIOL in the bag. surrounded by fibrin (following iritis) or blood
(following hyphaema). (ii) Proliferative type of after
3. Pseudophakic bullous keratopathy (PBK) is cataract may develop from the left-out anterior
usually a continuation of postoperative corneal epithelial cells. The proliferative hyaline bands may
oedema produced by surgical or chemical insult to a sweep across the whole posterior capsule.
healthy or compromised corneal endothelium. PBK is
becoming a common indication of penetrating Clinical types. After cataract may present as
keratoplasly (PK). thickened posterior capsule, or dense membranous
after cataract (Fig. 8.28A) or Soemmering’s ring which
4. Retinal detachment (RD). Incidence of retinal refers to a thick ring of after cataract formed behind
detachment is higher in aphakic patients as compared the iris, enclosed between the two layers of capsule
to phakics. It has been noted that retinal detachment (Fig. 8.28B) or Elschnig’s pearls in which the
is more common after ICCE than after ECCE. Other vacuolated subcapsular epithelial cells are clustered
risk factors for aphakic retinal detachment include like soap bubbles along the posterior capsule
vitreous loss during operation, associated myopia (Fig. 8.28C).
and lattice degeneration of the retina.

Fig. 8.28. Types of after cataract : A, dense membranous; B, Soemmering's ring; C, Elschnig's pearls.

202 Comprehensive OPHTHALMOLOGY

Treatment is as follows : Sun-set syndrome (Inferior subluxation of IOL).
i. Thin membranous after cataract and thickened Sun-rise syndrome (Superior subluxation of IOL).
Lost lens syndrome refers to complete dislocation
posterior capsule are best treated by YAG-laser of an IOL into the vitreous cavity.
capsulotomy or discission with cystitome or Windshield wiper syndrome. It results when a
Zeigler’s knife. very small IOL is placed vertically in the sulcus.
ii. Dense membranous after cataract needs surgical In it the superior loop moves to the left and right,
membranectomy. with movements of the head.
iii. Soemmering’s ring after cataract with clean central 3. Pupillary capture of the IOL may occur following
posterior capsule needs no treatment. postoperative iritis or proliferation of the remains of
iv. Elschnig’s pearls involving the central part of lens fibres.
4. Toxic lens syndrome. It is the uveal inflammation
the posterior capsule can be treated by YAG- excited by either the ethylene gas used for sterilising
laser capsulotomy or discission with cystitome. IOLs (in early cases) or by the lens material (in late
7. Glaucoma-in-aphakia and pseudophakia (see cases).
page 234).
[E] IOL-related complications DISPLACEMENTS OF THE LENS
In addition to the complications of cataract surgery,
following IOL-related complications may be seen: Displacement of the lens from its normal position (in
1. Complications like cystoid macular oedema, patellar fossa) results from partial or complete rupture
corneal endothelial damage, uveitis and secondary of the lens zonules.
glaucoma are seen more frequently with IOL
implantation, especially with anterior chamber and CLINICO-ETIOLOGICAL TYPES
iris supported IOLs.
UGH syndrome refers to concurrent occurrence I. Congenital displacements
of uveitis, glaucoma and hyphaema. It used to These may occur in the following forms:
occur with rigid anterior chamber IOLs, which are (a) Simple ectopia lentis. In this condition
not used now. displacement is bilaterally symmetrical and usually
2. Malpositions of IOL (Fig. 8.29). These may be in upwards. It is transmitted by autosomal dominant
the form of decentration, subluxation and dislocation. inheritance.
The fancy names attached to various malpositions of (b) Ectopia lentis et pupillae. It is characterised by
IOL are: displacement of the lens associated with slit-shaped
pupil which is displaced in the opposite direction.
Fig. 8.29. Decentered IOL. Other associations may be cataract, glaucoma and
retinal detachment.
(c) Ectopia lentis with systemic anomalies. Salient
features of some common conditions are as follows:
1. Marfan’s syndrome. It is an autosomal dominant
mesodermal dysplasia. In this condition lens is
displaced upwards and temporally (bilaterally
symmetrical) (Fig. 8.30). Systemic anomalies include
arachnodactyly (spider fingers), long extremities,
hyperextensibility of joints, high arched palate and
dissecting aortic aneurysm.
2. Homocystinuria. It is an autosomal recessive,
inborn error of metabolism. In it the lens is usually
subluxated downwards and nasally.

Systemic features are fair complexion, malar flush,
mental retardation, fits and poor motor control.

DISEASES OF THE LENS 203

6. Stickler syndrome. Ectopia lentis is occasionally
associated in this condition (details see page 270).

7. Sulphite oxidase deficiency. It is a very rare
autosomal recessive disorder of sulphur metabolism.
Ectopia lentis is a universal ocular feature. The
systemic features include progressive muscular
rigidity, decerebrate posture, and mental handicap. It
is a fatal disease, death usually occurs before 5 years
of age.

Fig. 8.30. Subluxated IOL in Marfan's syndrome. II. Traumatic displacement of the lens
It is usually associated with concussion injuries.
Diagnosis is established by detecting Couching is an iatrogenic posterior dislocation of
homocystine in urine by sodium nitro-prusside lens performed as a treatment of cataract in olden
test. days.
3. Weil-Marchesani syndrome. It is condition of
autosomal recessive mesodermal dysplasia. Ocular III. Consecutive or spontaneous displacement
features are spherophakia, and forward subluxation It results from intraocular diseases giving rise to
of lens which may cause pupil block glaucoma. mechanical stretching, inflammatory disintegration or
Systemic features are short stature, stubby fingers degeneration of the zonules. A few common
and mental retardation. conditions associated with consecutive displace-
4. Ehlers-Danlos syndrome. In it the ocular features ments are: hypermature cataract, buphthalmos, high
are subluxation of lens and blue sclera. The systemic myopia, staphyloma, intraocular tumours and uveitis.
features include hyperextensibility of joints and loose
skin with folds. TOPOGRAPHICAL TYPES
5. Hyperlysinaemia. It is an autsomal recessive Topographically, displacements of the lens may be
inborne error of metabolism occurring due to classified as subluxation and luxation or dislocation.
deficiency of the enzyme lysin alphaketoglutarate
reductase. It is an extremely rare condition I. Subluxation
occasionally associated with ectopia lentis. Systemic It is partial displacement in which lens is moved
features include lax ligaments, hypotonic muscles, sideways (up, down, medially or laterally), but remains
seizures and mental handicap. behind the pupil. It results from partial rupture or
unequal stretching of the zonules (Fig. 8.30 and
8.31A).

AB
Fig. 8.31. Displacements of lens: A, subluxation; B, anterior dislocation; C, posterior dislocation.

204 Comprehensive OPHTHALMOLOGY

Clinical feautres are as follows CONGENITAL ANOMALIES
Defective vision occurs due to marked astigmatism OF THE LENS
or lenticular myopia.
Uniocular diplopia may result from partial 1. Coloboma of the lens. It is seen as a notch in
aphakia. the lower quadrant of the equator (Fig. 8.32). It is
Anterior chamber becomes deep and irregular. usually unilateral and often hereditary.
Iridodonesis is usually present.
Dark edge of the subluxated lens is seen on 2. Congenital ectopia lentis (see lens displacement
distant direct ophthalmoscopy page 202).

Complications of subluxated lens include : 3. Lenticonus. It refers to cone-shaped elevation of
Complete dislocation, the anterior pole (lenticonus anterior, Fig. 8.33) or
Cataractous changes, posterior pole (lenticonus posterior) of the lens.
Uveitis and Lenticonus anterior may occur in Alport's
Secondary glaucoma. syndrome and lenticonus posterior in Lowe's
syndrome. On distant direct ophthalmoscopy,
Management. Spectacles or contact lens correction both present as an oil globule lying in the centre
for phakic or aphakic area (whichever is better) is of the red reflex. Slit-lamp examination confirms
helpful in many cases. Surgery is controversial and the diagnosis.
usually associated with high risk of retinal
detachment. Lensectomy with anterior vitrectomy 4. Congenital cataract. (see page 170).
may be performed in desperate cases.
5. Microspherophakia. In this condition, the lens is
II. Dislocation or luxation of the lens spherical in shape (instead of normal biconvex)
and small in size. Microspherophakia may occur
In it all the zonules are severed from the lens. A as an isolated familial condition or as a feature of
dislocated lens may be incarcerated into the pupil or other syndromes e.g., Weil-Marchesani or
present in the anterior chamber (Fig. 8.31B), the Marfan’s syndrome.
vitreous (Fig. 8.31C) (where it may be floating – lens
nutans; or fixed to retina – lens fixata), sub-retinal Fig. 8.32. Fig. 8.33.
space, subscleral space or extruded out of the globe, Coloboma of the lens. Lenticonus anterior.
partially or completely.
Clinical features of posterior dislocation. These
include: deep anterior chamber, aphakia in pupillary
area, and iridodonesis. Ophthalmoscopic examination
reveals lens in the vitreous cavity.

Clinical features of anterior dislocation are deep
anterior chamber and presence of lens in the anterior
chamber. Clear lens looks like an oil drop in the
aqueous.
Complications associated with dislocated lens are
uveitis and secondary glaucoma.
Management. A lens dislocated in the anterior
chamber and that incarcerated in the pupil should be
removed as early as possible. A dislocated lens from
the vitreous cavity should be removed only if it is
causing uveitis or glaucoma. From the vitreous cavity
lens can be removed after total vitrectomy, either with
the help of an insulated vitreous cryoprobe or by
aspiration facility of vitrectomy probe (only soft
cataract).

99CHAPTER Glaucoma
ANATOMY AND PHYSIOLOGY PRIMARY OPEN-ANGLE GLAUCOMA AND
Applied anatomy RELATED CONDITIONS
Applied physiology
Primary open-angle glaucoma
GENERAL CONSIDERATIONS Ocular hypertension
Definition and classification of glaucoma Normal tension glaucoma
Pathogenesis of glaucomatous ocular
damage PRIMARY ANGLE-CLOSURE GLAUCOMA
Latent glaucoma
CONGENITAL GLAUCOMAS Intermittent glaucoma
Terminology Acute congestive glaucoma
Primary developmental glaucoma Postcongestive angle-closure glaucoma
Developmental glaucoma with Chronic closed angle glaucoma
associated anomalies Absolute glaucoma

SECONDARY GLAUCOMAS
SURGICAL PROCEDURES FOR GLAUCOMA

ANATOMY AND PHYSIOLOGY be visualised by gonioscopic examination (see page
546).
APPLIED ANATOMY Gonioscopic grading of the angle width. Various
Pathophysiology of glaucoma revolves around the systems have been suggested to grade angle width.
aqueous humour dynamics. The principal ocular The most commonly used Shaffer’s system of grading
structures concerned with it are ciliary body, angle of the angle is given in Table 9.1 and is shown in
anterior chamber and the aqueous outflow system. Fig. 9.2.

Ciliary body

It is the seat of aqueous production. Applied aspects
of its anatomy have been described on page .........

Angle of anterior chamber Fig. 9.1. Section of the anterior ocular structures showing
region of the anterior chamber.
Angle of anterior chamber plays an important role in
the process of aqueous drainage. It is formed by root
of iris, anterior-most part of ciliary body, scleral spur,
trabecular meshwork and Schwalbe’s line (prominent
end of Descemet’s membrane of cornea) (Fig. 9.1).
The angle width varies in different individuals and
plays a vital role in the pathomechanism of different
types of glaucoma. Clinically the angle structures can

206 Comprehensive OPHTHALMOLOGY

Table 9.1. Shaffer’s system of grading the angle width

Grade Angle width Configuration Chances of closure Structures visible on gonioscopy

IV 35-45o Wide open Nil SL, TM, SS, CBB
III 20-35o Open angle Nil SL, TM, SS
II 20o Moderately narrow Possible SL, TM
I 10o Very narrow High SL only
0 0o Closed Closed None of the angle structures visible

SL = Schwalbe’s line, TM = Trabecular meshwork, SS = Scleral spur, CBB = Ciliary body band

Fig. 9.2. Diagrammatic depiction of various angle structures (SL, Schwalbe's line; TM, trabecular meshwork; SS, scleral
spur; CBB, ciliary body band; ROI, root of iris) as seen in different grades of angle width (Schaffer's grading

system): A, Gonioscopic view; B, Configuration of the angle in cross section of the anterior chamber.

Aqueous outflow system Fig. 9.3.A The aqueous outflow system.

It includes the trabecular meshwork, Schlemm’s canal, either side by endothelium. This narrow part of
collector channels, aqueous veins and the episcleral trabeculum connects the corneoscleral meshwork
veins (Fig. 9.3A). with Schlemm’s canal. In fact the outer endothelial
layer of juxtacanalicular meshwork comprises the
1. Trabecular meshwork.It is a sieve-like structure inner wall of Schlemm’s canal. This part of
through which aqueous humour leaves the eye. It trabecular meshwork mainly offers the normal
consists of three portions. resistance to aqueous outflow.
i. Uveal meshwork. It is the innermost part of

trabecular meshwork and extends from the iris
root and ciliary body to the Schwalbe's line. The
arrangement of uveal trabecular bands create
openings of about 25 m to 75 m.
ii. Corneoscleral meshwork. It forms the larger
middle portion which extends from the scleral
spur to the lateral wall of the scleral sulcus. It
consists of sheets of trabeculae that are perforated
by elliptical openings which are smaller than
those in the uveal meshwork (5 µ-50 µ).

iii Juxtacanalicular (endothelial) meshwork. It
forms the outermost portion of meshwork and
consists of a layer of connective tissue lined on

GLAUCOMA 207

2. Schlemm’s canal. This is an endothelial lined oval acid (7.4), inositol (0.1), Na+ (144), K+ (4.5), Cl—
channel present circumferentially in the scleral sulcus. (10), and HCO3— (34).
The endothelial cells of its inner wall are irregular, Oxygen is present in aqueous in dissolved state.
spindle-shaped and contain giant vacuoles. The outer Note: Thus, composition of aqueous is similar to
wall of the canal is lined by smooth flat cells and plasma except that it has:
contains the openings of collector channels. High concentrations of ascorbate, pyruvate and
3. Collector channels. These, also called intra- lactate; and
scleral aqueous vessels, are about 25-35 in number Low concentration of protein, urea and glucose.
and leave the Schlemm’s canal at oblique angles to
terminate into episcleral veins in a laminated fashion. Aqueous humour: anterior chamber versus posterior
These intrascleral aqueous vessels can be divided chamber. The composition of aqeuous humour in
into two systems (Fig. 9.3A). The larger vessels anterior chamber differs from that of the aqueous
(aqueous veins) run a short intrascleral course and humour in posterior chamber because of metabolic
terminate directly into episcleral veins (direct system). interchange. The main differences are :
Many smaller collector channels form an intrascleral
plexus before eventually going into episcleral veins HCO3— in posterior chamber aqueous is higher
(indirect system). than in the anterior chamber.
Cl— concentration in posterior chamber is lower
APPLIED PHYSIOLOGY than in the anterior chamber.
Ascorbate concentration of posterior aqueous is
The physiological processes concerned with the slightly higher than that of anterior chamber
dynamics of aqueous humour are its production, aqueous.
drainage and maintenance of intraocular pressure. Production. Aqueous humour is derived from plasma
within the capillary network of ciliary processes. The
Aqueous humour and its production normal aqueous production rate is 2.3 µl/min. The
three mechanisms diffusion, ultrafiltration and
Volume. The aqueous humour is a clear watery fluid secretion (active transport) play a part in its
filling the anterior chamber (0.25 ml) and posterior production at different levels. The steps involved in
chamber (0.06 ml) of the eyeball. the process of production are summarized below:
Functions of aqueous humour are: 1. Ultrafiltration. First of all, by ultrafiltration, most
of the plasma substances pass out from the
It maintains a proper intraocular pressure. capillary wall, loose connective tissue and
It plays an important metabolic role by providing pigment epithelium of the ciliary processes. Thus,
substrates and by removing metabolites from the the plasma filtrate accumulates behind the non-
avascular cornea and lens. pigment epithelium of ciliary processes.
It maintains optical transparency. 2. Secretion. The tight junctions between the cells
It takes the place of lymph that is absent within of the non-pigment epithelium create part of blood
the eyeball. aqueous barrier. Certain substances are actively
Refractive index of aqueous humour is 1.336. transported (secreted) across this barrier into the
Composition. Constituents of normal aqueous posterior chamber. The active transport is brought
humour are on :. about by Na+-K+ activated ATPase pump and
Water 99.9 and solids 0.1% which include : carbonic anhydrase enzyme system. Substances
Proteins (colloid content). Because of blood that are actively transported include sodium,
aqueous barrier the protein content of aqueous chlorides, potassium, ascorbic acid, amino acids
humour (5-16 mg%) is much less than that of and bicarbonates.
plasma (6-7 gm%). However, in inflammation of 3. Diffusion. Active transport of these substances
uvea (iridocyclitis) the blood-aqueous barrier is across the non-pigmented ciliary epithelium results
broken and the protein content of aqueous is in an osmotic gradient leading to the movement
increased (plasmoid aqueous). of other plasma constituents into the posterior
Amino acid constituent of aqueous humour is chamber by ultrafiltration and diffusion. Sodium
about 5 mg/kg water. is primarily responsible for the movement of water
into the posterior chamber.
Non-colloid constituents in millimols /kg water
are glucose (6.0), urea (7), ascorbate (0.9), lactic

208 Comprehensive OPHTHALMOLOGY

Control of aqueous formation. The diurnal variation Maintenance of intraocular pressure
in intraocular pressure certainly indicates that some The intraocular pressure (IOP) refers to the pressure
endogenous factors do influence the aqueous exerted by intraocular fluids on the coats of the
formation. The exact role of such factors is yet to be eyeball. The normal IOP varies between 10 and 21 mm
clearly understood. Vasopressin and adenyl-cyclase of Hg (mean 16 ± 2.5 mm of Hg). The normal level of
have been described to affect aqueous formation by IOP is essentially maintained by a dynamic
influencing active transport of sodium. equilibrium between the formation and outflow of the
aqueous humour. Various factors influencing
Ultrafiltration and diffusion, the passive intraocular pressure can be grouped as under:
mechanisms of aqueous formation, are dependent on (A) Local factors
the level of blood pressure in the ciliary capillaries, 1. Rate of aqueous formation influences IOP levels.
the plasma osmotic pressure and the level of
intraocular pressure. The aqueous formation in turn depends upon
many factors such as permeability of ciliary
Drainage of aqueous humour capillaries and osmotic pressure of the blood.
Aqueous humour flows from the posterior chamber 2. Resistance to aqueous outflow (drainage). From
into the anterior chamber through the pupil against clinical point of view, this is the most important
slight physiologic resistance. From the anterior factor. Most of the resistance to aqueous outflow
chamber the aqueous is drained out by two routes is at the level of trabecular meshwork.
(Fig. 9.3B): 3. Increased episcleral venous pressure may result
in rise of IOP. The Valsalva manoeuvre causes
1. Trabecular (conventional) outflow. Trabecular temporary increase in episcleral venous pressure
meshwork is the main outlet for aqueous from the and rise in IOP.
anterior chamber. Approximately 90 percent of the
total aqueous is drained out via this route. Fig. 9.3.B Flow chart depicting drainage of aqueous
humour
Free flow of aqueous occurs from trabecular
meshwork up to inner wall of Schlemm's canal which
appears to provide some resistance to outflow.
Mechanism of aqueous transport across inner wall
of Schlemm’s canal. It is partially understood.
Vacuolation theory is the most accepted view.
According to it, transcellular spaces exist in the
endothelial cells forming inner wall of Schlemm's
canal. These open as a system of vacuoles and pores,
primarily in response to pressure, and transport the
aqueous from the juxtacanalicular connective tissue
to Schlemm’s canal (Fig. 9.4).

From Schlemm's canal the aqueous is transported
via 25-35 external collector channels into the episcleral
veins by direct and indirect systems (Fig. 9.3A). A
pressure gradient between intraocular pressure and
intrascleral venous pressure (about 10 mm of Hg) is
responsible for unidirectional flow of aqueous.
2. Uveoscleral (unconventional) outlow. It is
responsible for about 10 percent of the total aqueous
outflow. Aqueous passes across the ciliary body into
the suprachoroidal space and is drained by the
venous circulation in the ciliary body, choroid and
sclera.

The drainage of aqueous humour is summarized in
the flowchart (Fig. 9.3B).

GLAUCOMA 209

Fig. 9.4. Vacuolation theory of aqueous transport across the inner wall of the Schlemm's canal: 1. Non-vacuolated stage; 2.
Stage of early infolding of basal surface of the endothelial cell; 3. Stage of macrovacuolar structure formation; 4. Stage of
vacuolar transcellular channel formation;5.Stage of occlusion of the basal infolding.

210 Comprehensive OPHTHALMOLOGY

4. Dilatation of pupil in patients with narrow not invariably with raised intraocular pressure (IOP).
anterior chamber angle may cause rise of IOP Thus, IOP is the most common risk factor but not the
owing to a relative obstruction of the aqeuous only risk factor for development of glaucoma.
drainage by the iris. Consequently the term ‘ocular hypertension’ is used
for cases having constantly raised IOP without any
(B) General factors associated glaucomatous damage. Conversely, the
1. Heredity. It influences IOP, possibly by term normal or low tension glaucoma (NTG/LTG) is
suggested for the typical cupping of the disc and/or
multifactorial modes. visual field defects associated with a normal or low
2. Age. The mean IOP increases after the age of 40 IOP.

years, possibly due to reduced facility of aqueous Classification
outflow. Clinico-etiologically glaucoma may be classified as
3. Sex. IOP is equal between the sexes in ages 20- follows:
40 years. In older age groups increase in mean (A) Congenital and developmental glaucomas
IOP with age is greater in females. 1. Primary congenital glaucoma (without associated
4. Diurnal variation of IOP. Usually, there is a
tendency of higher IOP in the morning and lower anomalies).
in the evening (Fig. 9.7). This has been related to 2. Developmental glaucoma (with associated
diurnal variation in the levels of plasma cortisol.
Normal eyes have a smaller fluctuation (< 5 mm anomalies).
of Hg) than glaucomatous eyes (> 8 mm of Hg). (B) Primary adult glaucomas
5. Postural variations. IOP increases when 1. Primary open angle glaucomas (POAG)
changing from the sitting to the supine position. 2. Primary angle closure glaucoma (PACG)
6. Blood pressure. As such it does not have long- 3. Primary mixed mechanism glaucoma
term effect on IOP. However, prevalence of (C) Secondary glaucomas
glaucoma is marginally more in hypertensives
than the normotensives. PATHOGENESIS OF GLAUCOMATOUS OCULAR
7. Osmotic pressure of blood. An increase in plasma DAMAGE
osmolarity (as occurs after intravenous mannitol, oral
glycerol or in patients with uraemia) is associated As mentioned in definition, all glaucomas (classified
with a fall in IOP, while a reduction in plasma above and described later) are characterized by a
osmolarity (as occurs with water drinking progressive optic neuropathy. It has now been
provocative tests) is associated with a rise in IOP. recognized that progressive optic neuropathy results
8. General anaesthetics and many other drugs also from the death of retinal ganglion cells (RGCs) in a
influence IOP e.g., alcohol lowers IOP, tobacco typical pattern which results in characteristic optic
smoking, caffeine and steroids may cause rise in disc appearance and specific visual field defects.
IOP. In addition there are many antiglaucoma
drugs which lower IOP. Pathogenesis of retinal ganglion cell death

GENERAL CONSIDERATIONS Retinal ganglion cell (RGC) death is initiated when
some pathologic event blocks the transport of growth
DEFINITION AND CLASSIFICATION OF factors (neurotrophins) from the brain to the RGCs.
GLAUCOMA The blockage of these neurotrophins initiate a
damaging cascade, and the cell is unable to maintain
Definition its normal function. The RGCs losing their ability to
maintain normal function undergo apoptosis and also
Glaucoma is not a single disease process but a group trigger apoptosis of adjacent cells. Apoptosis is a
of disorders characterized by a progressive optic genetically controlled cell suicide programme whereby
neuropathy resulting in a characterstic appearance irreversibaly damaged cells die, and are subsequently
of the optic disc and a specific pattern of irreversible engulfed by neighbouring cells, without eliciting any
visual field defects that are associated frequently but inflammatory response.

GLAUCOMA 211

Retinal ganglion cell death is, of course, associated B. Secondary insults (Excitotoxicity theory)
with loss of retinal nerve fibres. As the loss of nerve Neuronal degeneration is believed to be driven by
fibres extends beyond the normal physiological toxic factors such as glutamate (excitatory toxin),
overlap of functional zones. The characteristic optic oxygen free radicals, or nitric oxide which are released
disc changes and specific visual field defects become when RGCs undergo death due to primary insults. In
apparent over the time. this way the secondary insult leads to continued
damage mediated apoptosis, even after the primary
Etiological factors insult has been controlled.

Factors involved in the etiology of retinal ganglion CONGENITAL / DEVELOPMENTAL
cell death and thus in the etiology of glaucomatous GLAUCOMAS
optic neuropathy can be grouped as below:
TERMINOLOGY
A. Primary insults The congenital glaucomas are a group of diverse
disorders in which abnormal high intraocular pressure
1. Raised intraocular pressure (Mechanical theory). results due to developmental abnormalities of the
Raised intraocular pressure causes mechanical stretch angle of anterior chamber obstructing the drainage
on the lamina cribrosa leading to axonal deformation of aqueous humour. Sometimes glaucoma may not
and ischaemia by altering capillary blood flow. As a occur until several years after birth; therefore, the
result of this, neurotrophins (growth factors) are not term developmental glaucoma is preferred to describe
able to reach the retinal ganglion cell bodies in such disorders.
sufficient amount needed for their survival.
2. Pressure independent factors (Vascular Types
insufficiency theory). Factors affecting vascular 1. Primary developmental/congenital glaucoma.
perfusion of optic nerve head in the absence of raised 2. Developmental glaucoma with associated ocular
IOP have been implicated in the glaucomatous optic
neuropathy in patients with normal tension glaucoma anomalies.
(NTG). However, these may be the additional factors
in cases of raised IOP as well. These factors include: PRIMARY DEVELOPMENTAL/CONGENITAL
i. Failure of autoregulatory mechanism of blood GLAUCOMA

flow. The retina and optic nerve share a peculiar It refers to abnormally high IOP which results due to
mechanism of autoregulation of blood flow with developmental anomaly of the angle of the anterior
rest of the central nervous system. Once the chamber, not associated with any other ocular or
autoregulatory mechanisms are compromised, systemic anomaly. Depending upon the age of onset
blood flow may not be adequate beyond some the developmental glaucomas are termed as follows:
critical range of IOP (which may be raised or in
normal range). 1. True congenital glaucoma is labelled when IOP is
ii. Vasospasm is another mechanism affecting raised during intrauterine life and child is born with
vascular perfusion of optic nerve head. This ocular enlargement. It occurs in about 40 percent of
hypothesis gets credence from the convincing cases.
association between NTG and vasospastic
disorders (migranous headache and Raynaud's 2. Infantile glaucoma is labelled when the disease
phenomenon). manifests prior to the child's third birthday. It occurs
iii. Systemic hypotension particularly nocturnal dips in about 50 percent of cases.
in patients with night time administration of
antihypertensive drugs has been implicated for 3. Juvenile glaucoma is labelled in the rest 10 percent
low vascular perfusion of optic nerve head of cases who develop pressure rise between 3-16
resulting in NTG. years of life.
iv. Other factors such as acute blood loss and
abnormal coagulability profile have also been
associated with NTG.

212 Comprehensive OPHTHALMOLOGY

When the disease manifests prior to age of 3 years, i. Corneal oedema. It is frequently the first sign
the eyeball enlarges and so the term‘buphthalmos’ which arouses suspicion. At first it is epithelial,
(bull-like eyes) is used. As it results due to retention but later there is stromal involvement and
of aqueous humour (watery solution), the term permanent opacities may occur.
‘hydrophthalmos, has also been suggested.
ii. Corneal enlargement. It occurs along with
Prevalence and genetic pattern enlargement of globe-buphthalmos (Fig. 9.5),
especially when the onset is before the age of 3
Most cases are sporadic. About 10 percent cases years. Normal infant cornea measures 10.5 mm. A
exhibit an autosomal recessive inheritance with diameter of more than 13 mm confirms
incomplete peneterance. enlargement. Prognosis is usually poor in infants
Although sex linkage is not common in with corneal diameter of more than 16 mm.
inheritance, over 65 percent of the patients are
boys. iii. Tears and breaks in Descemet’s membrane
The disease is bilateral in 75 percent cases, though (Haab’s striae). These occur because Descemet’s
the involvement may be asymmetric. membrane is less elastic than the corneal stroma.
The disease affects only 1 child in 10,000 births. Tears are usually peripheral and concentric with
the limbus.
Pathogenesis
3. Sclera becomes thin and appears blue due to
Maldevelopment of trabeculum including the underlying uveal tissue.
iridotrabecular junction (trabeculodysgenesis) is 4. Anterior chamber becomes deep.
responsible for impaired aqueous outflow resulting 5. Iris may show iridodonesis and atrophic patches
in raised IOP. In primary congenital glaucoma the in late stage.
trabeculodysgenesis is not associated with any other 6. Lens becomes flat due to stretching of zonules and
major ocular anomalies. Clinically, trabeculodys- may even subluxate.
genesis is characterized by absence of the angle 7. Optic disc may show variable cupping and atrophy
recess with iris having a flat or concave direct especially after third year.
insertion into the surface of trabeculum as follows: 8. IOP is raised which is neither marked nor acute.
9. Axial myopia may occur because of increase in
Flat iris insertion is more common than the axial length which may give rise to anisometropic
concave iris insertion. In it the iris inserts flatly amblyopia.
and abruptly into the thickened trabeculum either
at or anterior to scleral spur (more often) or Examination (Evaluation)
posterior to scleral spur. It is often possible to A complete examination under general anaesthesia
visualize a portion of ciliary body and scleral should be performed on each child suspected of
spur. having congenital glaucoma. The examination should
Concave iris insertion is less common. In it the include following:
superficial iris tissue sweeps over the
iridotrabecular junction and the trabeculum and Fig. 9.5. A child with congenital glaucoma.
thus obscures the scleral spur and ciliary body.

Clinical features
1. Photophobia, blepharospasm, lacrimation and
eye rubbing often occur together. These are thought
to be caused by irritation of corneal nerves, which
occurs as a result of the elevated IOP. Photophobia is
usually the initial sign, but is not enough by itself to
arouse suspicion in most cases.
2. Corneal signs. Corneal signs include its oedema,
enlargement and Descemet’s breaks.

GLAUCOMA 213

1. Measurement of IOP with Schiotz or preferably Fig. 9.6. Technique of goniotomy : A, showing position of
hand held Perkin’s applanation tonometer since goniotomy knife in the angle under direct visualization; B,
scleral rigidity is very low in children.
showing procedure of sweeping the knife in the angle.
2. Measurement of corneal diameter by callipers.
is then withdrawn. Although the procedure may have
3. Ophthalmoscopy to evalute optic disc. to be repeated, the eventual success rate is about 85
percent.
4. Gonioscopic examination of angle of anterior
chamber reveals trabeculodysgenesis with either 2. Trabeculotomy. This is useful when corneal
flat or concave iris insertion as described in clouding prevents visualization of the angle or in cases
pathogenesis. where goniotomy has failed. In this, canal of Schlemm
is exposed at about 12 O’clock position by a vertical
Differential diagnosis scleral incision after making a conjunctival flap and
It is to be considered for different presenting signs partial thickness scleral flap. The lower prong of
as follows: Harm’s trabeculotome is passed along the Schlemm’s
canal on one side and the upper prong is used as a
1. Cloudy cornea. In unilateral cases the commonest guide (Fig. 9.7). Then the trabeculotome is rotated so
cause is trauma with rupture of Descemet’s as to break the inner wall over one quarter of the
membrane (forceps injury). In bilateral cases canal. This is then repeated on the other side. The
causes may be trauma, mucopolysaccharidosis, main difficulty in this operation is localization of the
interstitial keratitis and corneal endothelial Schlemm's canal.
dystrophy.
3. Combined trabeculotomy and trabeculectomy is
2. Large cornea due to buphthalmos should be now-a-days the preferred surgery with better results.
differentiated from megalocornea.

3. Lacrimation in an infant is usually considered to
be due to congenital nasolacrimal duct blockage
and thus early diagnosis of congenital glaucoma
may be missed.

4. Photophobia may be due to keratitis or uveitis.

5. Raised IOP in infants may also be associated
with retinoblastoma, retinopathy of prematurity,
persistent primary hyperplastic vitreous, traumatic
glaucoma and secondary congenital glaucoma
seen in rubella, aniridia and Sturge-Weber
syndrome.

Treatment
Treatment of congenital glaucoma is primarily
surgical. However, IOP must be lowered by use of
hyperosmotic agents, acetazolamide and beta-
blockers till surgery is taken up. Miotics are of no
use in such cases.

Surgical procedures for congenital glaucoma
1. Goniotomy (Fig. 9.6). In this procedure a Barkan's
goniotomy knife is passed through the limbus on the
temporal side. Under gonioscopic control the knife is
passed across the anterior chamber to the nasal part
of the angle. An incision is made in the angle
approximately midway between root of the iris and
Schwalbe's ring through approximately 75°. The knife

214 Comprehensive OPHTHALMOLOGY

PRIMARY OPEN ANGLE
GLAUCOMA AND RELATED

CONDITIONS

PRIMARY OPEN ANGLE GLAUCOMA

As the name implies, it is a type of primary glaucoma,
where there is no obvious systemic or ocular cause
of rise in the intraocular pressure. It occurs in eyes
with open angle of the anterior chamber. Primary open
angle glaucoma (POAG) also known as chronic simple
glaucoma of adult onset and is typically characterised
by slowly progressive raised intraocular pressure
(>21 mmHg recorded on at least a few occasions)
associated with characteristic optic disc cupping and
specific visual field defects.

Fig. 9.7. Technique of trabeculotomy. ETIOPATHOGENESIS

DEVELOPMENTAL GLAUCOMAS WITH Etiopathogenesis of POAG is not known exactly.
ASSOCIATED ANOMALIES Some of the known facts are as follows:

A wide variety of systemic and/or ocular anomalies (A) Predisposing and risk factors. These include
have an associated raised IOP, usually due to the following:
developmental defects of the anterior chamber angle. 1. Heredity. POAG has a polygenic inheritance. The
Some of the associations are as follows:
approximate risk of getting disease is 10% in the
1. Glaucoma associated with iridocorneal siblings, and 4% in the offspring of patients with
dysgenesis. These include: posterior embryotoxon POAG.
characterised by a prominent Schwalbe’s ring 2. Age. The risk increases with increasing age. The
(Axenfeld anomaly), Rieger anomaly, Rieger POAG is more commonly seen in elderly between
syndrome, Peter’s anomaly and combined Rieger 5th and 7th decades.
syndrome and Peter’s anomaly. 3. Race. POAG is significantly more common,
develops earlier and is more severe in black
2. Glaucoma associated with aniridia (50% cases). people than in white.
4. Myopes are more predisposed than the normals.
3. Glaucoma associated with ectopia lentis 5. Diabetics have a higher prevalence of POAG
syndromes, which include Marfan’s syndrome, than non-diabetics.
Weil-Marchesani syndrome and homocystinuria. 6. Cigarette smoking is also thought to increase its
risk.
4. Glaucoma associated with phakomatosis is seen 7. High blood pressure is not the cause of rise in
in Sturge-Weber syndrome ( 50% cases) and Von IOP, however the prevalence of POAG is more in
Recklinghausen’s neurofibromatosis (25% cases). hypertensives than the normotensives.
8. Thyrotoxicosis is also not the cause of rise in
5. Miscellaneous conditions. Lowe’s syndrome IOP, but the prevalence of POAG is more in
(oculo-cerebro-renal syndrome), naevus of Ota, patients suffering from Graves’ ophthalmic disease
nanophthalmos, congenital ectropion uveae, than the normals.
congenital microcornea and rubella syndrome.
(B) Pathogenesis of rise in IOP. It is certain that rise
in IOP occurs due to decrease in the aqueous outflow
facility due to increased resistance to aqueous

GLAUCOMA 215

outflow caused by age-related thickening and over 5 mm Hg (Schiotz) is suspicious and over 8 mm
sclerosis of the trabeculae and an absence of giant of Hg is diagnostic of glaucoma. In later stages, IOP
vacuoles in the cells lining the canal of Schlemm. is permanently raised above 21 mm of Hg and ranges
However, the cause of these changes is uncertain. between 30 and 45 mm of Hg.

(C) Corticosteroid responsiveness. Patients with
POAG and their offspring and sibilings are more likely
to respond to six weeks topical steroid therapy with a
significant rise of IOP.

INCIDENCE OF POAG

It varies in different populations. In general, it affects
about 1 in 100 of the general population (of either
sex) above the age of 40 years. It forms about one-
third cases of all glaucomas.

CLINICAL FEATURES Fig. 9.8. Patterns of diurnal variations of IOP: A, normal
slight morning rise; B, morning rise seen in 20% cases of
Symptoms POAG; C, afternoon rise seen in 25% cases of POAG;

1. The disease is insidious and usually D, biphasic variation seen in 55% cases of POAG.
asymptomatic, until it has caused a significant
loss of visual field. Therefore, periodic eye
examination is required after middle age.

2. Patients may experience mild headache and
eyeache.

3. Occasionally, an observant patient may notice a
defect in the visual field.

4. Reading and close work often present increasing
difficulties owing to accommodative failure due
to constant pressure on the ciliary muscle and its
nerve supply. Therefore, patients usually complain
of frequent changes in presbyopic glasses.

5. Patients develop delayed dark adaptation, a
disability which becomes increasingly disturbing
in the later stages.

Signs

I. Anterior segment signs. Ocular examination
including slit-lamp biomicroscopy may reveal normal
anterior segment. In late stages pupil reflex becomes
sluggish and cornea may show slight haze.
II. Intraocular pressure changes. In the initial stages
the IOP may not be raised permanently, but there is
an exaggeration of the normal diurnal variation.
Therefore, repeated observations of IOP (every 3-4
hour), for 24 hours is required during this stage
(Diurnal variation test). In most patients IOP falls
during the evening, contrary to what happens in
closed angle glaucoma. Patterns of diurnal variation
of IOP are shown in Fig. 9.8. A variation in IOP of

216 Comprehensive OPHTHALMOLOGY

III. Optic disc changes. Optic disc changes, usually 2. Thinning of neuroretinal rim which occurs in
observed on routine fundus examination, provide an advanced cases is seen as a crescentric shadow
important clue for suspecting POAG. These are adjacent to the disc margin.
typically progressive, asymmetric and present a
variety of characteristic clinical patterns. It is essential, 3. Nasal shifting of retinal vessels which have the
therefore, to record the appearance of the nerve head appearance of being broken off at the margin is
in such a way that will accurately reveal subtle an important sign (Bayonetting sign). When the
glaucomatous changes over the course of follow-up edges overhang, the course of the vessels as
evaluation. they climb the sides of the cup is hidden.
Examination techniques. Careful assessment of disc
changes can be made by direct ophthalmoscopy, slit- 4. Pulsations of the retinal arterioles may be seen
lamp biomicroscopy using a + 90D lens, Hruby lens at the disc margin (a pathognomic sign of
or Goldmann contact lens and indirect glaucoma), when IOP is very high.
ophthalmoscopy.
The recording and documentation techniques 5. Lamellar dot sign the pores in the lamina cribrosa
include serial drawings, photography and are slit-shaped and are visible up to the margin
photogrammetry. Confocal scanning laser topography of the disc.
(CSLT) i.e., Heidelberg retinal tomograph (HRT) is an
accurate and sensitive method for this purpose. Other (c) Glaucomatous optic atrophy. As the damage
advanced imaging techniques include optical progresses, all the neural tissue of the disc is
coherence tomography (OCT) and scanning laser destroyed and the optic nerve head appears white
polarimetry i.e., Nerve fibre analyser (NFA). and deeply excavated (Figs. 9.10 C&D).
Pathophysiology of disc changes. Both mechanical
Glaucomatous changes in the optic disc can be and vascular factors play a role in the cupping of the
described as early changes, advanced changes and disc.
glaucomatous optic atrophy. Figures 9.9A & B show
normal disc configuration. Mechanical effect of raised IOP forces the lamina
cribrosa backwards and squeezes the nerve fibres
(a) Early glaucomatous changes (Figs. 9.9C&D) within its meshes to disturb axoplasmic flow.
should be suspected to exist if fundus examination Vascular factors contribute in ischaemic atrophy
reveals one or more of the following signs: of the nerve fibres without corresponding increase
1. Vertically oval cup due to selective loss of of supporting glial tissue. As a result, large
caverns or lacunae are formed (cavernous optic
neural rim tissue in the inferior and superior atrophy).
poles. IV. Visual field defects. Visual field defects usually
2. Asymmetry of the cups. A difference of more than run parallel to the changes at the optic nerve head
0.2 between two eyes is significant. and continue to progress if IOP is not controlled.
3. Large cup i.e., 0.6 or more (normal cup size is 0.3 These can be described as early and late field defects.
to 0.4) may occur due to concentric expansion. Anatomical basis of field defects. For better
4. Splinter haemorrhages present on or near the understanding of the actual field defects, it is
optic disc margin. mandatory to have a knowledge of their anatomical
5. Pallor areas on the disc. basis.
6. Atrophy of retinal nerve fibre layer which may
be seen with red free light. (A) Distribution of retinal nerve fibres (Fig. 9.11).
1. Fibres from nasal half of the retina come directly
(b) Advanced glaucomatous changes in the optic
disc (Figs. 9.10A&B): to the optic disc as superior and inferior radiating
1. Marked cupping (cup size 0.7 to 0.9), excavation fibres (srf and irf).
2. Those from the macular area come horizontally as
may even reach the disc margin, the sides are papillomacular bundle (pmb).
steep and not shelving (c.f. deep physiological 3. Fibres from the temporal retina arch above and
cup). below the macula and papillomacular bundle as
superior and inferior arcuate fibres with a
horizontal raphe in between (saf and iaf).

GLAUCOMA 217

C
A

BD

Fig. 9.9. Normal optic disc (A, Diagrammatic depiction; B, Fundus photograph) and optic disc showing early glaucoma-
tous changes (C, Diagrammatic depiction; D, Fundus photograph).

(B) Arrangement of nerve fibres within optic nerve The arcuate nerve fibres occupy the superior and
head (Fig. 9.12): Those from the peripheral part of the inferior temporal portions of optic nerve head and are
retina lie deep in the retina but occupy the most most sensitive to glaucomatous damage; accounting
peripheral (superficial) part of the optic disc. While for the early loss in the corresponding regions of the
fibres originating closer to the nerve head lie visual field. Macular fibres are most resistant to the
superficially in the retina and occupy a more central glaucomatous damage and explain the retention of
(deep) portion of the disc. the central vision till end.

218 Comprehensive OPHTHALMOLOGY

AC

BD

Fig. 9.10. Optic disc showing advanced glaucomatous changes (A, diagramatic depiction; B, fundus photograph) and
glaucomotous optic atrophy (C, diagramatic depiction; D, fundus photograph).

Progression of field defects. Visual field defects in glaucoma. However, it is of limited diagnostic
glaucoma are initially observed in Bjerrum’s area (10- value, as it may also occur in many other
25 degree from fixation) and correlate with optic disc conditions.
changes. The natural history of the progressive 2. Baring of blind spot. It is also considered to be an
glaucomatous field loss, more or less, takes the early glaucomatous change, but is very non-specific
following sequence: and thus of limited diagnostic value. Baring of the
1. Isopter contraction. It refers to mild generalised blind spot means exclusion of the blind spot from
the central field due to inward curve of the outer
constriction of central as well as peripheral field. boundary of 30° central field (Fig. 9.13A).
It is the earliest visual field defect occurring in

GLAUCOMA 219

Fig. 9.11. Distribution of retinal nerve fibres.

Fig. 9.12. Arrangement of nerve fibres within
optic nerve head.

3. Small wing-shaped paracentral scotoma (Fig. Fig. 9.13. Field defects in POAG: A, baring of blind spot; B,
9.13B). It is the earliest clinically significant field superior paracentral scotoma; C, Seidel's scotoma; D,
defect. It may appear either below or above the Bjerru-m's scotoma; E, double arcuate scotoma and
blind spot in Bjerrum's area (an arcuate area Roenne's central nasal step.
extending above and below the blind spot to
between 10o and 20o of fixation point).

4. Seidel’s scotoma.With the passage of time
paracental scotoma joins the blind spot to form
a sickle shaped scotoma known as Seidel’s
scotoma (Fig. 9.13C).

5. Arcuate or Bjerrum’s scotoma. It is formed at a
later stage by the extension of Seidel’s scotoma
in an area either above or below the fixation point
to reach the horizontal line (Fig. 9.13D). Damage
to the adjacent fibres causes a peripheral
breakthrough.

6. Ring or double arcuate scotoma. It develops
when the two arcuate scotomas join together
(Fig. 9.13E).

7. Roenne's central nasal step. It is created when
the two arcuate scotomas run in different arcs
and meet to form a sharp right-angled defect at
the horizontal meridian (Fig. 9.13E).

220 Comprehensive OPHTHALMOLOGY

8. Peripheral field defects. These appear sometimes Note. For proper understanding of Table 9.2,
at an early stage and sometimes only late in the evaluation of the Humphrey single field printout
disease. The peripheral nasal step of Roenne's described on page 485 should be revised.
results from unequal contraction of the peripheral
isopter. Ocular associations
POAG may sometimes be associated with high myopia,
9. Advanced glaucomatous field defects. The visual Fuchs’ endothelial dystrophy, retinitis pigmentosa,
field loss gradually spreads centrally as well as central retinal vein occlusion and primary retinal
peripherally, and eventually only a small island of detachment.
central vision (tubular vision) and an
accompanying temporal island are left. With the INVESTIGATIONS
continued damage, these islands of vision also
progressively diminish in size until the tiny central 1. Tonometry. Applanation tonometry should be
island is totally extinguished. The temporal island preferred over Schiotz tonometry (see page 479).
of the vision is more resistant and is lost in the
end leaving the patient with no light perception. 2. Diurnal variation test is especially useful in
detection of early cases (see page 215).
Diagnosis of glaucoma field defects on HFA single
field printout. Glaucomatous field defects should 3. Gonioscopy. It reveals a wide open angle of
always be interpreted in conjunction with clinical anterior chamber. Its primary importance in POAG
features (IOP and optic disc changes). Further, before is to rule out other forms of glaucoma. For details
final interpretation, the fields must be tested twice, (see page 206 and 546).
as there is often a significant improvement in the field
when plotted second time (because patients become 4. Documentation of optic disc changes is of utmost
more familiar with the machine and test process). importance (see page 216).
Criteria to grade glaucomatous field defects. The
criteria to label early, moderate and severe 5. Slit-lamp examination of anterior segment to
glaucomatous field defect from the HFA central 30-2 rule out causes of secondary open angle
test, single printout is depicted in Table 9.2. glaucoma.

6. Perimetry to detect the visual field defects.
7. Nerve fibre layer analyzer (NFLA) is a recently

introduced device which helps in detecting the

Table 9.2: Criteria to diagnose early, moderate and severe glaucomatous field defects from HFA: 30-2- test.

Sr. Parameter Early defects Criteria for glaucomatous field defects Severe defects
no. Moderate defects

1. Mean deviation (MD) <– 6 dB – 6dB – 12 dB > – 12dB
Depressed to the p<5%
2. Corrected pattern Depressed to the p<5% Depressed to the p <5%
standard deviation > 37 (>50%)
(CPSD) < 18 (25%) < 37 (50%)
> 20
3. Pattern deviation plot < 10 < 20
Points depressed Outside normal limits Outside normal limits
below the p < 5% No point < 15dB Outside normal limits
or Both hemifield have
Points depressed One hemifield may have points with sensitivity
below the p < 1% point with sensitivity <15dB
<15dB Any point has 0 dB
4. Glaucoma Hemifield No point has 0 dB
Test (GHT)

5. Sensitivity in central
5 degree

GLAUCOMA 221

glaucomatous damage to the retinal nerve fibres Fig. 9.14. Triad of abnormalities in disc, field and
before the appearance of actual visual field intraocular pressure (IOP) for the diagnosis of glaucoma.
changes and/or optic disc changes.
8. Provocative tests are required in border-line cases. not occur. The management thus requires careful and
The test commonly performed is water drinking regular periodic supervision by an ophthalmologist.
test. Other provocative tests not frequently Therefore, it is important to perform a good baseline
performed include combined water drinking and examination with which future progress can be
tonography, bulbar pressure test, prescoline test compared. The initial data should include: visual
and caffeine test. acuity, slit-lamp examination of anterior segment,
Water drinking test. It is based on the theory that tonometry (preferably with applanation tonometer);
glaucomatous eyes have a greater response to water optic disc evaluation (preferably with fundus
drinking. In it after an 8 hours fast, baseline IOP is photography), gonioscopy and visual field charting.
noted and the patient is asked to drink one litre of
water, following which IOP is noted every 15 min. for American Academy of Ophthalmology (AAO)
1 hour. The maximum rise in IOP occurs in 15-30 min. grades severity of glaucoma damage into mild,
and returns to baseline level after 60 minutes in both moderate and severe (Table 9.3).
normal and the glaucomatous eyes. A rise of 8 mm of
Hg or more is said to be diagnostic of POAG. Table 9.3: Severity of glaucoma damage

DIAGNOSIS Degree Description

Depending upon the level of intraocular pressure Mild Characteristic optic-nerve abnormalities
(IOP), glaucomatous cupping of the optic disc and are consistent with glaucoma but with
the visual field changes (Fig. 9.14) the patients are normal visual field.
assigned to one of the following diagnostic entities:
1. Primary open angle glaucoma (POAG). Moderate Visual-field abnormalities in one hemi-field
Characterstically POAG is labelled when raised IOP and not within 5 degrees of fixation.
(>21 mm of Hg) is associated with definite
glaucomatous optic disc cupping and visual field Severe Visual-field abnormalities in both
changes. hemifields and within 5 degrees of fixation.

However, patients with raised IOP and either typical Source : AAO 2000a
field defects or disc changes are also labelled as
having POAG.
2. Ocular hypertension or glaucoma suspect. Either
of these terms is used when a patient has an IOP
constantly more than 21 mm of Hg but no optic disc
or visual field changes (for details see page 224).
3. Normal tension glaucoma (NTG) or low tension
glaucoma (LTG) is diagnosed when typical
glaucomatous disc cupping with or without visual
field changes is associated with an intraocular
pressure constantly below 21 mm of Hg (For details
see page 224).

MANAGEMENT

General considerations

Baseline evaluation and grading of severity of
glaucoma. The aim of treatment is to lower intraocular
pressure to a level where (further) visual loss does

222 Comprehensive OPHTHALMOLOGY

Therapeutic choices include: IOP by reducing the aqueous secretion due to their
Medical therapy, effect on beta - receptors in the ciliary processes.
Argon or diode laser trabeculoplasty, and Preparations. In terms of effectiveness, there is little
Filteration surgery. difference between various beta-blockers. However,
each offers a slight advantage over the other, which
A. Medical therapy may help in choosing the particular medication as
follows:
The initial therapy of POAG is still medical, with
surgery as the last resort. Timolol maleate (0.25, 0.5% : 1-2 times/day) is
Antiglaucoma drugs available are described in detail most popular as initial therapy. However, it should
on pages 423-427. not be used in patients having associated
bronchial asthma and/or heart blocks.
Basic principles of medical therapy of POAG Betaxolol (0.25% : 2 times/day). Being a selective
beta-1 blocker it is preferred as initial therapy in
1. Identification of target pressure. From the baseline patients with cardiopulmonary problems.
evaluation data a ‘target pressure’ (below which Levobunolol (0.25, 0.5% : 1-2 times/day). Its action
glaucomatous damage is not likely to progress) lasts the longest and so is more reliable for once
should be identified for each patient. The target a day use than timolol.
pressure is identified taking into account the Carteolol (1%: 1-2 times/day). It raises
severity of existing damage, the level of IOP, age, triglycerides and lowers high density lipoproteins
and general health of the patient. Although it is the least. Therefore, it is the best choice in
not possible to predict the safe level of IOP, patients with POAG having associated
however, progression is uncommon if IOP is hyperlipidemias or atherosclerotic cardiovascular
maintained at less than 16 to 18 mm of Hg in disease.
patients having mild to maderate damage. Lower 2. Pilocarpine (1, 2, 4%: 3-4 times/day). It is a very
target pressures (12-14 mmHg) are required in effective drug and had remained as the sheet anchor
patients with severe damage. in the medical management of POAG for a long time.
However, presently it is not being preferred as the
2. Single drug therapy. One topically instilled first drug of choice or even as second choice. It is
antiglaucoma drug should be chosen after due because of the fact that in younger patients it causes
consideration to the patient’s personal and problems due to spasm of accommodation and miosis.
medical factors. If the initial drug chosen is Most, but not all, older patients tolerate pilocarpine
ineffective or intolerable, it should be replaced by very well; however, axial lenticular opacities when
the drug of second choice. present precludes its use in many such patients.
Therefore, presently pilocarpine is being considered
3. Combination therapy. If one drug is not sufficient only as an adjunctive therapy where other
to control IOP then a combination therapy with combinations fail and as second choice in poor
two or more drugs should be tried. patients.
Mechanism of action. Pilocarpine contracts
4. Monitoring of therapy by disc changes and field longitudinal muscle of ciliary body and opens spaces
changes and tonometry is most essential on in trabecular meshwork, thereby mechanically
regular follow-up. In the event of progress of increasing aqueous outflow.
glaucomatous damage the target pressure is reset 3. Latanoprost (0.005%: once daily). It is a
at a lower level. prostaglandin by nature and decreases the IOP by
increasing the uveo-scleral outflow of aqueous.
Treatment regimes. There are no clear-cut Presently, it is being considered the drug of first choice
prescribed treatment regimens for medical therapy of for the treatment of POAG (provided patient can
POAG. However, at present considerations are as afford to buy it). Therefore, it is a very good
follows :

I. Single drug therapy
1. Topical beta-blockers are being recommended as
the first drug of choice for medical therapy of POAG
in poors and average income patients. These lower

GLAUCOMA 223

adjunctive drug to beta-blockers, dorzolamide and Technique and role of ALT in POAG. It has an
even pilocarpine when additional therapy is indicated. additive effect to medical therapy. Its hypotensive
4. Dorzolamide (2%: 2-3 times/day). It is a recently effect is caused by increasing outflow facility,
introduced topical carbonic anhydrase inhibitor which possibly by producing collagen shrinkage on the
lowers IOP by decreasing aqueous secretion. It has inner aspect of the trabecular meshwork and opening
replaced pilocarpine as the second line of drug and the intratrabecular spaces. It has been shown to lower
even as an adjunct drug. IOP by 8-10 mm of Hg in patients on medical therapy
5. Adrenergic drugs. Role in POAG is as follows: and by 12-16 mm in patients who are not receiving
i. Epinephrine hydrochloride (0.5, 1, 2%: 1-2 times/ medical treatment.

day) and dipivefrine hydrochloride (0.1%: 1-2 The treatment regime usually employed consists
times/day). These drugs lower the IOP by of 50 spots on the anterior half of the trabecular
increasing aqueous outflow by stimulating beta meshwork over 180°.
recepters in the aqueous outflow system. These
are characterized by a high allergic reaction rate. Complications. These include transient acute rise of
Their long-term use has also been recognized as IOP, which can be prevented by pretreatment with
a risk factor for failure of filtration glaucoma pilocarpine and/or acetazolamide; and inflammation
surgery. For these reasons, epinephrine which can be lessened by use of topical steroids for
compounds are no longer being used as first line 3-4 days. Less commonly haemorrhage, uveitis,
or second line drug. However, dipivefrine may be peripheral anterior synechiae and reduced
combined with beta-blockers in patients where accommodation may occur.
other drugs are contraindi-cated.
ii. Brimonidine (0.2% : 2 times/day). It is a selective C. Surgical therapy
alpha-2-adrenergic agonist and lowers IOP by
decreasing aqueous production. Because of Indications
increased allergic reactions and tachyphylaxis 1. Uncontrolled glaucoma despite maximal medical
rates it is not considered the drug of first choice
in POAG. It is used as second drug of choice and therapy and laser trabeculoplasty.
also for combination therapy with other drugs.
2. Non-compliance of medical therapy and non-
II. Combination topical therapy availability of ALT.

If one drug is not effective, then a combination of 3. Failure with medical therapy and unsuitable for
two drugs—one drug which decreases aqueous ALT either due to lack of cooperation or inability
production (timolol or other betablocker, or to visualize the trabeculum.
brimonidine or dorzolamide) and other drug which
increase aqueous outflow (latanoprost or brimonidine 4. Eyes with advanced disease i.e., having very
or pilocarpine) may be used. high IOP, advanced cupping and advanced field
loss should be treated with filtration surgery as
III. Role of oral carbonic anhydrase inhibitors in primary line of management.
POAG
5. Recently, some workers are even recommending
Acetazolamide and methazolamide are not surgery as primary line of treatment in all cases.
recommended for long-term use because of their side-
effects. However, these may be added to control IOP Types of surgery
for short term. Surgical treatment of POAG primarily consists of a
fistulizing (filtration) surgery which provides a new
B. Argon or diode laser trabeculoplasty (ALT or channel for aqueous outflow and successfully
DLT) controls the IOP (below 21 mm of Hg).
Trabeculectomy is the most frequently performed
It should be considered in patients where IOP is filtration surgery now-a-days. The details of filtration
uncontrolled despite maximal tolerated medical operations are described on page 237.
therapy. It can also be considered as primary therapy
where there is non-compliance to medical therapy.

224 Comprehensive OPHTHALMOLOGY

OCULAR HYPERTENSION Etiopathogenesis

Ocular hypertension or glaucoma suspect, either of It is believed to result from chronic low vascular
these terms is used when a patient has an IOP perfusion, which makes the optic nerve head
constantly more than 21 mm of Hg but no optic disc susceptible to normal IOP. This view is supported by
or visual field changes. These patients should be following association which are more common in NTG
carefully monitored by an ophthalmologist and than in POAG :
should be treated as cases of POAG in the presence
of high risk factors Raynauld phenomenon i.e., peripheral vascular
High risk factors include: spasm on cooling,
Migraine,
Significant diurnal variation, i.e., a difference of Nocturnal systemic hypotension and overtreated
more than 8 mm of Hg between the lowest and systemic hypertension.
the highest values of IOP. Reduced blood flow velocity in the ophthalmic
Significantly positive water drinking provocative artery (as revealed on transcranial Doppler
test. ultrasonography).
When associated with splinter haemorrhages over
or near the optic disc. Clinical features
IOP constantly more than 28 mm of Hg.
Retinal nerve fibre large defects. As described in definition the clinical features of NTG
Parapapillary changes. (disc changes and visual field defects) are similar to
Central corneal thickness < 555 µm. POAG, but the IOP is consistantaly below 21mm Hg.
Other risk factors include: Other characterstic features of NTG are some
Significant asymmetry in the cup size of the two associations mentioned in the etiopathogenesis.
eyes, i.e., a difference of more than 0.2.
Strong family history of glaucoma. Differential diagnosis
When associated with high myopia, diabetes or
pigmentary changes in the anterior chamber. 1. POAG. In early stages POAG may present with
normal IOP because of a wide diurnal variation.
Treatment Diurnal variation test usually depicts IOP higher than
21 mm of Hg at some hours of the day in patients with
Patients with high-risk factors should be treated POAG.
on the lines of POAG (see page 222). The aim 2. Congentical optic disc anomalies such as large
should be to reduce IOP by 20%. optic disc pits or colobomas may be mistaken for
Patients with no high risk factors should be acquired glaucomatous damage. Acareful examination
annually followed by examination of optic disc, should help in differentiation.
perimetry and record of IOP. Treatment is not
required till glaucomatous damage is documented. Treatment

NORMAL TENSION GLAUCOMA 1. Medical treatment to lower IOP. The aim of the
treatment is to lower IOP by 30% i.e., to achieve IOP
Definition and prevalence levels of about 12-14 mm of Hg. Some important facts
about medical treatment of NTG are:
The term normal tension glaucoma (NTG), also
referred to as low tension glaucoma is labelled when Betaxolol may be considered the drug of choice
typical glaucomatous disc changes with or without because in addition to lowering IOP it also
visual field defects are associated with an intraocular increases optic nerve blood flow.
pressure (IOP) constantly below 21 mm of Hg. Other beta blockers and adrenergic drugs (such
Characterstically the angle of anterior chamber is open as dipiverafrine) should better be avoided (as
on gonioscopy and there is no secondary cause for these cause nocturnal systemic hypotension and
glaucomatous disc changes. NTG is varient of POAG are likely to affect adversely the optic nerve
which accounts for 16% of all cases of POAG and its perfusion).
prevalence above the age of 40 years is 0.2%. Drugs with neuroprotective effect like brimonidine
may be preferred.

GLAUCOMA 225

Prostaglandin analogues, e.g., latanoprost tend Family history. The potential for PACG is
to have a greater ocular hypotensive effect in generally believed to be inherited.
eyes with normal IOP. Race. In caucasians, PACG accounts for about
2. Trabeculectomy may be considered when 6% of all glaucomas and presents in sixth to
progressive field loss occurs despite IOP in lower seventh decade. It is more common in South-East
teens. Asians, Chinese and Eskimos but uncommon in
3. Systemic calcium channel blockers (e.g., Blacks. In Asians it presents in the 5th to 6th
nifedipine) may be useful in patients with confirmed decade and accounts for 50% of primary adult
peripheral vasospasm. glaucomas in this ethnic group.
4. Monitoring of systemic blood pressure should be
done for 24 hours. If nocturnal dip is detected, it may (B) Precipitating factors. In an eye that is
be necessary to avoid night dose of anti-hypertensive predisposed to develop angle closure glaucoma, any
medication. of the following factors may precipitate an attack:

PRIMARY ANGLE-CLOSURE Dim illumination,
GLAUCOMA Emotional stress,
Use of mydriatic drugs like atropine, cyclopento-
It is a type of primary glaucoma (wherein there is no late, tropicamide and phenylephrine.
obvious systemic or ocular cause) in which rise in
intraocular pressure occurs due to blockage of the (C) Mechanism of rise in IOP. The probable
aqueous humour outflow by closure of a narrower sequence of events resulting in rise of IOP in an
angle of the anterior chamber. anatomically predisposed eye is as follows:

ETIOLOGY First of all due to the effect of precipitating factors
there occurs mid dilatation of the pupil which
(A) Predisposing risk factors. These can be divided increases the amount of apposition between iris and
into anatomical and general factors: anteriorly placed lens with a considerable pressure
I. Anatomical factors. Eyes anatomically predisposed resulting in relative pupil block (Fig. 9.15A).
to develop primary angle-closure glaucoma (PACG) Consequently the aqueous collects in the posterior
include: chamber and pushes the peripheral flaccid iris
anteriorly (Iris bombe) (Fig. 9.15B), resulting in
Hypermetropic eyes with shallow anterior appositional angle closure due to iridocorneal
chamber. contact (Fig. 9.15C). Eventually there occurs rise in
Eyes in which iris-lens diaphragm is placed IOP which is transient to begin with. But slowly the
anteriorly. appositional angle closure is converted into synechial
Eyes with narrow angle of anterior chamber, which angle closure (due to formation of peripheral anterior
may be due to: small eyeball, relatively large size synechiae) and an attack of rise in IOP may last long.
of the lens and smaller diameter of the cornea or
bigger size of the ciliary body. In some cases a mechanical occlusion of the angle
Plateau iris configuration. by the iris is sufficient to block the drainage of
II. General factors include: aqueous. For this reason the instillation of atropine
Age. PACG is comparatively more common in 5th in an eye with a narrow angle is dangerous, since it
decade of life. may precipitate an attack of raised IOP.
Sex. Females are more prone to get PACG than
males (male to female ratio is 1:4) CLINICAL PRESENTATION
Type of personality. It is more common in nervous
individuals with unstable vasomotor system. On the basis of clinical presentation, the PACG can
Season. Peak incidence is reported in rainy season. be classified into five different clinical entities.
Previously these were considered progressive stages
of PACG. However, now it has been well established
that the condition does not necessarily progress from
one stage to next in an orderly sequence. In clinical
practice following clinical presentations are seen:

226 Comprehensive OPHTHALMOLOGY

Fig. 9.15. Mechanism of angle closure glaucoma: Clinical features
A, relative pupil block; B, iris bombe formation; Symptoms are absent in this stage.
Signs. In suspected eyes following signs may be
C, appositional angle closure. elicited:
1. Eclipse sign. Eclipse sign, which indicates
Latent primary angle-closure glaucoma (primary
angle-closure glaucoma suspect). decreased axial anterior chamber depth, can be
Subacute (intermittent) primary angle-closure elicited by shining a penlight across the anterior
glaucoma. chamber from the temporal side and noting a
Acute primary angle-closure glaucoma. shadow on the nasal side (Fig. 9.16).
Postcongestive angle-closure glaucoma, 2. Slit-lamp biomicroscopic signs include:
Chronic primary angle-closure glaucoma, and
Absolute glaucoma Decreased axial anterior chamber depth,
Convex shaped iris lens diaphragm, and
Latent primary angle-closure glaucoma Close proximity of the iris to cornea in the
periphery.
The term latent primary angle-closure glaucoma 3. Gonioscopic examination shows very narrow
(Latent PACG) is now used for the eyes which are angle (Shaffer grade I i.e., pigmented trabecular
anatomically predisposed to angle-closure glaucoma. meshwork is not visible without indentation or
Therefore, the preferred term is primary angle-closure manipulation in atleast three of the four
glaucoma suspect i.e., eyes with shallow anterior quadrants) (see page 205 Fig 9.2)
chamber associated with an occludable angle. The 4. Van Herick slit-lamp grading of the angle may
suspect of latent angle-closure glaucoma is made: be used with a fair accuracy when a gonioscope
is not available. Here, the peripheral anterior
On routine slit-lamp examination in patients coming chamber depth (PACD) is compared to the
for some other complaints, and adjacent corneal thickness (CT) and the presumed
In fellow eye of the patients presenting with an angle width is graded as follows (Fig. 9.17):
attack of acute angle-closure glaucoma in one eye. Grade 4 (Wide open angle): PACD = 3/4 to 1 CT
Grade 3 (Mild narrow angle): PACD = ¼ to
½ CT
Grade 2 (Moderate narrow angle): PACD =
¼ CT
Grade 1 ( Extremely narrow angle): PACD
< ¼ CT
Grade 0 (closed angle): PACD = Nil

Fig. 9.16. Estimation of anterior chamber depth by obliq-
ue illumination : A, normal; B, shallow.

GLAUCOMA 227

Clinical course

Eyes with latent primary angle-closure glaucoma,
without treatment, may follow any of the following
clinical courses :

Intraocular pressure may remain normal, or
Subacute or acute angle-closure glaucoma may
occur subsequently, or
Chronic angle-closure glaucoma may develop
without passing through subacute or acute stage.

Diagnosis

Diagnosis is made by:
Clinical signs described above, and positive
provocative tests
Provocative tests. Provocative tests for PACG
suspects have been designed to precipitate closure
of the angle in the ophthalmologist’s office, where it
can be treated promptly.
1. Prone-darkroom test is the most popular and

best physiological provocative test for PACG
suspects. In this test baseline IOP is recorded
and patient is made to lie prone in a darkroom for
one hour. He must remain awake so that pupils
remain dilated. After 1 hour, the IOP is again
measured. An increase in IOP of more than 8 mm
Hg is considered diagnostic of PACG.
2. Mydriatic provocative test is usually not preferred
now-a-days because this is not physiological. In
this test either a weak mydriatic (e.g., 0.5%
tropicamide) or simultaneously a mydriatic and
miotic (10% phenylephrine and 2% pilocarpine)
are used to produce a mid-dilated pupil. A
pressure rise of more than 8 mm Hg is considered
positive.

Inferences from provocative tests

A positive provocative test indicates that angle is
capable of spontaneous closure.
A negative provocative test in the presence of a
narrow angle of anterior chamber does not rule
out a possibility of spontaneous closure. So,
patient should be warned of possible symptoms
of an attack of PACG.

Treatment Fig. 9.17. Van Herick method of slit-lamp grading of angle
width: A, Grade IV; B, Grade III; C, Grade II; and D, Grade I,
Prophylactic laser iridotomy should be performed and E Grade 0. PACD = Peripheral anterior chamber depth;
in both eyes of all the patients diagnosed as latent
angle-closure glaucoma. If untreated, the risk of acute CT = Corneal Thickeners
pressure rise during the next 5 years is about 50%.

228 Comprehensive OPHTHALMOLOGY

Subacute or intermittent primary angle-closure Clinical course
glaucoma
Eyes with subacute primary angle-closure glaucoma
In subacute primary angle-closure glaucoma without treatment may have variable course :
(Subacute PACG) there occurs an attack of transient
rise of IOP (40-50 mmHg) which may last for few Some eyes may develop an attack of acute primary
minutes to 1-2 hours. Such an attack in a patient with angle-closure glaucoma and
occludable angle is usually precipitated by : Others may develop chronic primary angle-closure
glaucoma without passing through acute stage.
Physiological mydriasis is e.g., while reading in
dim illumination, watching television or cinema in Diagnosis and treatment
a darkened room, or during anxiety (sympathetic
overactivity); or Same as described for latent primary angle-closure
glaucoma (see page 227).
Physiological shallowing of anterior chamber Differential diagnosis of coloured halos in PACG.
after lying in prone position. Coloured halos in PACG occur due to accumulation
of fluid in the corneal epithelium and alteration in the
Clinical features refractive condition of the corneal lamellae. Patient
typically gives history of seeing colours distributed
Symptoms. The episode of subacute PACG is marked as in the spectrum of rainbow (red being outside and
by experience of unilateral transient blurring of vision, violet innermost) while watching on a lighted bulb or
coloured halos around light, headache, browache and the moon.
eyeache on the affected side.
The coloured halos in glaucoma must be
Self-termination of the attack occurs possibly differentiated from those found in acute purulent
due to physiological miosis induced by bright conjunctivitis and early cataractous changes. In
light, sleep or otherwise. conjunctivits, the halos can be eliminated by irrigating
Recurrent attacks of such episodes are not the discharge. The halos of glaucoma and immature
uncommon. Between the recurrent attacks the cataract may be differentiated by Fincham's test in
eyes are free of symptoms. which a stenopaeic slit is passed across the pupil.
Signs. Usually during examination the eye is white During this test glaucomatous halo remains intact,
and not congested. However, all the signs described while a halo due to cataract is broken up into
in latent primary angle-closure glaucoma can be segments (Fig. 9.18).
elicited in this phase also (see page 226).

Fig. 9.18. Emsley-Fincham stenopaeic-slit test demonstrating breaking up of halos due to
immature cataract into different segments.

GLAUCOMA 229

Acute primary angle-closure glaucoma IOP is markedly elevated, usually between 40 and
An attack of acute primary angle closure glaucoma 70 mm of Hg,
occurs due to a sudden total angle closure leading to Optic disc is oedematous and hyperaemic,
severe rise in IOP. It usually does not terminate of its Fellow eye shows shallow anterior chamber and
own and thus if not treated lasts for many days. This a narrow angle (latent angle closure glaucoma).
is sight threatening emergency.
Clinical course of acute primary angle-closure
Clinical features glaucoma.
Symptoms The clinical status of the eye after an attack of acute
PACG with or without treatment is referred to post
Pain. Typically acute attack is characterised by congestive glaucoma (details are given below).
sudden onset of very severe pain in the eye
which radiates along the branches of 5th nerve. Diagnosis
Nausea, vomiting and prostrations are frequently Diagnosis of an attack of primary acute congestive
associated with pain. glaucoma is usually obvious from the clinical features.
Rapidly progressive impairment of vision, However, a differential diagnosis may have to be
redness, photophobia and lacrimation develop in considered :
all cases. 1. From other causes of acute red eye. Acute
Past history. About 5 percent patients give history
of typical previous intermittent attacks of subacute congestive glaucoma sometimes needs
angle-closure glaucoma. differentiation from other causes of inflammed
Signs (Fig. 9.19) red eye like acute conjunctivitis and acute
Lids may be oedematous, iridocyclitis (see page 146-147).
Conjunctiva is chemosed, and congested, (both 2. From secondary acute congestive glaucomas
conjunctival and ciliary vessels are congested), such as phacomorphic glaucoma, acute
Cornea becomes oedematous and insensitive, neovascular glaucoma and glaucomatocyclitic
Anterior chamber is very shallow. Aqueous flare crisis.
or cells may be seen in anterior chamber ,
Angle of anterior chamber is completely closed Management
as seen on gonioscopy (shaffer grade 0),
Iris may be discoloured, It is essentially surgical. However, medical therapy is
Pupil is semidilated, vertically oval and fixed. It instituted as an emergency and temporary measure
is non-reactive to both light and accommodation, before the eye is ready for operation.

Fig. 9.19. Clinical photograph of a patient with acute con- (A) Medical therapy
gestive glaucoma. Note ciliary congestion, corneal oede-
1. Systemic hyperosmotic agent intravenous
ma and middilated pupil. mannitol (1 gm/kg body weight) should be given
initially to lower IOP.

2. Acetazolamide (a carbonic anhydrase inhibitor)
500 mg intravenous injection followed by 250 mg
tablet should be given 3 times a day.

3. Analgesics and anti-emetics as required.

4. Pilocarpine eyedrops should be started after the
IOP is bit lowered by hyperosomtic agents. At
higher pressureiris sphincter is ischaemic and
unresponsive to pilocarpine. Initially 2 percent
pilocarpine should be administered every 30
minutes for 1-2 hours and then 6 hourly.

5. Beta blocker eyedrops like 0.5 percent timolol
maleate or 0.5 percent betaxolol should also be
administered twice a day to reduce the IOP.

230 Comprehensive OPHTHALMOLOGY

6. Corticosteroid eyedrops like dexamethasone or 2. Spontaneous angle opening may very rarely occur
betamethasone should be administered 3-4 times in some cases and the attack of acute PACG may
a day to reduce the inflammation. subside itself without treatment.
Treatment of such cases is similar to that of subacute
(B) Surgical treatment angle-closure glaucoma.

1. Peripheral iridotomy. It is indicated when 3. Chronic congestive angle-closure glaucoma is
peripheral anterior synechiae are formed in less continuation of acute congestive angle-closure
than 50 percent of the angle of anterior chamber glaucoma when not treated or when laser P.I. is
and as prophylaxis in the other eye. Peripheral unsuccessful.
iridotomy re-establishes communication between Clinical features are:
posterior and anterior chamber, so it bypasses
the pupillary block and thus helps in control of The IOP remains constantly raised,
PACG. Its surgical technique is described on The eye remains permanently congested and
page 237. irritable, but pain is reduced due to acclamatization.
Laser iridotomy, a non-invasive procedure, is a Lids and conjuctival oedema is reduced,
good alternative to surgical iridectomy. Optic disc may show glaucomatous cupping.
Other features are similar to acute congestive
2. Filtration surgery. It should be performed in angle-closure glaucoma.
cases where IOP is not controlled with the best Treatment is always trabeculectomy operation after
medical therapy following an attack of acute medical control of IOP with guarded visual prognosis.
congestive glaucoma and also when peripheral
anterior synechiae are formed in more than 50 4. Ciliary body shut down. It refers to temporary
percent of the angle of the anterior chamber. cessation of aqueous humour secretion due to
Mechanism: Filtration surgery provides an ischaemic damage to the ciliary epithelium after an
alternative to the angle for drainage of aqueous attack of acute PACG.
from anterior chamber into subconjunctival Clinical features in this stage are similar to acute
space.For surgical technique, see page 238. congestive glaucoma except that the IOP is low and
pain is markedly reduced. Subsequent recovery of
3. Clear lens extraction by phacoemulsification with ciliary function may lead to chronic elevation of IOP
intraocular lens implantation by has recent been with cupping and visual field defects.
recommended by some workers.
Treatment includes:
(C) Prophylactic treatment in the normal fellow eye Topical steroid drops to reduce inflammation.
Laser iridotomy should be performed when the
Prophylactic laser iridotomy (preferably) or surgical cornea becomes clear and IOP should be
peripheral iridectomy should be performed on the monitored.
fellow asymptomatic eye. Trabeculectomy is required when IOP rises
constantly.
Postcongestive angle-closure glaucoma
Vogt’s triad may be seen in patients with any type of
As mentioned above, postcongestive angle-closure postcongesive glaucoma and in treated cases of acute
glaucoma refers to the clinical status of the eye after congestive glaucoma. It is characterized by:
an attack of acute PACG with or without treatment. It
may be seen in following four clinical settings : Glaucomflecken (anterior subcapsular lenticular
opacity),
1. Postsurgical postcongestive PACG. This refers to Patches of iris atrophy, and
the clinical status of the eye after laser peripheral Slightly dilated non-reacting pupil (due to
iridotomy (PI) treatment for an attack of acute PACG. sphincter atrophy).
It may occur in two clinical settings :
i. With normalized IOP after successful laser PI, Chronic primary angle-closure glaucoma

the eye usually quitens after some time with or Pathogenesis
without marks of an acute attack (i.e., Vogt’s Chronic primary angle-closure glaucoma (chronic
triad, see below). PACG) results from gradual synechial closure of the
ii. With raised IOP after unsuccessful laser PI, there angle of anterior chamber in following circumstances:
occurs a state of chronic congestive glaucoma. It
needs to be treated by trabeculectomy operation.

GLAUCOMA 231

1. Creeping synechial angle-closure. It always Anterior chamber is very shallow.
starts superiorly and gradually progresses Iris becomes atrophic.
circumferentially to involve the 360° angle over Pupil becomes fixed and dilated and gives a
the period. greenish hue.
Optic disc shows glaucomatous optic atrophy.
2. Attacks of subacute angle-closure glaucoma may Intraocular pressure is high; eyeball becomes
eventually end up in chronic angle-closure stony hard.
glaucoma.
Management of absolute glaucoma
3. Mixed mechanism, i.e., a combination of POAG
with narrow angles. It presents as chronic angle- 1. Retrobulbar alcohol injection: It may be given
closure glaucoma. to relieve pain. First, 1 ml of 2 percent xylocaine
is injected followed after about 5-10 minutes by
Clinical features 1 ml of 80 percent alcohol. It destroys the ciliary
Clinical features are similar to POAG except that angle ganglion.
is narrow. These include :
2. Destruction of secretory ciliary epithelium to
Intraocular pressure (IOP) remains constantly lower the IOP may be carried out by cyclo-
raised. cryotherapy (see page 240) or cyclodiathermy or
Eyeball remains white (no congestion) and cyclophotocoagulation.
painless,
Optic disc may show glaucomatous cupping, 3. Enucleation of eyeball. It may be considered
Visual field defects similar to POAG may occur when pain is not relieved by conservative
(see page 218). methods. The frequency with which a painful
Gonioscopy reveals a variable degree of angle blind eye with high IOP contains a malignant
closure. Permanent peripheral anterior synechiae growth, justifies its removal. For surgical technique
do not usually develop until late. The gonioscopic of enucleation (see page 284).
findings provide the only differentiating feature
between POAG and chronic PACG. Complications. If not treated, due to prolonged high
IOP following complications may occur:
Treatment
Laser iridotomy alone or along with medical 1. Corneal ulceration. It results from prolonged
therapy should be tried first. epithelial oedema and insensitivity. Sometimes,
Trabeculectomy (filtration surgery) is needed corneal ulcer may even perforate.
when the above treatment fails to control IOP.
Prophylactic laser iridotomy in fellow eye must 2. Staphyloma formation. As a result of continued
also be performed. high IOP, sclera becomes very thin and atrophic
and ultimately bulges out either in the ciliary
Absolute primary angle-closure glaucoma region (ciliary staphyloma) or equatorial region
The chronic phase, if untreated, with or without the (equatorial staphyloma).
occurrence of intermittent subacute attacks, gradually
passes into the final phase of absolute glaucoma. 3. Atrophic bulbi. Ultimately the ciliary body
degenerates, IOP falls and the eyeball shrinks.
Clinical features
Painful blind eye. The eye is painful, irritable and SECONDARY GLAUCOMAS
completely blind (no light perception).
Perilimbal reddish blue zone i.e., a slight ciliary Secondary glaucoma per se is not a disease entity,
flush around the cornea due to dilated anterior but a group of disorders in which rise of intraocular
ciliary veins. pressure is associated with some primary ocular or
Caput medusae i.e., a few prominent and enlarged systemic disease. Therefore, clinical features comprise
vessels are seen in long standing cases. that of primary disease and that due to effects of
Cornea in early cases is clear but insensitive. raised intraocular pressure.
Slowely it becomes hazy and may develop
epithelial bullae (bullous keratopathy) or filaments
(filamentary keratitis).

232 Comprehensive OPHTHALMOLOGY

Classification Clinical presentation. Phacomorphic glaucoma
presents as acute congestive glaucoma with features
(A) Depending upon the mechanism of rise in IOP almost similar to acute primary angle-closure
1. Secondary open angle glaucomas in which glaucoma (see page 229) except that the lens in always
cataractous and swollen (Fig. 9.20).
aqueous outflow may be blocked by a
pretrabecular membrane, trabecular clogging, Treatment should be immediate and consists of :
oedema and scarring or elevated episcleral venous Medical treatment to control IOP by i.v. mannitol,
pressure. systemic acetazolamide and topical betablockers.
2. Secondary angle closure glaucomas which may Cataract extraction with implantation of PCIOL
or may not be associated with pupil block. (which is the main treatment of phacomorphic
glaucoma) should be performed once the eye
(B) Depending upon the causative primary disease, becomes quite,
secondary glaucomas are named as follows:
2. Phacolytic glaucoma (Lens protein glaucoma)
1. Lens-induced (phacogenic) glaucomas.
2. Inflammatory glaucoma (glaucoma due to Pathogensis. It is a type of secondary open angle
glaucoma, in which trabecular meshwork is clogged
intraocular inflammation). by the lens proteins and macrophages which have
3. Pigmentary glaucoma. phagocytosed the lens proteins. Leakage of the lens
4. Neovascular glaucoma. proteins occurs through an intact capsule in the
5. Glaucomas associated with irido-corneal hypermature (Morgagnian) cataractous lens.

endothelial syndromes. Clinical features. The condition is characterised by:
6. Pseudoexfoliative glaucoma. Features of congestive glaucoma due to an acute
7. Glaucomas associated with intraocular rise of IOP in an eye having hypermature cataract.
Anterior chamber may become deep and aqueous
haemorrhage. may contain fine white protein particles.
8. Steroid-induced glaucoma.
9. Traumatic glaucoma. Management. It consists of medical therapy to lower
10. Glaucoma-in-aphakia. the IOP followed by extraction of the hypermature
11. Glaucoma associated with intraocular tumours. cataractous lens with PCIOL implantation.

LENS-INDUCED (PHACOGENIC) GLAUCOMAS

In this group IOP is raised secondary to some disorder
of the crystalline lens. It includes following subtypes:

1. Phacomorphic glaucoma Fig. 9.20. Phacomorphic glaucoma. Note ciliary congesti-
on, dilated pupil and intumescent senile cataractous lens.
Causes. Phacomorphric glaucoma is an acute
secondary angle-closure glaucoma caused by :

Intumescent lens i.e., swollen cataractous lens
due to rapid maturation of cataract or sometimes
following traumatic rupture of capsule is the main
cause of phacomorphic glaucoma.
Anterior subluxation or dislocation of the lens
and spherophakia (congenital small spherical
lens) are other causes of phacomorphic glaucoma.

Pathogenesis. The swollen lens pushes the iris
forward and oblitrates the angle resulting in
secondary acute angle closure-glaucoma. Further,
the increased iridocorneal contact also causes
potential pupillary block and iris bombe formation.

GLAUCOMA 233

3. Lens particle glaucoma It includes:
i. Non-specific hypertensive uveitis, and
Pathogenesis. It is a type of secondary open angle ii. Specific hypertensive uveitis syndromes
glaucoma, in which trabecular meshwork is blocked i. Non-specific hypertensive uveitis. It includes all
by the lens particles floating in the aqueous humour. cases of acute inflammation of the anterior uveal tract
It may occur due to lens particles left after accidental associated with raised IOP, other than the specific
or planned extracapsular cataract extraction or hypertensive uveitis syndromes, but inclusive of
following traumatic rupture of the lens. postoperative inflammation.
Clinical features. Raised IOP associated with lens Mechanisms of rise in IOP. A secondary open-angle
particles in the anterior chamber. glaucoma occurs due to trabecular clogging (by
inflammatory cells, exudates and turbid aqueous
Management includes medical therapy to lower IOP humour), trabecular oedema (due to associated
and irrigation-aspiration of the lens particles from the trabeculitis), and prostaglandin–induced rise in IOP.
anterior chamber. Management. It includes treatment of iridocyclitis and
medical therapy to lower IOP by use of hyperosmotic
4. Glaucoma associated with phacogenic uveitis agents, acetazolamide and beta- blocker eyedrops
(timolol or betaxolol).
Pathogenesis. In this condition IOP is raised due to ii. Specific hypertensive uveitis syndromes. These
inflammatory reaction of the uveal tissue excited by include:
the lens matter. Basically, it is also a type of secondary
open angle glaucoma where trabecular meshwork is Fuchs’ uveitis syndrome (see page 160) and
clogged by both inflammatory cells and the lens Glaucomatocyclitic crisis (see page 160).
particles.
2. Post-inflammatory glaucoma
Management consists of medical therapy to lower
IOP, treatment of iridocyclitis with steroids and In it IOP is raised due to after-effects of the
cycloplegics. Irrigation-aspiration of the lens matter iridocyclitis.
from anterior chamber (if required) should always be
done after proper control of inflammation. Mechanisms of rise in IOP. include :
Pupillary block due to annular synechiae or
5. Glaucoma associated with phacoanaphylaxis occlusio pupillae,
In this condition, there occurs fulminating acute Secondary angle-closure with pupil block
inflammatory reaction due to antigen (lens protein) – following iris bombe formation,
antibody reaction. The mechanism of rise in IOP and Secondary angle-closure without pupil block
its management is similar to that of phacogenic due to organisation of the inflammatory debris in
uveitis. the angle.
Secondary open-angle glaucoma due to
GLAUCOMAS DUE TO UVEITIS trabecular scarring and obstruction of the
meshwork.
The IOP can be raised by varied mechanisms in
inflammations of the uveal tissue (iridocyclitis). Even Management. It includes prophylaxis and curative
in other ocular inflammations such as keratitis and treatment.
scleritis, the rise in IOP is usually due to secondary 1. Prophylaxis. Acute iridocylitis should be treated
involvement of the anterior uveal tract.
energetically with local steroids and atropine to
Types. Glaucomas associated with uveitis can be prevent formation of synechiae.
divided into two main groups: 2. Curative treatment. It consists of medical therapy
1. Hypertensive uveitis. to lower IOP (miotics are contraindicated). Surgical
2. Post-inflammatory glaucoma. or laser iridotomy may be useful in pupil block
without angle closure. Filtration surgery may be
1. Hypertensive uveitis performed (with guarded results) in the presence
Hypertensive uveitis refers to acute inflammation of of angle closure.
the anterior uvea associated with raised IOP.

234 Comprehensive OPHTHALMOLOGY

PIGMENTARY GLAUCOMA 3. Secondary angle closure glaucoma— due to
goniosynechiae resulting from contracture of the
It is a type of secondary open-angle glaucoma neovascular membrane (zipper-angle closure).
wherein clogging up of the trabecular meshwork
occurs by the pigment particles. About 50% of Treatment of NVG is usually frustrating.
patients with the pigment dispersion syndrome Panretinal photocoagulation may be carried out
develop glaucoma . to prevent further neovascularization.
Medical therapy and conventional filtration
Pathogenesis. Exact mechanism of pigment shedding surgery are usually not effective in controlling
is not known. It is believed that, perhaps, pigment the IOP.
release is caused by mechanical rubbing of the Artificial filtration shunt (Seton operation) may
posterior pigment layer of iris with the zonular fibrils. control the IOP.

Clinical features. The condition typically occurs in GLAUCOMA ASSOCIATED WITH
young myopic males. Characteristic glaucomatous INTRAOCULAR TUMOURS
features are similar to primary open angle glaucoma
(POAG), associated with deposition of pigment Secondary glaucoma due to intraocular tumours such
granules in the anterior segment structures such as as malignant melanoma (of iris, choroid, ciliary body)
iris, posterior surface of the cornea (Krukenberg’s and retinoblastoma may occur by one or more of the
spindle), trabecular meshwork, ciliary zonules and following mechanisms:
the crystalline lens. Gonioscopy shows pigment
accumulation along the Schwalbe’s line especially Trabecular block due to clogging by tumour
inferiorly (Sampaolesi’s line). Iris transillumination cells or direct invasion by tumour seedlings.
shows radial slit-like transillumination defects in the Neovascularization of the angle.
mid periphery (pathognomonic feature). Venous stasis following obstruction of the vortex
veins.
Treatment. It is exactly on the lines of primary open Angle closure due to forward displacement of
angle glaucoma. iris-lens diaphragm by increasing tumour mass.

NEOVASCULAR GLAUCOMA (NVG) Treatment. Enucleation of the eyeball should be
carried out as early as possible.
It is an intractable glaucoma which results due to
formation of neovascular membrane involving the PSEUDOEXFOLIATIVE GLAUCOMA
angle of anterior chamber. (GLAUCOMA CAPSULARE)
Etiology. It is usually associated with neovas-
cularization of iris (rubeosis iridis). Neovascularization Pseudoexfoliation syndrome (PES) is characterised
develops following retinal ischaemia, which is a by deposition of an amorphous grey dandruff-like
common feature of : material on the pupillary border, anterior lens surface,
posterior surface of iris, zonules and ciliary processes.
Diabetic retinopathy, The exact source of the exfoliative material is still not
Central retinal vein occlusion, known. The condition is associated with secondary
Sickle-cell retinopathy and open-angle glaucoma in about 50 per cent of the
Eales’ disease. cases. Exact mechanism of rise of IOP is also not
Other rare causes are chronic intraocular clear. Trabecular blockage by the exfoliative material
inflammations, intraocular tumours, long-standing is considered as the probable cause. Clinically the
retinal detachment and central retinal artery glaucoma behaves like POAG and is thus managed
occlusion. on the same lines.

Clinical profile. NVG occurs in three stages : GLAUCOMAS-IN-APHAKIA/PSEUDOPHAKIA
1. Pre-glaucomatous stage (stage of rubeosis iridis);
2. Open-angle glaucoma stage— due to formation It is the term used to replace the old term ‘aphakic
glaucoma’. It implies association of glaucoma with
of a pretrabecular neovascular membrane; and aphakia or pseudophakia. It includes following
conditions:

GLAUCOMA 235

1. Raised IOP with deep anterior chamber in early phagocytose the debris from the aqueous humour.
postoperative period: It may be due to hyphaema, Corticosteroids are known to suppress the
inflammation, retained cortical matter or vitreous phagocytic activity of endothelial cells leading to
filling the anterior chamber. collection of debris in the trabecular meshwork
and decreasing the aqueous outflow.
2. Secondary angle-closure glaucoma due to flat Prostaglandin theory. Prostaglandin E and F
anterior chamber. It may occur following long- (PGE and PGF) are known to increase the aqueous
standing wound leak. outflow facility. Corticosteroids can inhibit the
synthesis of PGE and PGF leading to decrease in
3. Secondary angle-closure glaucoma due to pupil aqueous outflow facility and increase in IOP.
block. It may occur following formation of annular
synechiae or vitreous herniation. Note: May be all the above mechanisms and/or some
other mechanism may be responsible for steroid
4. Undiagnosed pre-existing primary open-angle induced glaucoma.
glaucoma may be associated with aphakia/
pseudophakia. Clinical features. Steroid-induced glaucoma typically
resembles POAG (page 215). It usually develops
5. Steroid-induced glaucoma. It may develop in following weeks of topical therapy with strong
patients operated for cataract due to postoperative steroids and months of therapy with weak steroids.
treatment with steroids.
Management. It can be prevented by a judicious
6. Epithelial ingrowth may cause an intractable use of steroids and a regular monitoring of IOP when
glaucoma in late postoperative period by invading steroid therapy is a must. Its treatment consists of:
the trabeculum and the anterior segment
structures. Discontinuation of steroids. IOP may normalise
within 10 days to 4 weeks in 98 percent of cases.
7. Aphakic/pseudophakic malignant glaucoma (see Medical therapy with 0.5% timolol maleate is
page 236). effective during the normalisation period.
Filtration surgery is required occasionally in
STEROID-INDUCED GLAUCOMA intractable cases.

It is a type of secondary open-angle glaucoma which TRAUMATIC GLAUCOMA
develops following topical, and sometimes systemic
steroid therapy. A secondary glaucoma may complicate perforating
as well as blunt injuries.
Etiopathogenesis. It has been postulated that the
response of IOP to steroids is genetically determined. Mechanisms. Traumatic glaucoma may develop by
Roughly, 5 percent of general population is high one or more of the following mechanisms:
steroid responder (develop marked rise of IOP after
about 6 weeks of steroid therapy), 35 percent are Inflammatory glaucoma due to iridocyclitis,
moderate and 60 percent are non-responders. The Glaucoma due to intraocular haemorrhage,
precise mechanism responsible for the obstruction Lens-induced glaucoma due to ruptured, swollen
to aqueous outflow is unknown. Following theories or dislocated lens,
have been put forward : Angle-closure due to peripheral anterior synechiae
formation following perforating corneal injury
Glycosaminoglycans (GAG) theory. Corticos- producing adherant leucoma.
teroids inhibit the release of hydrolases (by Epithelial or fibrous in growth, may involve
stabilizing lysosomal membrane). Consequently trabeculum.
the GAGs present in the trabecular meshwork Angle recession (cleavage) glaucoma due to
cannot depolymerize and they retain water in the disruption of trabecular meshwork followed by
extracellular space. This leads to narrowing of fibrosis.
trabecular spaces and decrease in aqueous
outflow. Management. It consists of medical therapy with
Endothelial cell theory. Under normal topical 0.5 percent timolol and oral acetazolamide,
circumstances the endothelial cells lining the treatment of associated causative mechanism (e.g.,
trabecular meshwork act as phagocytes and

236 Comprehensive OPHTHALMOLOGY

atropine and steroids for control of inflammation) and closure glaucoma). On examination the main features
surgical intervention according to the situation. of the ciliary block glaucoma noted are

CILIARY BLOCK GLAUCOMA Persistent flat anterior chamber following any
intraocular operation,
Ciliary block glaucoma (originally termed as Markedly raised IOP in early postoperative
malignant glaucoma) is a rare condition which may period,
occur as a complication of any intraocular operation. Negative Seidel’s test and
It classically occurs in patients with primary angle Unresponsiveness or even aggravation by
closure glaucoma operated for peripheral iridectomy miotics.
or filtration (e.g. trabeculectomy) surgery. It is Malignant glaucoma may be phakic, aphakic or
characterised by a markedly raised IOP associated pseudophakic.
with shallow or absent anterior chamber.
Management. Medical therapy consists of 1 percent
Mechanism of rise in IOP. It is believed that, rarely atropine drops or ointment to dilate ciliary ring and
following intraocular operation, the tips of ciliary break the cilio-lenticular or cilio-vitreal contact,
processes rotate forward and press against the acetazolamide 250 mg QID and 0.5 percent timolol
equator of the lens in phakic eyes (cilio-lenticular maleate eyedrops to decrease aqueous production,
block) or against the intraocular lens (cilio-IOL and intravenous mannitol to cause deturgesence of
block) or against the anterior hyaloid phase of the vitreous gel. YAG laser hyaloidotomy can be
vitreous in aphakic eyes (cilio-vitreal block) and thus undertaken in aphakic and pseudophakic patients. If
block the forward flow of aqueous humour, which is the condition does not respond to medical therapy in
diverted posteriorly and collects as aqueous pockets 4-5 days, surgical therapy in the form of pars plana
in the vitreous (Fig. 9.21). As a consequence of this vitrectomy with or without lensectomy (as the case
the iris lens diaphragm is pushed forward, IOP is may be) is required when the above measures fail. It
raised and anterior chamber becomes flat. is usually effective, but sometimes the condition
tends to recur.
Clinical features. Patient develops severe pain and
blurring of vision following any intraocular operation Note : It is important to note that the fellow eye is
(usually after peripheral iridectomy, filtering surgery also prone to meet the same fate.
or trabeculectomy in patients with primary angle-

Fig. 9.21. Pockets of aqueous humour in the vitreous GLAUCOMAS ASSOCIATED WITH INTRAOCULAR
in patients with ciliary-block glaucoma. HAEMORRHAGES

Intraocular haemorrhages include hyphaema and/or
vitreous haemorrhage due to multiple causes. These
may be associated with following types of glaucomas:
1. Red cell glaucoma. It is associated with fresh
traumatic hyphaema. It is caused by blockage of
trabeculae by RBCs in patients with massive
hyphaema (anterior chamber full of blood). It may be
associated with pupil block due to blood clot. Blood
staining of the cornea may develop, if the IOP is not
lowered within a few days.
2. Haemolytic glaucoma. It is an acute secondary
open angle glaucoma due to the obstruction
(clogging) of the trabecular meshwork caused by
macrophages laden with lysed RBC debris.
3. Ghost cell glaucoma. It is a type of secondary
open angle glaucoma which occurs in aphakic or

GLAUCOMA 237

pseudophakic eyes with vitreous haemorrhage. After SURGICAL PROCEDURES FOR
about 2 weeks of haemorrhage the RBCs degenerate, GLAUCOMA
lose their pliability and become khaki-coloured cells
(ghost cells) which pass from the vitreous into the PERIPHERAL IRIDECTOMY
anterior chamber, and block the pores of trabeculae Indications
leading to rise in IOP. 1. Treatment of all stages of primary angle-closure

4. Hemosiderotic glaucoma. It is a rare variety of glaucoma.
secondary glaucoma occurring due to sclerotic 2. Prophylaxis in the fellow eye.
changes in trabecular meshwork caused by the iron Note. Laser iridotomy should always be perferred over
from the phagocytosed haemoglobin by the surgical iridectomy.
endothelial cells of trabeculum.

GLAUCOMAS ASSOCIATED WITH Surgical technique (Fig. 9.22)
IRIDOCORNEAL ENDOTHELIAL SYNDROMES 1. Incision. A 4 mm limbal or preferably corneal

Iridocorneal endothelial (ICE) syndromes include three incision is made with the help of razor blade
clinical entities: fragment.
2. Iris prolapsed. The posterior lip of the wound is
Progressive iris atrophy, depressed so that the iris prolapses. If the iris
does not prolapse, it is grasped at the periphery
Chandler’s syndrome, and with iris forceps.
3. Iridectomy. A small full thickness piece of iris is
Cogan-Reese syndrome. excised by de Wecker's scissors.
4. Reposition of iris. Iris is reposited back into the
Pathogenesis. The common feature of the ICE anterior chamber by stroking the lips of the
syndromes is the presence of abnormal corneal wound or with iris repositors.
endothelial cells which proliferate to form an 5. Wound closure is done with one or two 10-0
endothelial membrane in the angle of anterior nylon sutures with buried knots.
chamber. Glaucoma is caused by secondary synechial 6. Subconjunctival injection of dexamethasone 0.25
angle-closure as a result of contraction of this ml and gentamicin 0.5 ml is given.
endothelial membrane. 7. Patching of eye is done with a sterile eye pad
and sticking plaster.
Clinical features. The ICE syndromes typically affect
middle-aged women. The raised IOP is associated GONIOTOMY AND TRABECULOTOMY
with characteristic features of the causative condition.
These operations are indicated in congenital and
In ‘progressive iris atrophy’, iris features developmental glaucomas. For details, see page
predominate with marked corectopia, atrophy and 213.
hole formation.
FILTERING OPERATIONS
While in Chandler’s syndrome, changes in iris
are mild to absent and the corneal oedema even Filtering operations provide a new channel for
at normal IOP predominates. aqueous outflow and successfully control the IOP
(below 21 mm of Hg). Fistulizing operations can be
Hallmark of Cogan-Reese syndrome is nodular or divided into three groups :
diffuse pigmented lesions of the iris (therefore 1. Free-filtering operations (Full thickness fistula).
also called as iris naevus syndrome) which may
or may not be associated with corneal changes. These are no longer performed now-a-days,
because of high rate of postoperative
Treatment is usually frustating : complications. Their names are mentioned only
for historical interest. These operations included
Medical treatment is often ineffective

Trabeculectomy operation usually fails,
Artificial filteration shunt may control the IOP.

238 Comprehensive OPHTHALMOLOGY

Fig. 9.22. Technique of peripheral iridectomy: A, anterior 2. Primary open-angle glaucoma not controlled with
limbal incision to open the anterior chamber; B, prolapse of medical treatment.
peripheral iris by pressure at the posterior lip of the incision;
C, excision of the prolapsed knuckle of the iris by de Weck- 3. Congenital and developmental glaucomas where
trabeculotomy and goniotomy fail.
er's scissors; D, suturing the wound.
4. Secondary glaucomas where medical therapy is
Elliot's sclero-corneal trephining, punch not effective.
sclerectomy, Scheie's thermosclerostomy and
iridencleisis. Mechnanisms of filtration
2. Guarded filtering surgery (Partial thickness fistula 1. A new channel (fistula) is created around the
e.g., trabeculectomy).
3. Non-penetrating filtration surgery e.g., deep margin of scleral flap, through which aqueous
sclerectomy and viscocanalostomy. flows from anterior chamber into the
subconjunctival space.
Trabeculectomy 2. If the tissue is dissected posterior to the scleral
Trabeculectomy, first described by Carain in 1980 is spur, a cyclodialysis may be produced leading to
the most frequently performed partial thickness increased uveoscleral outflow.
filtering surgery till date. 3. When trabeculectomy was introduced, it was
thought that aqueous flows through the cut ends
Indications of Schlemm’s canal. However, now it is established
1. Primary angle-closure glaucoma with peripheral that this mechanism has a negligible role.

anterior synechial involving more than half of the Sugical technique of trabeculectomy (Fig. 9.23)
angle.
1. Initial steps of anaesthesia, cleansing, draping,
exposure of eyeball and fixation with superior
rectus suture are similar to cataract operation
(see page 187).

2. Conjunctival flap (Fig. 9.23A). A fornix-based or
limbal-based conjunctival flap is fashioned and
the underlying sclera is exposed. The Tenon’s
capsule is cleared away using a Tooke’s knife,
and haemostasis is achieved with cautery.

3. Scleral flap (Fig. 9.23B). A partial thickness
(usually half) limbal-based scleral flap of 5 mm ×
5 mm size is reflected down towards the cornea.

4. Excision of trabecular tissue (Fig. 9.23B): A
narrow strip (4 mm × 2 mm) of the exposed deeper
sclera near the cornea containing the canal of
Schlemm and trabecular meshwork is excised.

5. Peripheral iridectomy (Fig. 9.23C). is performed
at 12 O’clock position with de Wecker’s scissors.

6. Closure. The scleral flap is replaced and 10-0
nylon sutures are applied. Then the conjunctival
flap is reposited and sutured with two interrupted
sutures (in case of fornix-based flap) or
continuous suture (in case of limbal-based flap)
(Fig. 9.23D).

7. Subconjunctival injections of dexamethasone and
gentamicin are given.

8. Patching. Eye is patched with a sterile eye pad
and sticking plaster or a bandage.

GLAUCOMA 239

4. Patients treated with topical antiglaucoma
medications (particularly sympathomimetics) for
over three years.

5. Chronic cicatrizing conjunctival inflammation.
Antimetabolite agents. Either 5-fluorouracil (5-FU)
or mitomycin-C can be used. Mitomycin-C is only
used at the time of surgery. A sponge soaked in 0.02%
(2 mg in 10 ml) solution of mitomycin-C is placed at
the site of filtration between the scleral and Tenon’s
capsule for 2 minutes, followed by a thorough
irrigation with balanced salt solution.

Sutureless trabeculectomy

Sutureless trabeculectomy can be done through a
valvular sclero-corneal tunnel incision ( 4mm × 4 mm
size) using a specially designed Kelly’s punch
(Fig. 9.24). IOP reduction is inferior to that achieved
with conventional trabeculectomy.

Fig. 9.23. Technique of trabeculectomy: A, fornix-based Non-penetrating filteration surgery
conjunctival flap; B & C, partial thickness scleral flap and
excision of trabecular tissue; D, peripheral iridectomy and Recently some techniques of non-penetrating
filteration surgery (in which anterior chamber is not
closure of scleral flap; E, closure of conjunctival flap. entered) have been advocated to reduce the incidence
of post-operative endophthalmitis, overfiltration and
Complications hypotony. Main disadvantage of non-penetrating
A few common complications are postoperative filteration surgery is inferior IOP control as compared
shallow anterior chamber, hyphaema, iritis, cataract to conventional trabeculectomy. The two currently
due to accidental injury to the lens, and used procedures are:
endophthalmitis (not very common). 1. Deep sclerectomy. In this procedure, after making
a partial thickness scleral flap, (as in conventional
Use of antimetabolites with trabeculectomy trabeculectomy, Fig.9.23A), a second deep partial-
It is recommended that antimetabolites should be used thickness scleral flap is fashioned and excised leaving
for wound modulation, when any of the following behind a thin membrane consisting of very thin sclera,
risk factors for the failure of conventional trabeculum and Descemet’s membrane (through
trabeculectomy are present : which aqueous diffuses out). The superficial scleral
1. Previous failed filtration surgery. flap is loosly approximated and conjunctival incision
2. Glaucoma-in-aphakia. is closed.
3. Certain secondary glaucomas e.g. inflammatory 2. Viscocanalostomy. It is similar to deep
sclerectomy, except that after excising the deeper
glaucoma, post-traumatic angle recession scleral flap, high viscosity viscoelastic substance is
glaucoma, neovascular glaucoma and glaucomas injected into the Schlemm's canal with a special
associated with ICE syndrome. cannula.

ARTIFICIAL DRAINAGE SHUNT OPERATIONS

Artificial drainage shunts or the so called glaucoma
valve implants are plastic devices which allow
aqueous outflow by creating a communication
between the anterior chamber and sub-Tenon’s space.