DJO_Oct_Dec_2022

Abstract Case Report Introduction Lid coloboma is a congenital disorder which occurs due to defect in the embryonic fusion of eyelid.1 It occurs in 1 in 10000 births as reported by Pagon et al in 1981.2 Lid coloboma can be unilateral or bilateral, symmetrical or asymmetrical, involve the upper or lower eyelid and may or may not be associated with other ocular or systemic anomalies. The upper eyelid colobomas are clinically more significant and require prompt management compared to lower eyelid colobomas as it may result in exposure keratopathy or conjunctival keratanization leading to visual disturbances.3 Lid abnormalities like conjunctival adhesions, defective tarsal plate, orbicularis muscle or skin and syndromes like Goldenhar syndrome, Treacher Collins syndrome, CHARGE syndrome etc have been described in association to upper lid colobomas in literature.3,4 We describe two cases of upper eyelid coloboma requiring different surgical techniques due to their age of presentation, location and extent. Both cases presented to our hospital almost simultaneously. Case: 1 Case 1: A 15-year-old female with right upper lid congenital coloboma measuring 15 mm horizontally and 7mm vertically involving the middle part of upper eyelid (horizontal extent >50% of eyelid) (Figure 1A). On closing the right eye sclera was visible without corneal exposure suggesting excellent Bell’s phenomenon (Figure 1B). No conjunctival xerosis was seen. Extraocular movements were full and free. No adhesions were seen with the cornea or in the fornices. Routine ocular examination was within normal limits and systemic examination revealed no congenital anomaly. She presented to us for cosmetic correction. In view of the location (central eyelid) along with the extent (horizontal extent >50% of eyelid), a full thickness advancement flap from the lower lid (Cutler beard Surgery) Congenital upper lid colobomas can present as an isolated embryonic defect or as a part of a syndrome. Through a series of two cases this article highlights the importance of different surgical techniques, individualised for congenital upper lid coloboma presenting at different age groups with different location of lid defects. Case 1: Fifteen-year-old female with right upper lid congenital coloboma involving middle one third of the eyelid was planned for transposition of full thickness flap of lower eyelid following the principles of Cutler Beard surgery. Case 2: Oneyear-old female presented with right upper lid eccentric coloboma involving medial aspect of lid, not involving the lacrimal drainage system. A Tenzel Semicircular rotational flap for repair of the defect was planned. This approach was preferred because of the eccentric lid defect and to prevent iatrogenic occlusion amblyopia from any procedures requiring obstruction of visual axis as may occur in Cutler Beard procedure. Keywords : Upper Lid Coloboma; Surgical Management; Cutler Beard Surgery; Tenzel Semicircular Flap; Prevent Iatrogenic Amblyopia; Age At Presentation Address for correspondence: Nitika Beri, MBBS, MS, DNB(Ophthalmology) Department of Ophthalmology, University College of Medical Sciences and GTB Hospital, Dilshad Garden, Delhi, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Beri N, Das GK, Sahu PK, Sharma I, Bhatia R, Kumar N. Customised surgical management of congenital upper lid coloboma. Delhi J Ophthalmol 2022;32:46-9. Customised Surgical Management of Congenital Upper Lid Coloboma Nitika Beri1 , Gopal Krushna Das1 , Pramod Kumar Sahu1 , Isha Sharma1 , Rahul Bhatia2 , Nitish Kumar1 1 Department of Ophthalmology, University College of Medical Sciences and GTB Hospital, Dilshad Garden, Delhi, 2 Department of Ophthalmology, Lady Hardinge Medical College and Associated Hospitals, Delhi, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_78_23 Submitted: 26-Feb-2022 Accepted: 07‑Feb‑2023 Published: 31-May-2023 46 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

was planned. The margins of the coloboma were freshened (Figure 1C). Advancement of full thickness flap from lower lid to upper lid defect, followed by suturing in layers was done (following the principles of Cutler Beard surgery5 )(Figure 1D). The second stage of Cutler Beard surgery was performed after 8 weeks. The defect was fully repaired with good matching of skin texture and colour with acceptable lid margin integrity. The patient was satisfied with the postoperative cosmetic outcome. (Figure 1E). Case: 2 Case 2: A 1 year old female child presented with eccentric right upper lid coloboma measuring 10 mm horizontally and 6 mm vertically, involving the medial aspect of eyelid (Figure 2A). On ocular examination, the medial canthus and the lacrimal drainage system were intact. Normal looking eyelashes extending upto the margins of the lid defect were seen. The child had transparent cornea with excellent Bell’s phenomenon in the affected eye. Local ocular examination revealed dermolipoma having tuft of hair emanating from the ocular surface. It was seen on the temporal side of conjunctiva, not involving the cornea (Figure 2C). Extraocular movements were full and free. No adhesions were seen with cornea or at the fornices. Rest of the ocular examination was within normal limits. On general physical examination, pre-auricular tags were seen on both sides of the face (Figure 2B). After paediatric, orthopaedic and dental consultation no cardiac, renal, skeletal, vertebral or facial anomalies were found. Based on the above classical ocular and ear anomalies, a diagnosis of Goldenhar syndrome was made. On considering the vulnerable age to amblyopia (1 year), no procedure was adopted that would cause occlusion to visual axis. Another important factor considered was the medial location of the defect, hence, a Tenzel semicircular rotational flap for lid reconstruction was planned for the child. Salient points of this technique includes lateral canthotomy and cantholysis after freshening the margins of lid coloboma (Figure 2C). As advocated by Tenzel R(1975)6 an adequate size of Tenzel flap was fashioned and tissues approximated (Figure 2D). Approximation of the eyelashes was excellent without any tissue interposition. The postoperative result was satisfactory both functionally and cosmetically (Figure 2E). Dermolipoma was managed conservatively owing to its small size (not occluding the visual axis). The patient is on regular follow up and may be planned for intervention if needed. Discussion Upper lid coloboma carries an inherent risk of damage to ocular structures if not treated at appropriate time. The chance of corneal involvement is more in cases with deficient or absent Bell’s phenomenon. Even with excellent Bell’s phenomena, xerosis of conjunctiva may still occur. The chances of traumatic injury particularly in paediatric population is high as the eyeball is exposed to external environment. Along with the above, cosmetic correction of lid defect is also a major indication for repair of lid coloboma. Figure 1: (Case 1) with right central upper lid coloboma and its management (1A): Upper lid defect due to the coloboma (1B): Excellent Bell’s phenomenon causing no corneal exposure (1C): Margins of the lid coloboma freshened during surgery (1D): Principles of Cutler Beard surgery followed for surgical management of the lid coloboma (1E): Satisfactory post-operative result A B C D E Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 47

Surgical management options for upper lid colobomas involving <25% of eyelid are direct closure and >25% of eyelid involvement are Cutler Beard surgery (lid sharing surgery), eyelid switch or rotational flap (example Mustarde’s flap) or graft from contralateral normal eye. 5,7,8 In this case series, Case 1 had central lid defect involving >50% of eyelid hence Cutler Beard technique was preferred. Advantages of this technique includes simultaneous repair of anterior and posterior lamellae both acting as a flap (have their own blood supply) hence chance of uptake is excellent. Excellent match of skin colour and texture occurs. However, disadvantage with this procedure is that both the lids remain fused for 6-8 weeks which may cause discomfort to the patient. The patient in case 1 was beyond the amblyopic age (15 years), there is least chance of occlusion amblyopia which may happen in carrying out this procedure in a relatively younger child. Another disadvantage is unable to maintain the continuity of eyelashes with this procedure. In Case 2, due to medial location of the lid defect along with the need to prevent occlusion of the visual axis (amblyopic age 1 year), Tenzel Semicircular rotational flap was performed in this case. This technique being a one stage procedure, avoids the need for multiple general anaesthesia. The eyelashes of the patient are maintained in the reconstructed eyelid. Cutler Beard surgery was not preferred for case 2 because it is not advisable in eccentrically located lid defect, as seen in this patient. It involves eyelid closure for 6-8 weeks which could predispose the patient to occlusion induced amblyopia. Also, this technique requires two stages hence would need a minimum of two general anaesthesia for the child. Lid reconstructive surgery for upper lid coloboma needs meticulous planning and appropriate choice of surgery to achieve excellent cosmetic and functional outcomes. Cutler Beard procedure is ideal in central eyelid defect involving nearly 50% of lid. However, in young child (as in case 2 of this series) may lead to iatrogenic occlusion induced amblyopia and the need for two stage surgery requiring multiple exposure to general anaesthesia makes it a poor choice for such patients. Advantage of Tenzel flap is that it’s ideal for eccentric lid defects and the close approximation of the eyelashes without tissue interposition gives a better cosmetic look. In patients with syndromic association like Goldenhar syndrome, a multidisciplinary approach must be considered for extraocular anomalies. Conclusion Surgical technique for repair of upper lid coloboma has to be decided and carried out based on age of the patient, size of the Figure 2: (Case 2) with right eccentric upper lid coloboma and its management (2A): Medially located upper lid coloboma (2B):Preauricular tags seen (2C): Dermolipoma on temporal side of the conjunctiva. Principles of Tenzel semicircular rotational flap followed for surgical management of the lid coloboma (2D): Immediate post-operative picture depicting good approximation of eyelashes (2E): Satisfactory post-operative result A B C D E 48 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

defect, location of the lid defect, Bell’s phenomenon along with associated ocular and systemic associations for best functional and cosmetic outcome. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Pearson AA. The development of the eyelids. Part I. External features. Journal of anatomy. 1980 Jan;130(Pt 1):33. 2. Pagon RA. Ocular coloboma. Surv Ophthalmol. 1981 JanFeb;25(4):223-36. 3. Collin JR. Congenital upper lid coloboma. Australian and New Zealand Journal of Ophthalmology. 1986 Nov;14(4):313-7. 4. Tawfik HA, Abdulhafez MH, Fouad YA. Congenital upper eyelid coloboma: embryologic, nomenclatorial, nosologic, etiologic, pathogenetic, epidemiologic, clinical, and management perspectives. Ophthalmic Plastic and Reconstructive Surgery. 2015 Jan;31(1):1. 5. Cutler NL, Beard C. A method for partial and total upper lid reconstruction. American journal of ophthalmology. 1955 Jan 1;39(1):1-7. 6. Tenzel RR. Reconstruction of the central one half of an eyelid. Archives of Ophthalmology. 1975 Feb 1;93(2):125-6. 7. Mustards JC. The use of flaps in the orbital region. Plastic and Reconstructive Surgery. 1970 Feb 1;45(2):146-50. 8. Alghoul M, Pacella SJ, McClellan WT, Codner MA. Eyelid reconstruction. Plastic and reconstructive surgery. 2013 Aug 1;132(2):288e-302e. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 49

Abstract Photo Essay Full Text This is a case of a 25-year-old male, who noticed diminution of vision in both his eyes for the past year. His aided vision was 6/60 in both eyes. Fundus examination showed bilateral hypopigmented flecks in all quadrants and bull’s eye maculopathy (right eye is shown in Figure A), which was accentuated on using green-free filter (B) and autofluorescence (C). OCT macula revealed a blunted contour and foveal thinning, while OCT-Angiography showed an enlarged foveal avascular zone (D). The patient was diagnosed with Stargardt disease and has been kept on follow up. Stargardt disease is the most common macular dystrophy, in which there is bilateral progressive central visual loss and subretinal deposit of substances like lipofuscin.1 It is autosomal recessive and is associated with the gene ABCA4. Symptoms include bilateral central diminution of vision, central scotoma and dyschromatopsia; signs are yellow– white flecks at the posterior pole and a characteristic macular atrophy.2 Multimodal imaging in Stargardt disease is useful in the diagnosis and monitoring it. Fundus fluorescein angiography (FFA) classically shows a ‘dark choroid’ due to the RPE-laden lipofuscin blocking the underlying choroidal fluorescence. Fundus autofluorescence (FAF) works as lipofuscin is autofluorescent and helps in assessing the distribution of RPE lipofuscin non-invasively. OCT may be used to monitor progression by measuring changes in including macular thickness and volume, outer nuclear layer (ONL) thickness, outer retinal thickness, and loss of the inner segment ellipsoid layer.2 OCT Angiography has been shows to demonstrate a reduction the superficial and deep capillary plexus, and the choriocapillaris, along with retinal thinning.3 Stargardt Disease is the most common macular dystrophy, and multimodal image can be used for diagnosis and monitoring of the disease. Keywords: Stargardt Disease; Oct Angiography; Autofluorescence Address for correspondence: Shruti Bhattacharya, MBBS, MS, DNB, MNAMS, FICO Department of Ophthalmology Retina Clinic, Guru Nanak Eye Centre, New Delhi, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Bhattacharya S, Chawla K, Gupta P, Thakar M. Multimodal imaging in a case of stargardt’s disease. Delhi J Ophthalmol 2022;32:50-1. Multimodal Imaging in a Case of Stargardt’s Disease Shruti Bhattacharya, Khushboo Chawla, Priyadarshi Gupta, Meenakshi Thakar Department of Ophthalmology, Guru Nanak Eye Centre, New Delhi, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_79_23 Submitted: 01‑Jan‑2023 Accepted: 24‑Jan‑2023 Published: 31-May-2023 50 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

There are unfortunately no proven treatments, and trails are underway involving gene replacement therapy, stem cell therapy and pharmacological approaches.2 Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Heath Jeffery RC, Chen FK. Stargardt disease: Multimodal imaging: A review. Clin Exp Ophthalmol. 2021;49(5):498-515. 2. Tanna P, Strauss RW, Fujinami K, Michaelides M. Stargardt disease: clinical features, molecular genetics, animal models and therapeutic options. Br J Ophthalmol. 2017;101(1):25-30. 3. Mastropasqua R, Toto L, Borrelli E, et al. Optical Coherence Tomography Angiography Findings in Stargardt Disease. PLoS One. 2017;12(2):e0170343. Figure 1: (A) Colour fundus photograph of the right eye showing characteristic yellow–white retinal flecks distributed throughout the retinal with bullseye macular atrophy. (B) Corresponding green-free image accentuates the subretinal flecks. (C) Fundus autofluorescence image showing flecks of both increased and decreased autofluorescence and reduced central macular autofluorescence surrounded by an increased signal, showing the classical atrophy. (D) SD-OCT macula revealed a blunted contour and foveal thinning, with a central macular thickness of 147 microns, while OCT-Angiography showed an enlarged foveal avascular zone. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 51

Abstract Photo Essay Full Text A 8-year-old female presented to the emergency department with sudden pain and diminution of vision in the right eye (OD). Slit lamp evaluation revealed an anteriorly luxated phakic crystalline lens with 360° visibility of the lens equator OD (Figure 1); the left eye (OS) revealed a small spherical lens with a visible equator on dilatation. Anterior chamber (AC) was shallow with a Van Herick grade 2 in both eyes (OU). Her best corrected visual acuity (BCVA) was counting fingers close to face (CFCF) in OD and 20/50 in OS with a correction of -14.5D, due to lenticular myopia. Intraocular pressures (IOP) were 20 and 14 mm of Hg in OD and OS, respectively. Anterior segment optical coherence tomography (AS-OCT) and Scheimpflug imaging showed a spherical luxated phakic lens in the AC in contact with the corneal endothelium (Figure 2). Angle evaluation with AS-OCT showed narrowing of angle recess with an occludable angle (Figure 3). Fundus evaluation did not show any glaucomatous changes. Lensectomy was done via the limbal route along with surgical peripheral iridectomy in OD. Lens diameter was measured to be 7.5 mm. Patient was left aphakic primarily, in view of no capsular bag support and was planned contact lens fitting to counteract anisometropia until secondary IOL surgery. One month following secondary IOL surgery, BCVA improved to 20/50, and IOP dropped to 16 mm Hg, with deepening of the anterior chamber. Prophylactic laser peripheral iridotomy was performed for OS. Rarely, microspherophakia presents as isolated finding.1,2 Microspherophakia can be inherited as both autosomal dominant (AD) or autosomal recessive (AR) variant depending on the gene involved. Mutation of FBN1 gene has been reported in AD variants, whereas mutations of ADAMTS10, ADAMTS17 and LTBP2 have been associated with the AR variants.3 Patients with microspherophakia are generally prone to glaucoma due to angle closure as a result of pupillary block or anterior luxation of the lens. It can also be due the agenesis of the angle structures. Hence, vigilant monitoring is required for timely intervention.4-7 Microspherophakia usually presents with various systemic and ocular features, and is rarely as an isolated incident. In this manuscript, we have reported a rare occurrence of bilateral isolated microspherophakia with unilateral total anterior luxation of the phakic crystalline lens into the anterior chamber, in a child with no systemic and other ocular involvement. The crystalline lens was seen touching the corneal endothelium. Anterior segment imaging modalities, timely intervention, genetic studies and glaucoma evaluation have been emphasized in such scenarios. Keywords: Anterior Luxation, Isolated Microspherophakia, Pediatric Address for correspondence: Prasanna Venkatesh Ramesh, MS, DNB, MNAMS, FGSR, FAICO (Glaucoma), FICO (Glaucoma) Department of Glaucoma and Research, Mahathma Eye Hospital Private Limited, No. 6, Seshapuram, Tennur, Trichy, Tamil Nadu, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Ramesh PV, Ramesh SV, Devadas AK, Ray P, Ramesh MK, Rajasekaran R. Unilateral anterior luxation of the crystalline phakic lens in a patient with bilateral isolated microspherophakia. Delhi J Ophthalmol 2022;32:52-3. Unilateral Anterior Luxation of the Crystalline Phakic Lens in a Patient with Bilateral Isolated Microspherophakia Prasanna Venkatesh Ramesh1 , Shruthy Vaishali Ramesh2 , Aji Kunnath Devadas3 , Prajnya Ray3 , Meena Kumari Ramesh2 , Ramesh Rajasekaran4 1 Department of Glaucoma and Research, Mahathma Eye Hospital Private Limited, Trichy, 2 Department of Cataract and Refractive Surgery, Mahathma Eye Hospital Private Limited, Trichy, 3 Department of Optometry and Visual Science, Mahathma Eye Hospital Private Limited, Trichy, 4 Department of Paediatric and Strabismus, Mahathma Eye Hospital Private Limited, Trichy, Tamil Nadu, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_80_23 Submitted: 09‑Dec‑2022 Accepted: 23‑Jan‑2023 Published: 31-May-2023 52 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient’s guardian as given consent for the child’s images and other clinical information to be reported in the journal. The patient’s guardian understands that the child’s name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Microspherophakia: Genetics, Diagnosis, and Management [Internet]. American Academy of Ophthalmology2019 [cited 2022 Jan 21];Available from: https://www.aao.org/eyenet/article/microspherophakia-geneticsdiagnosis-management 2. Chan RT-Y, Collin HB. Microspherophakia. Clin Exp Optom 2002;85(5):294–9. 3. Morales J, Al-Sharif L, Khalil DS, Shinwari JMA, Bavi P, Al-Mahrouqi RA, et al. Homozygous Mutations in ADAMTS10 and ADAMTS17 Cause Lenticular Myopia, Ectopia Lentis, Glaucoma, Spherophakia, and Short Stature. Am J Hum Genet 2009;85(5):558–68. 4. Muralidhar R, Ankush K, Vijayalakshmi P, George VP. Visual outcome and incidence of glaucoma in patients with microspherophakia. Eye (Lond) 2015;29(3):350–5. 5. Senthil S, Rao HL, Babu JG, Mandal AK, Addepalli UK, Garudadri CS. Outcomes of trabeculectomy in microspherophakia. Indian J Ophthalmol 2014;62:601-5. 6. Caglar C, Yasar T. Glaucoma caused by isolated microspherophakia: A long story. Indian Journal of Ophthalmology. 2014;62(11):1106. 7. Senthilkumar VA, Pradhan C, Rajendrababu S, Mishra C, Kannan NB. Management of microspherophakia and angle-closure glaucoma in Goldenhar syndrome. Indian J Ophthalmol Case Rep 2022;2:98-100. Figure 1: Slit lamp photography of right eye (OD) showing an anteriorly luxated spherical shaped crystalline lens in the anterior chamber, with the equator visible all around Figure 2: (a) Anterior segment optical coherence tomography (AS-OCT) and (b and c) Scheimpflug imaging in default and inverse colour showing a spherical luxated phakic lens in the anterior chamber touching the corneal endothelium, respectively Figure 3: AS-OCT of the angle of the anterior chamber in OD showing narrow occludable angle Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 53

Omnibus Humanus (Masters, Change makers, Out of box thoughts) Eye donation has achieved laudable heights over past few decades, thanks to active promotion by National Program of Control of Blindness, hard work by ophthalmologist and laborious activity by eye bank staff. The nobility associated with this donation act is appreciated by family and society. However it comes with a grey tinge when the eye bank team lacks the essential element of compassion and empathy for the grieving family. To illustrate this oft relegated element, let’s take a look at an actual occurrence . Event in 2015: A scene from a home in posh central Delhi. An ambulance has just brought the body of a 86 year old lady to her home. A petite person, her delicate features are serenely still in death. After rituals she is laid out on a sheet in the drawing room, with her grieving family saying adieu to her with tears silently stream down their faces. Some members have pulled themselves together and are issuing instructions for the tasks that need to be done. The deceased lady had led a remarkable life and her warmth and graciousness had endeared her to many people. Her granddaughter, after talking to the family, makes a call to a nearby government hospital for eye donation. Her beloved grandma had wished for that. When the eye donation team of a technician and a young resident arrive, they walk in through the gate and straight into the drawing room. Everyone turns to look at them. The resident has a sullen expression. With no preamble or even a sentence of condolence he lets the family know that they have come to retrieve the eyes from the dead body. Just prior to their arrival, the deceased lady’s daughter had asked everyone to give her a few minutes alone with her mother’s body so that she could say farewell to her mother in her own way. This daughter had tended to her partly -paralyzed mother in a devoted fashion for 12 years prior to this day and there was a deep attachment between them. We all happened to be walking out of the room in response to my mother’s request when the eye retrieval team walked in. I introduced myself as an ophthalmologist, thanked the medical team for coming to retrieve my Nani’s eyes and told them to wait a few minutes as my mother needed to do something. There was no acknowledgement by the resident of my being a senior colleague and no compassion for the loss sustained by the family. He just scowled and said “Kindly hurry up, I don’t have all day!” My mother heard this and became distraught. She looked angrily at me and her gaze seemed to say-“why have you brought these rude outsiders into our home at this poignant moment?” In that instant, I was strongly tempted to ask the resident to leave. What saved the day was the courtesy of the accompanying technician, who murmured warmly ‘‘We understand madam, please take your time”. Event in 2021: A gracious 96 year old, the mother of four doctors had breathed her last. A patient of glaucoma she was on medications for over 2 decades. Her wish to donate her eyes had been reiterated to her daughter (a senior ophthalmologist), 3 days prior to her demise. This wish was honored and a team from a reputed eye hospital was called. Again a similar scene was enacted, in presence of the ophthalmologist daughter. No condolences, no gracious look, only robotic collection of blood sample and eyeball. The sampling was difficult and multiple poking was required. The daughter winced, but the senior resident who had come for collection did not even turn around. It was just a body and the duty to be done was precise surgical removal. Communication, empathy, compassion were terms in dictionary unread by the erudite young ophthalmologist. The team sullenly went around their work, covered the eye sockets and went away. No acknowledgement, no thanks, no gesture. This situation faced by these ophthalmologist stayed with them for a lifetime. The wound remained raw and faith in their profession was shaken. Let’s introspect. This was the behavior of the brash young doctor with the family of reputed ophthalmologists, their seniors’! This is still in the power equation. What would be the behavior to a family with no power equation? While training residents to deal with surgical emergencies with competency, why is there lack of teaching them to behave and communicate with a grieving family? We as clinicians, surgeons are dealing with humans. Compare this with Code Krishna practiced in some states, where the deceased is garlanded, and the team bows their head down in prayer to seek safe passage to afterlife for the soul of the donor and give thanks for this noble gesture. We need to remember that the deceased is a valuable member of someone’s family, not just a dead body. The retrieval team must be taught well to handle both accommodating as well as angry relatives (who liken the team to vultures, swooping in on their moment of grief) with calmness and respect. They have to remember that this is one case where the family’s feelings are more important than meeting their cornea targets. For assessing the mood of the relatives, the team has to be fully engaged and excellent listeners. Humility is desirable too. There is a lot to be said for paying our respects to the deceased as well and not just grabbing tissue, even if it is for a noble purpose. Eye Donation: Crucial Bedside Manners of Eyeball Harvesting Team 54 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

My experiences as a student, doctor and patient have driven home to me the importance of good bedside manners. Ideally, this aspect should be a part of the curriculum. How to gently impart the news of a dreaded disease to someone or the unfortunate death of a patient to their relatives- sometimes described as ‘the longest walk.’ It is often said by grateful patients that ‘half my disease disappeared with the way the doctor spoke to me’. A warm atmosphere of trust does generate a positive frame of mind in the patient and boosts immunity, if not more. Our strength as a doctor derives from the gratitude and blessings we receive from patients who get cured under our watch. They are giving us a very prized possession –their trust. It behooves us to accept it with humility. I feel those doctors that become arrogant after many successful cures and think the medicine they practice is all about their own expertise and greatness rather than engaging with the patient’s concerns have lost their way. The best balance is the pursuit of medical excellence with a truly listening ear and a kind heart to complement that. Financial support and sponsorship Nil. This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. Cite This Article as: Mehta A. Eye donation: Crucial bedside manners of eyeball harvesting team. Delhi J Ophthalmol 2022;32:54-5. Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_81_23 Conflicts of interest There are no conflicts of interest. Dr. Anjali Mehta, MBBS, DO, DNBEx-Army Eye-Surgeon, Director, Vasundhara Eye Centre Founder Trustee, Sagar Trust E-mail: [email protected] Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 55

Abstract Theme Section Introduction Technological advances in the field of orbital surgery have provided the surgeon with vast array of tools optimizing pre-operative planning, intraoperative surgical manipulation and post- operative outcome assessment. The role of image guided surgery has been successfully established in several surgical domains of the head and neck region. It elucidates a system comprising of hardware and software that utilize either infra-red cameras or electromagnetic fields to enable the amalgamation of pre-operative and/or intraoperative subject imaging with three-dimensional real-time localization of the surgical instruments on a computer screen in the operating room.1 Its application in the fields of neuro-surgery, skull base surgery and sinus surgery are well known.2 In the context of oculoplastic orbital surgeries, navigation serves to guide the operating surgeon in identifying bony landmarks, planning complex reconstructions with adequate symmetry, precisely localizing orbital tumors and its bony and soft tissue relations to the surrounding structures. In coherence with the navigation system, computer aided manufacturing (CAM) translates two dimensional (2-D) Digital Imaging and Communications in Medicine (DICOM) files into accurate three dimensional (3D) facsimile of the patient’s skeleton and surrounding soft tissues which can be instrumental in reconstructive orbital surgery and for surgical training and education.3 Free hand contouring of orbital implants to reinstate anatomical normalcy in orbital reconstruction is not only challenging but also inaccurate. Availing the benefit of 3D printing such patient-specific implants(PSI) have revamped the outlook of contemporary orbital reconstruction.3 Another noteworthy addition to an orbital surgeon’s armamentarium is the ultrasonic aspirator which has found its application not only in bony decompression of the orbit but in debulking complex orbital tumors. Purpose: This article comprehensively compiles the latest technological and surgical advances in the realm of orbital surgery and their application in the pre-operative, intraoperative and post-operative periods. Methods: A detailed literature research supplemented by a manual search for the functions of image guidance, three-dimensional printing using computer-assisted manufacturing and ultrasonic surgical aspirator in orbital surgery was conducted and the pearls and pitfalls of the aforementioned tools have been enlisted and elaborated. Results: Navigation guided orbital surgery has grown to play a pivotal role in various orbital surgeries such as orbital decompression for thyroid eye disease, post-traumatic orbital fracture repair, and reconstruction, orbital tumor resection, optic canal decompression for traumatic optic neuropathy, extraction of orbital foreign body and endoscopic and lacrimal procedures, by offering enhanced surgical precision. Three-dimensional printing smoothens the potholed road to structural and functional orbital restoration post trauma or surgery. Ultrasonic aspirator is a handy addition, which sophisticates bone and soft tissue removal during decompression or tumor debulking and minimizes the drawbacks of its predecessor technologies. Conclusion: The role of image guidance, three-dimensional printing and ultrasonic surgical aspirator in orbital surgeries still bears the scope for further investigation and holds the future of digitally advanced surgical operation within the orbit at its helm. Keywords: Navigation guidance, Patient specific implant, Ultrasonic aspirator Address for correspondence: Kasturi Bhattacharjee, Director (Clinics and Academics) and Head of Department Department of Ophthalmic Plastic and Reconstructive Surgery, Sri Sankaradeva Nethralaya, Guwahati, Assam, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Bhattacharjee K, Venkatraman V. Newer nuances in orbital surgery. Delhi J Ophthalmol 2022;32:56-60. Newer Nuances in Orbital Surgery Kasturi Bhattacharjee, Vatsalya Venkatraman Department of Ophthalmic Plastic and Reconstructive Surgery, Sri Sankaradeva Nethralaya, Guwahati, Assam, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_82_23 Submitted: 24‑Nov‑2022 Accepted: 16‑Jan‑2023 Published: 31-May-2023 56 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

Principle of image guided navigation system In literature the working of this image guided navigation has been compared to the Global Positioning System (GPS) in order to simplify its understanding. The radiological scans of either Computed Tomography(CT) or Magnetic Resonance Imaging (MRI) performed under the navigation protocol are loaded onto the console for isolation of the target area. The signal emitted from the hand-held pointer shows the surgeon’s intra-operative position with respect to the fixed patient tracker. This aids the surgeon in easy maneuvering without any inadvertent injury to the surrounding tissues. The end point of the surgery is said to have reached when prefixed target and the mobile stylet placed at the tissue level overlap. Intra-operative navigation functions on the basic concept of stereotaxy which involves the use of external reference markers for location of internal surgical landmarks [Figure 1].4 There are two such tracking modalities available. Electromagnetic navigation(Fusion, Medtronic Stealth, Brainlab): The dynamic reference frame(DRF) is mounted onto the head of the patient, an electromagnetic field is created by the same around the surgical site and the movement of the navigation probe in relation to it provides the accurate location. While it is easy to set up, less expensive and provides adequate surface registration, it is less accurate, has a narrower field and it associated with ferromagnetic interference of surgical instruments.4 Optical navigation(Brainlab, Stryker, Medtronic Stealth System): Light sources such as infrared cameras emit beams which reflect the location of the probe using optical sensor thus making it more accurate. It has a larger field and offers both bony and soft tissue registration, but is more expensive, line of sight interference occurs and pinning of the DRF to the skull post is necessary.4 Principle of customized orbital reconstruction using CAM and 3D printing Radiological imaging in 2D after subjecting to mirroring, manual or auto-segmentation and repositioning, is converted into stereolithographic reproductions. These can be used for pre-surgical preparation or to use as a mold and create PSIs’ [Figure 2]. Mirroring technology transposes the orbital wall of the unaffected normal side onto the affected orbit. Evolution Figure 1: The image shows a real time intra-operative position of the navigation stylet in the coronal, axial, sagittal and 3D reconstruction CT view of a patient with optic canal fracture undergoing optic canal decompression. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 57

of CAM led to PSI manufacturing using 3D printing. This bioprinting generates human tissue-like structures in a layer by layer fashion which can be sterilized and used as medical equipment.3 Designer orbital implants have paved the way for reshaping the future of facial reconstruction. Principle of Ultrasonic Aspirator This surgical tool engages low frequency ultrasonic energy to fragment the targeted tissue while concurrently irrigating as well as aspirating the broken down contents from the surgical field.5 The available ultrasonic surgical aspirators in the market are, the CUSA Excel/Clarity (Integra, Plainsboro, NJ (USA)), Sonopet (Stryker, Kalamazoo, MI (USA)), and Söring (Söring GmbH, Quickborn, Germany).6 The entire apparatus contains an ultrasonic handpiece attached to a base control unit which is foot-pedal driven. This base control module regulates the irrigation, aspiration and ultrasound power parameters. It runs on the principle of emulsification by torsional oscillation.7 When compared to a conventional high-speed bone drill, its causes significantly less collateral trauma to adjacent tissues. Orbital Bony Decompression In Thyroid Eye Disease (TED) Orbital decompression in TED is targeted at proptosis reduction or alleviating dysthyroid optic neuropathy. This can be attained by either thinning or removing the lateral wall, medial wall, orbital floor and/or orbital fat. Navigation is useful in identifying bony landmarks for anatomical identification and channelized decompression. The infero-medial strut forms the lower boundary of the medial wall which is usually retained in order to sustain the integrity of the craniofacial skeleton while anterior and posterior ethmoidal arteries demarcate the upper border of the medial wall to avoid encroachment on the cribriform plate.2 The thickness of the greater wing of sphenoid can be quantified in order to estimate the extent of lateral wall decompression required. Orbital apex shows crowding in cases of compressive optic neuropathy in TED. This is an area having vital structures and navigation aids in safe steering through the apex. Pre-operative marking and intraoperative correlation of the target areas aid to determine the end point of decompression.4 Post-operative and preoperative CT scans of the orbits can be compared to assess change in volume and globe position which measures the adequacy of decompression.2 The ultrasonic surgical aspirator when used for bone decompression of the lateral orbital wall in TED, offers the advantage of minimum manual pressure and stability to the surgeon’s hand when compared to a bone drill or saw, which can cause haphazard movements obliterating the surgeon’s field of vision due to scattered bone dust [Figure 3]. Due to its non-rotating nature, the tool works only on the structure in contact with its tip thereby sparing soft tissue damage such as adjoining dura mater which if tampered with can cause cerebrospinal fluid (CSF) leakage. It has been credited with the ability to sculpt bone with ease and minimize bleeding and post-surgical inflammation.5 Facial Trauma Internal Orbital Fracture Challenging orbital fractures include large orbital floor fractures with loss of posterior ledge and combined orbital floor and medial wall fractures.4 The goal of orbital wall fracture repair is to reinstate the normalcy of orbital structure and volume after meticulous repositioning of herniated contents back into the orbit and introducing an auto or allogenic barrier such as a plate to recreate the pre-existing wall. Image guidance in the pre-operative period can be utilized for virtual plate sizing and fitting or for designing PSI. In case of unilateral fractures, the contralateral unaffected orbit is either manually or automatically segmented and mirrored onto the fractured orbit to yield a theoretical shape forming Figure 2: The image shows the 3D reconstruction of the skull of a patient with lateral orbital wall fracture with the prospective location of a patient specific implant (highlighted in pink) Figure 3: The image shows an intraoperative capture of Ultrasonic surgical aspirator being utilized in a case of orbital decompression for Thyroid Eye Disease. The black star is the handpiece of the machine and the black dot marks the aspiration tubing with the emulsified contents 58 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

the necessary skeleton for a PSI.2 This customization provides a close to ideal volumetric correction to compensate for orbital expansion due to fracture (in primary repair) and fat atrophy (delayed repairs).8 Intraoperatively, navigation aids the surgeon to delineate displaced orbital contents, adjacent important neuro-vascular bundles and the location of optic nerve to curtail unwarranted surgical manipulation, ensure appropriate enophthalmos correction and relieve pre-operative motility restriction.4 Mid-facial fracture Complex orbito-facial fractures include zygomatico-maxillary complex, naso-orbito-ethmoid complex, Lefort type fractures and pan facial fractures.4 These fractures result in flattening or displacement of anterior malar prominence and there is incomplete visualization of the entire zygoma through trans-orbital approach which renders the challenge of precise reconstruction. Image guidance allows for pre-operative three-dimensional CT based reconstruction of the skull which helps plan for a functional and aesthetic midface restoration post trauma.2 Inadequate primary repair can increase the facial width from outward bending of the zygomatic arch and appearance of persistent enophthalmos due to inferiorly shifted malar eminence. Computer assisted surgery also helps circumvent hurdles of delayed fracture repair such as malunion, non-union, loss of surrounding soft tissue, callous formation, bony resorption and fibrosis by accurately recognizing osteotomy sites and ensuring proper reduction despite the remodeling ensued.4 Orbital Tumor Resection Navigation system can be used to fashion orbital bone flaps which are essential when large orbital tumors have to be excised. The margins of the tumor are defined using the feature of auto-segmentation pre-operatively. Tumor dimensions are noted both in the x and y axes. Based on this, we can determine the size of the bone flap that needs to be raised. Intraoperatively, the site and size of the lesion can be seen on the console which guides the surgeon to the placement of the horizontal osteotomies. Postoperatively the appropriate repositioning of the flap can be gauged and any residual enophthalmos due to large bony defects left after tumor excision can be assessed for possible symmetrical secondary reconstruction. Dangerous zones can be identified pre-operatively using the angiographic radiological scans and helps circumvent accidental trauma to the adjacent neurovascular bundles.2 When compared to soft tissue lesions, the spatial location of bony lesions is better with the navigation system whereby sites of thinning or secondary hyperostosis such as in the case of meningiomas can be accurately marked to avoid CSF leakage or intracranial injury.4 To improve the visualization of soft tissue lesions, a CT and MRI fusion can be done on the console which is particularly useful in apical lesions to preserve visual function.2 Tumor resection from the orbit can leave behind gaping irregular bony defects which is another indication for PSI as off-the-shelf implants will not give the desired reconstruction.8 Ultrasonic aspirator has been utilized for orbital tumor resections based on consistency, localized adhesions and presence of crucial neurovascular bundles proximal to the lesion. In view of its precise emulsification and sparing of adjoining soft tissues that tends to scatter away from the vibrating tip creating a plane of dissection, this surgical aid is a secure alternative for extraction of infiltrative orbital masses, ones with challenging anatomical access and those with potential of injury to nerves and vessels.7,9 Optic Canal Decompression Stereotactic navigation technology provides enhanced precision and protection by elucidating intra-operative position and orientation of the optic canal anatomy for identification of impinging bone fragments, optic nerve edema or optic nerve sheath hematoma during optic canal decompression for traumatic optic neuropathy. Along with the bony features, the vascular components can be highlighted with differential color coding in the navigation software on the CT angiogram, which acts as a guide intraoperatively to avoid damage to vital structures. A three-dimensional reconstruction can provide information regarding concurrent orbital wall fractures and a single stage surgery involving optic canal decompression and orbital wall reconstruction can be judiciously planned.4 Orbital Foreign Body Extraction Improved image localization of intra-orbital foreign body using the navigation system helps in incision site selection especially in cases of delayed presentation. Using 3D model of the patient, the nearest surface landmark to the foreign body can be measured to optimize the extraction procedure by chalking a surgical path and minimize collateral damage and foreign body displacement. Depth estimation of the foreign body by navigation guidance in case of it being lodged in the orbital apex, aids in safeguarding the optic nerve and apical vessels while removal.10 Endoscopic Orbital And Lacrimal Surgeries Navigation guidance accurately delineates the lacrimal sac and ensures correct resection of the medial wall of the sac avoiding long term failure post endonasal dacryocystorhinostomy.11 Computer assistance intraoperatively tracks the surgeon’s movements enabling him/her with real time visualization of the patient’s anatomy guaranteeing maximal tumor removal.12 Stereotaxis identifies bony anomalies along the lacrimal drainage system present congenitally or secondary to trauma and previous surgery.13 Limitations Navigation console along with its software and other paraphernalia though easy to use, do incur a substantial capital and necessitates an in-depth knowledge of the loading software and associated hardware. Pre-operative planning and intraoperative utilization of the equipment requires time for set up and can therefore possibly prolong the surgeon’s operative duration. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 59

CT and MRI scans compatible with the navigation system are usually of supreme quality and therefore poor-quality scans will be deficient for its evaluation using the software. There is a learning curve on the part of the operating surgeon to become proficient with the technology.2 PSI are designed to fit under the ideal scenario, but the intraoperative realities such as unforeseen fibrosis and scar formation may preclude it from giving the lock and key superimposition and thus necessitate further on table modifications.8 Heat transfer to human soft tissues due to cavitation, inability to tackle extensive bone removals and its cost are the possible limitations of the ultrasonic aspirator.7,9 Conclusion Image guidance, customized orbital reproductions/implants and the ultrasonic surgical aspirator have diverse applications in the field of orbital surgery and further advancements in the same shall continue to improve the operative precision and consequent patient outcomes. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Hussain A, Nijhawan N, DeAngelis D, Oestreicher J. Perceptions and use of computer-assisted surgery (CAS) in the orbit. Orbit. 2019 Jun;38(3):180-183. doi: 10.1080/01676830.2018.1490440. Epub 2018 Jul 11. PMID: 29993308. 2. Campbell AA, Mahoney NR. Use of computer-assisted surgery in the orbit. Orbit. 2022 Apr;41(2):226-234. doi: 10.1080/01676830.2021.1939730. Epub 2021 Jul 13. PMID: 34256667. 3. Grob SR, Yoon MK. Innovations in Orbital Surgical Navigation, Orbital Implants, and Orbital Surgical Training. Int Ophthalmol Clin. 2017 Fall;57(4):105-115. doi: 10.1097/IIO.0000000000000188. PMID: 28885250. 4. Udhay P, Bhattacharjee K, Ananthnarayanan P, Sundar G. Computerassisted navigation in orbitofacial surgery. Indian J Ophthalmol. 2019 Jul;67(7):995-1003. doi: 10.4103/ijo.IJO_807_18. PMID: 31238394; PMCID: PMC6611296. 5. Bengoa-González Á, Galindo-Ferreiro A, Mencía-Gutiérrez E, SánchezTocino H, Martín-Clavijo A, Lago-Llinás MD. Deep Lateral Wall Partial Rim-Sparing Orbital Decompression with Ultrasonic Bone Removal for Treatment of Thyroid-Related Orbitopathy. J Ophthalmol. 2019 Dec 2;2019:9478512. doi: 10.1155/2019/9478512. PMID: 31885895; PMCID: PMC6914951. 6. Henzi S, Krayenbühl N, Bozinov O, Regli L, Stienen MN. Ultrasonic aspiration in neurosurgery: comparative analysis of complications and outcome for three commonly used models. Acta Neurochir (Wien). 2019 Oct;161(10):2073-2082. doi: 10.1007/s00701-019-04021-0. Epub 2019 Aug 3. PMID: 31377957; PMCID: PMC6739453. 7. Ao J, Juniat V, Davis G, Santoreneos S, Abou-Hamden A, Selva D. Outcomes of surgical resection of sphenoid-orbital meningiomas with Sonopet ultrasonic aspirator. Orbit. 2021 Oct;40(5):394-399. doi: 10.1080/01676830.2020.1817099. Epub 2020 Sep 7. PMID: 32894977. 8. Habib LA, Yoon MK. Patient specific implants in orbital reconstruction: A pilot study. Am J Ophthalmol Case Rep. 2021 Oct 19;24:101222. doi: 10.1016/j.ajoc.2021.101222. PMID: 34746511; PMCID: PMC8554165. 9. Bengoa-González Á, Lago-Llinás MD, Mencía-Gutiérrez E, MartínClavijo A, Salvador E, Gimeno-Carrero M. Surgical removal of orbital tumors by orbital approach using ultrasonic surgical system SONOPET®. Orbit. 2022 Apr;41(2):216-225. doi: 10.1080/01676830.2021.1912115. Epub 2021 Apr 16. PMID: 33860737. 10. Zhao Y, Li Y, Li Z, Deng Y. Removal of Orbital Metallic Foreign Bodies with Image-Guided Surgical Navigation. Ophthalmic Plast Reconstr Surg. 2020 May/Jun;36(3):305-310. doi: 10.1097/ IOP.0000000000001580. PMID: 31923090. 11. Reichel O, Taxeidis M. Use of an image-guided navigation system for routine endonasal endoscopic dacryocystorhinostomy. J Laryngol Otol. 2019 Aug;133(8):685-690. doi: 10.1017/S0022215119001567. Epub 2019 Jul 24. PMID: 31337464. 12. Chang CH, Ku WN, Kung WH, Huang Y, Chiang CC, Lin HJ, Tsai YY. Navigation-assisted endoscopic surgery of lacrimal sac tumor. Taiwan J Ophthalmol. 2020 Feb 6;10(2):141-143. doi: 10.4103/tjo.tjo_65_19. PMID: 32874846; PMCID: PMC7442103. 13. Ali MJ, Singh S, Naik MN. Image-guided lacrimal drainage surgery in congenital arrhinia-microphthalmia syndrome. Orbit. 2017 Jun;36(3):137-143. doi: 10.1080/01676830.2017.1280059. Epub 2017 Mar 8. PMID: 28272904. 60 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

Abstract Theme Section Introduction Innovations in Biometry and Iol Power Calculation The precision of IOL power calculation is essentially determined by the accuracy of measurement of axial length (A.L.), keratometry, and anterior chamber depth (ACD) or effective lens position (ELP). Applanation and immersion Ultrasound biometry have now been superseded by Optical biometry using partial coherence interferometry (PCI), optical low coherence reflectometry (OCLR) technology, and swept source-optical coherence tomography (SS-OCT) based technology. Accurate biometry can be performed in pseudophakic and aphakic eyes and eyes with phakic IOLs, myopic eyes with staphyloma, and silicon oil filled eyes.2 Partial coherence interferometry (PCI) The first commercial PCI device was introduced in 2001 (IOL Master, Carl Zeiss Meditec, USA) using a semiconductor diode laser (780 nm). It is a non-contact technique, with no indentation of the cornea, preventing an underestimation of ACD and A.L. It relies on visual fixation to facilitate the measurement along the visual axis, in contrast to acoustical A.L. measured by ultrasonic impulses, which may not correspond exactly to the visual axis. Laser reflection originates from RPE, where the photoreceptors lie, in contrast to the ultrasound method, where the acoustic impulse reflects from ILM. It measures the A.L., ACD, corneal thickness, and IOL power quickly and precisely with high-resolution axial length measurement (about ± 0.02 mm equivalent to 0.05D).3 Optical low coherence reflectometry (OLCR) Like PCI, the laser is replaced by a super luminescent light emitting dioe. The two devices in use are Lenstar LS900 (Haag-Streit, Koeniz, Switzerland) & Allegro Biograph (Wavelight, Erlangen, Germany). Lenstar 900 gives measurements of A.L., ACD, dual-zone WTW, pupillometry, dual-zone keratometry, the magnitude of astigmatism, and an optional T-cone topography.4 Swept Source-OCT Based Technology The first optical biometer to incorporate this technology is IOL MASTER 700, launched in 2014. It provides a full-length OCT image of the eye, provides a fixation check, is more accurate with fewer refractive surprises, and identifies macular pathologies.5 Unique telecentric K and distance independent K and better cataract penetration rates. Cataract surgery is one of the most commonly performed ophthalmic surgeries worldwide and has evolved to improve patient safety and better visual outcomes.1 Several technological innovations include advanced biometry, viscosurgical devices, pupil expansion devices, newer phaco machines, and techniques like Femtosecond laser assistance, intraoperative optical coherence tomography imaging, intraoperative aberrometry, and three-dimensional heads-up visualization paved the way for this new era in cataract surgery. Newer intraocular lenses have emerged to address issues beyond merely refractive status, like accommodation, U.V. protection, and dysphotopsia. This article reviews the emerging innovations in cataract surgery. Keywords: Cataract Surgery, Innovations, Recent Trends Address for correspondence: Arup Chakrabarti, MS, Chakrabarti Eye Care Centre Cataract and Glaucoma Services Kanjirampara, Opposite Indian Oil Petrol Pump, Trivandrum, Kerala, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Kasturi N, Jacob N, Jossy A, Chakrabarti A. Emerging innovations in cataract surgery. Delhi J Ophthalmol 2022;32:61-71. Emerging Innovations in Cataract Surgery Nirupama Kasturi1 , Ninan Jacob1 , Ajax Jossy1 , Arup Chakrabarti2 1 Department of Ophthalmology, Ophthalmology JIPMER Pondicherry, 2 Department of Ophthalmology, Chakrabarti Eye Care Centre, Trivandrum, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_83_23 Submitted: 24‑Dec‑2022 Accepted: 17‑Jan‑2023 Published: 31-May-2023 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow 61

Innovations In Improving Refractive Outcome of Cataract Surgery IOL power calculation formulae Several generations of IOL power formulae have evolved, resulting in vastly improved accuracy of post-operative refractive prediction. The regression formulae have been surpassed by those using ray tracing and artificial intelligence. Although they differ little in predicted optimal IOL power in eyes with average axial lengths, some are more accurate than others for lengths outside the mean. Web-based online calculators like the OcularMD Post-LASIK IOL Calculator (iol.OcularMD. com) and the ASCRS IOL Calculator (iol.ascrs. org) combine all the high-quality third and fourth-generation formulae with a Toric IOL calculator. 4,5The surgeon can use one or a combination of formulas for IOL power calculation to achieve optimum results. It is also easy to update and track postoperative outcomes.6 Intraoperative aberrometry These aberrometers are attached to the operating microscope and provide real-time intraoperative refractive information to increase the precision and accuracy of IOL selection. Useful under aphakic and pseudo-phakic conditions after removal of a cataractous lens in normal eyes, post-refractive surgery eyes, and post-radial keratotomy eyes [Figure 1a]. Also aids surgeons in selecting the correct axis for toric IOLs and placement of limbal relaxing incisions (LRIs) for astigmatism correction. The first commercially available intraoperative wavefront aberrometer was the ORange (Wave Tec Vision Systems Inc, Aliso, CA), which was later updated to the Optiwave Refractive Analysis (ORA) system (Alcon). Figure 1: (A)Intraoperative aberrometer and (B) Optical coherence tomography in cataract surgery Figure 2: Pupil expanders. (A) Malyugin ring (B) B-Hex pupil expander (C) Assia pupil expander (D) Visitec i-ring 62 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

HOLOS is another such device.7 The devices project light onto the retina, and the reflected images pass through the optical system of the eye, distorting its wavefront, which is subsequently analyzed according to optical and mathematical principles proprietary to the device. The ORA analyses and combines data from the central 4 mm optical zone with a dynamic range of – 5.00 to + 20.00 D and an accuracy of ± 0.30 D. ORA takes into account parameters such as posterior corneal astigmatism and higher-order aberrations, allowing the surgeon to confirm or revise the IOL power chosen according to preoperative biometry. The limitations are that it has a learning curve and prolongs surgical time. Figure 3: Zepto-capsulorhexis ring for precision pulse capsulotomy Figure 4: Femtosecond laser-assisted cataract surgery for corneal incisions, capsulorhexis and nuclear fragmentation Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 63

Biometry of the eye can be affected by patient factors (such as eyelid squeezing, eye motion, healing), surgical equipment (such as the eyelid speculum or use of certain ophthalmic viscosurgical devices), or intraoperative manipulation (such as stromal hydration) AS-OCT in cataract surgery It can be used for pre-operative characterization of dry eye by quantifying tear film thickness and tear film meniscus, calculation of IOL power, anterior segment measurements like WTW diameter, Sulcus diameter, angle-to-angle distance, etc. Intraoperative in-vivo assessment of clear corneal wound architecture, lens position, iris boundaries, iridocorneal angle, sulcus placement of phakic IOL and ciliary body is possible along with post-operative evaluation of IOL intraocular stability, assessment of post-cataract LASIK interfacial fluid, reliable measurements of ACD, cornea to IOL distances, iridocorneal angles and IOL tilt, capsular closure, and opacification [Figure 1b].8,9 Femtosecond laser-assisted cataract surgery (FLACS) First presented in 2008 by Nagy et al. and received FDA approval in 2010. The femtosecond laser is a near-infrared laser of 1053nm wavelength, and the femtosecond pulse duration (10-15S) uses ultrashort pulse duration and limits the collateral damage to surrounding tissues [Figure 4]. FLACS makes many steps of phacoemulsification a machine-driven, no-touch procedure and removes the surgeon factor to an extent from the outcome.10 It can be used to create self-sealing precise corneal incisions that are stable, safe, and limbal relaxing incisions for treating astigmatism. A well-centered circular capsulotomy and various nuclear fragmentation patterns can be used to easily fragment the nucleus as well as to soften it. FLACS has been proven useful in cases with a shallow anterior chamber, endothelial loss, white or dense cataracts, and subluxated cataracts.10,11 It cannot be performed in an eye with significant corneal scarring. Capsular block syndrome with nucleus drop can occur if intralenticular gas released from femtosecond laser application is not released before proceeding Figure 5: Zeiss Cataract suite for markerless alignment of toric IOLs Figure 6: 3D visualization systems A. Leica TrueVision and B. Alcon Ngenuity 64 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

with hydrodissection. Cortex aspiration may be more difficult, and risk of iris injury in cases with a small pupil. Innovations In Ocular Anaesthesia As cataract surgery techniques have advanced, the incision size has decreased, the need for iris manipulation has diminished, and operative time has lessened, resulting in a decrease in the need for complete akinesia and intensity of iris and ciliary body sensory block. For manual small incision cataract surgery, anterior subtenon anesthesia is preferred over the peribulbar block. Topical and intracameral anesthesia can provide adequate anterior segment anesthesia for noncomplex phacoemulsification with proper patient selection. Avoids the systemic and ocular risks seen in other blocks and allows quick visual recovery. Agents available are Tetracaine 0.5% drops, Tetravisc 0.5% gel (Ocusoft, Richmond, TX), Lidocaine 2% jelly, Xylocaine 4% (AstraZeneca, Wilmington, DE), Bupivacaine 0.75%. Lidocaine gel- more viscous; Tetravisc- intermediate viscosity (spreads like a liquid drop and coats like a gel). Topical anesthesia alone may not provide adequate iris and ciliary body anesthesia. (scleral sutured posterior chamber lens, pupil expansion device, or iris stretching) Therefore, many surgeons will supplement with intracameral 1% non-preserved lidocaine.12 Innovations In Ovd The introduction of Healon 5 (Advanced Medical Optics) has revolutionized the classification of OVDs. The newer generation of viscoelastic displays some features of dispersive substances but may be highly viscous and cohesive in other conditions, known as viscoadaptivity. Steve Archinoff described the ultimate soft shell technique, tri-soft shell technique, and soft shell bridge techniques using dispersive, viscoadaptive OVDs and balanced salt solution for safer surgery in eyes with endothelial loss, floppy iris, or zonulysis.13 Viscoanaesthesia combines a viscoelastic substance and lidocaine (VisThesia, Novartis). Innovations In Capsulorhexis Techniques The creation of perfectly centered, adequate-sized (5–5.5 mm) circular curvilinear capsulorhexis (CCC) is a very important step of modern phacoemulsification surgery. The needle cystotome is outshined by Utrata capsulorhexis forceps, Figure 7: Intra-operative image showing Heads-up cataract surgery Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 65

Microincision capsulorhexis forceps, Fugo/Plasma Blade for capsulorhexis, Femtosecond laser, and Zepto nano-pulse precision capsulotomy. Microincision Capsulorhexis Forceps They are forceps that allow surgeons to perform the procedure through a 20-22G side port incision. Useful in pediatric and posterior capsulorhexis and other intraocular manipulations during cataract surgery. Fugo/Plasma Blade For Capsulorhexis Invented by Richard J Fugo and was first approved by the FDA in 2000.12 It is a batterypowered, solid-state system that focuses electromagnetic energy into a thin filament (thinner than a human hair) to create a plasma blade capable of cutting biological tissue. It is helpful in cases with weak zonules, dense membranes, or small pupils, such as in IFIS, and can be performed beneath a P.K. graft with no post-operative graft decompensation. Femtolaser Assisted Rhexis The continuous curvilinear capsulorhexis can now be made as a centered circular capsulotomy (CCC) with predictable size, circular shape, centration, and accuracy. This was possible in only 10% of manual CCC.14 FLACS CCC can translate into better IOL centration, the ability to ensure accurate 360-degree coverage of the IOL optic, and achieve the desired 0.5-mm coverage of the optic along with less IOL tilt. Tilt, improper docking, corneal folds, and imaging or programming errors can cause decentred capsulotomy or partial capsulotomy.15 Zepto-Rhexis A novel capsulotomy method and technology called precision pulse capsulotomy (PPC) has been developed by Mynosys Cellular Devices, Fremont, Calif., USA [Figure 3]. The trade name “Zepto” received FDA clearance in June 2017 and is currently supplied in India by Care Group, Vadodara, India.16 Electrical nano pulses are delivered to a disposable handpiece with a soft collapsible tip and circular nitinol (Nickel-Titanium) cutting element, which is converted into mechanical cutting energy to create a 360-degree capsulotomy. A similar product still in the pre-clinical development stages is the Aperture CTC, which is also a thermal device that creates capsulotomy with heating. A key difference from the Zepto is that the tip is made from stainless steel and does not require suction. Small size, relatively inexpensive, and disposable capsulotomy device. Independent of pupil size, corneal clarity, or lens density. Very useful in white cataracts, small pupils, subluxated cataracts, and infantile cataracts, where a successful capsulorhexis is difficult.15 The Zepto nano-pulse capsulotomy system is significantly cheaper, results in a stronger capsulotomy, and reduces overall surgical time when compared to FLACS. Capsulaser The laser device attached to the bottom of the operating microscope creates a capsular opening in 1 second, following staining with trypan blue, and the capsular opening ranges from 4.5 to 6.5 mm.17 Innovations In The Management Of Small Pupil Advances In Pharmacological Pupil Expansion: Epi-Shugarcaine is a combined intracameral use of mydriatic agent (buffered lidocaine) and local anesthetic (epinephrine), pioneered by Sugar in 2006. Mydrane/Phenocaine is a combination of tropicamide (0.02%), phenylephrine (0.31%), and lidocaine (1%). Omidria is a combination of phenylephrine (1.0%) and ketorolac injection (0.3%) added to the irrigation solution, which also prevents the pupil from constricting and reduces postoperative ocular pain.18 Mechanical Pupil Expanders: Iris hooks have been surpassed by novel pupil expanders like the Assia pupil expander, Malyugin ring, Visitec i-ring and B-Hex pupil expander, Morcher pupil dilator, Milvella Perfect Pupil, Graether 2000 pupil expander, Oasis iris expander, and Xpand NT iris speculum [Figure 2]. Assia pupil expander is a pair of scissor-like disposable devices with blunt, rounded tips and an external spring mechanism. They are inserted through 1.1-mm side-port incisions located opposite to each other with specially designed forceps. After releasing the forceps, the device expands, hooking the iris with both curved tips. The resultant pupil shape is square or slightly trapezoidal; however, compared to the iris hooks, the number of incisions necessary to achieve pupil expansion is limited to two rather than four.19 The malyugin ring is a square foldable device made of polypropylene. The one-piece planar design with a thin profile features four circular curls at equidistant points on the ring, making it easier and safer to manipulate inside the eye. The latter is manufactured in two sizes – 6.25 mm and 7.0 mm in diameter, particularly useful for severe IFIS cases.19 Malyugin ring v 2.0 is made from 5.0 polypropylene and implanted through a 2.0mm incision. The ring is more flexible and more potent and creates perfectly round pupils approximately 6mm in size. Visitec I-ring pupil expander is made of soft polyurethane, creates a circular opening 6.3 mm in diameter, and is assembled with an injector to insert and remove it.20 Four corners of the device make four channels that hold the iris in place and add to the device’s stability during the surgical procedure. B-hex pupil expander is a third-generation Bhattacharjee Ring, a flexible jointless hexagonal plastic (Polyimide) ring with a 0.075 mm profile having notches and flanges disposed of in a single plane.21 Each disposable 6.5 mm B-HEX provides a 5.5 mm expanded pupil. The flexible notches allow maneuverability while resilient flanges resist buckling under the compressive force of the non dilating pupil. The planar structure makes the device extremely thin, providing the advantage of implanting through the 0.9 mm incision.20 Innovations In Phacoemulsification Machines And Techniques Phacomachines The sovereign system with Whitestar Technology (Advanced Medical Optics) transforms traditional ultrasound into digitally modulated phacoemulsification. Ultrapulse mode modulates the delivery of energy by manipulating both the duration and the frequency of ultrasonic vibrations. The primary advantage 66 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

is that it lessens thermal wound damage while maintaining the efficient cutting ability and reducing post-occlusion surges.21 Nuclear fragments are drawn safely and efficiently to the phaco tip in a phenomenon described as “magnetic followability.” AMO’s Whitestar Signature: Fusion Fluidics (Abbott) features the Fusion Fluidics, with the CASE (chamber stabilization environment) system and both peristaltic and venturi pumps. The surgeon can decide which system to use during the different parts of the surgery, using the foot pedal on the fly to engage peristaltic or venturi aspiration.22 Bausch & Lomb: Millennium Advanced Flow System (AFS) is the first peristaltic system to offer a selectable range of flow-based efficiency settings that increase responsiveness to vacuum-based performance while maintaining fluidic stability. Gives cataract surgeons precise and simultaneous control of vacuum limit, flow rate, and phaco power for unsurpassed intraoperative control.23,24 Specific features of this machine include selectable responsiveness that matches a variety of surgical techniques, enhanced surge protection even at high flow rates for better chamber stability, and precise and efficient performance at all vacuum levels. Bausch & Lomb: Stellaris-Stable Chamber Fluidics is a vacuum-control-based system that allows the surgeon to control the vacuum at the tip of the device during phacoemulsification, as well as irrigation and aspiration, using the foot pedal to modulate the vacuum level.25 During phaco, if occlusion occurs, the surgeon can reduce the vacuum by lifting the pedal, effectively preventing the big post-occlusion. It also features the Dual Linear foot pedal, which allows the surgeon to manage two parameters with the foot pedal.26 Alcon Infiniti Vision System is the world’s first tri-modal surgical instrument for cataract removal, which allows surgeons to choose from three different methods of removing a cataract.25 It features revolutionary fluidics and unique trimodal energy delivery options using AquaLase Liquefaction Device and NeoSoniX handpieces. The Aqualase technology uses warm pulses of balanced salt solution at 570 generated by electrodes in the handpiece. There is liquefaction of the lens material without the need for mechanical energy. This reduces corneal endothelial damage but is useful only in soft cataracts.27 The torsional handpiece (Ozil tip) can be programmed to deliver a combined traditional and torsional oscillation. The tip is angled and tapered so that the distal end is wider than the shaft, which allows shearing off nuclear pieces without repelling them, thus eliminating “chatter.”28 The decrease in thermal effects is due to the fact that the amount of energy being released at the tip is much greater than the amount of heat being created at the incision. The shaft of the torsional handpiece oscillates, and the oscillatory motion is translated to side-to-side movement at the tip. Alcon Centurion Vision system features Active fluidics technology, which is designed to maintain the target pressure inside the eye, provide greater anterior chamber stability, and reduce surge due to occlusion breaks. A bag of fluid is inserted into the machine and acted upon by pressure plates that are able to change the pressure in the bag very rapidly in response to feedback from sensors in both the irrigation and aspiration paths within the cassette. There’s also a pressure sensor on the bag itself. Active Sentry handpiece measures IOP very near the tip, eliminating that millisecond delay in adjusting the fluidics. INTREPID Hybrid Tip: has a polymer end with no sharp or metal edges.29 Phacoemulsification can be performed closer to the capsule and with higher flow and vacuum levels with reduced risk of capsular rupture. Another factor that sets the Centurion apart is its non-traditional peristaltic-style pump which, in effect, acts as two pumps pulling in parallel from the same piece of tubing. Twice the flow rate is achieved with a single pump, more than enough to overcome the resistance of the Centurion’s smaller tubing (which helps to minimize occlusion-break surge). The two pumps are configured to be out of phase with each other, which cancels out the small pulsations that a peristaltic pump always produces.30 Johnson & Johnson Vision White star signature Pro with active fluidics using both peristaltic and venturi pumps. Ellips FX handpiece with transverse motion. The Cataract Analysis and Settings Application (CASA): delivers a practice-eye-level view with mobile analytics and case insights. High-Definition Surgical Media Center (HD-SMC): for recording cases in high resolution to review and refine technique. Advanced Linear Pedal with wireless control.31 Staar Sonic Wave phacoemulsification system was the first phacoemulsification machine to incorporate sonic energy (40–400 Hz) as a possible alternative to conventional ultrasound. There is a total absence of thermal energy with no cavitational energy.32 Methods for Suppression of Surge Increasing inflow: Air Pump Forced Infusion (Accurus). The amount of fluid can be controlled independently of the bottle height, preventing surge and its consequences. The continuous maintenance of the anterior chamber allows the surgeon to freely manipulate the instruments and tissues inside the eye. The positive pressure creates a tense zonule and a firm capsular bag, facilitating the chop maneuvers. The endothelium is pushed forward, while the posterior capsule is pushed back. Decreasing outflow: The cruise control device developed by STAAR has a filter between the phaco handpiece and aspiration tubing that captures nuclear material. Enhances the safety and efficiency of phaco procedures by eliminating surges and stabilizing the anterior chamber. Newer tips with smaller bores and outflow constriction of 500-600 micron size decrease the amount of fluid aspirated from the anterior chamber. This increases the safety margin while using a higher vacuum and reduces the likely hood of a surge. Normal-sized tips (19/20 G) with an outflow constriction at the neck also decrease the fluid outflow but are more likely to get blocked by lens particles. Microprocessor controlled fluidics sample vacuum and flow parameters 50 times a second, creating a “virtual” anterior Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 67

chamber model. At the moment of a surge, the machine computer senses the increase in flow and instantaneously slows or reverses the pump to stop surge production. Optikon ACS3 surge suppression device is connected between the infusion bottle tubing and the irrigating sleeve. The diaphragm of the ASC3 device acts like a balloon and holds reserve irrigating fluid which is utilized in case of a surge. Aspiration Bypass Stabilizer (ABS) Microtips (Alcon) have 0.175 mm holes drilled in the shaft of the needle. During occlusion, the hole provides for a continuous alternate fluid flow. A dual Linear Footswitch is programmed to separate both the flow and vacuum from power. This way, flow or vacuum can be lowered before the emulsification of an occluding fragment begins. Phaco Techniques High vacuum chopping techniques for nuclear fragmentation are preferred over low vacuum sculpting methods like the divide and conquer of yesteryears because the modern phaco machines’ less compliant tubing and fluidic circuits tend to collapse less under a high-vacuum load. Mics Phaco (Micro Incision Cataract Surgery) Micro incision cataract surgery utilizes incisions ranging in size from 1.8 mm to 2.4 mm vs. 2.7 to 3.2 mm for traditional surgery, reducing the potential for surgically induced astigmatism, less leakage from the incisions, and a quicker recovery.33 Coaxial MICS No significant changes to the surgical technique from traditional coaxial phaco except that the phaco needle is of small diameter, and incisions of less than 1.5 mm are typically used to insert the needle into the anterior chamber. There is an adjustment to the fluidic parameters of the phaco machine. The Phaconit (using a 0.9mm incision) was introduced by Dr. Amar Agarwal.34 Bimanual MICS Bimanual phacoemulsification is different from traditional phacoemulsification because the irrigating and aspirating functions of the phaco handpiece are separated into two different handpieces. The sleeveless phaco tip enters through a primary incision less than 2 mm, and a second incision accommodates the irrigating chopper tool.35 Advantages of Bimanual MICS include smaller incisions provide a more stable anterior chamber during the procedure. Extremely useful in eyes with microcornea, post-radial-keratotomy, high myopia, and eyes requiring refractive lens exchange. The limitation of small incisions is twofold: the inability to insert a high-quality intraocular lens (IOL) implant as well as to maintain adequate fluid flow through the smaller incision. In a 2005 survey, 78% of cataract surgeons believed that bimanual phaco could be potentially useful, but only if IOL technology advances sufficiently to take advantage of smaller incision sizes. Almost one-quarter of respondents said bimanual phaco is a difficult procedure with no obvious advantages. Dropless cataract surgery Introduced due to the difficulties in instilling drops and their effect on patient compliance. TriMoxi: single-use suspension containing 15 mg/mL of triamcinolone and 1 mg/mL of moxifloxacin and TrimoxiVanc: adds 10 mg/mL of vancomycin to the compound. At the end of the surgery, 0.2 mL of the suspension is introduced into the posterior chamber through a trans-zonular injection. Disadvantage: visible drug affects the vision for up to 3-7 days after surgery. 36 Pure phaco: phacoemulsification without OVD This technique was developed to negate the undesirable effects of OVDs like high IOP, TASS, and capsular bag distension syndrome. The procedure uses an A.C. maintainer to control IOP during phacoemulsification, avoidance of hydrodissection and incision, and hydroimplantation of foldable IOL. It cannot be used in cataract surgery beyond grade III because the endothelium remains unprotected.37 3-D Visualization System - Heads-Up Surgery In Ophthalmology NGENUITY(Alcon) It is an advancement in the operating room that allows the surgeon a 3-dimensional view the eye in real-time during intraocular surgery [Figures 6 & 7].38 For traditional cataract surgery, the surgeon sits next to the patient and looks through the eyepieces of an operating microscope, which provides a lighted and magnified view of the eye during surgery. It combines several breakthroughs in electronics to give the surgeon a unique 3-dimensional view of the eye during surgery. The visualization system consists of a twin sensor and highdefinition camera that captures the images and sends the signal through an ultra-high-speed image processor to a 3-D, Ultra High Definition monitor. The surgeon can view an enlarged eye on a large screen(55 inches), with twice the magnification and five times more depth of focus than a traditional operating microscope. The camera can be easily rotated to comfortably allow surgery for patients who cannot lie completely flat due to neck fusion, breathing difficulties, etc. It is also a great tool for teaching and training. This new system’s comfortable and ergonomic heads-up surgical position promotes better posture and surgeon health.39 Truevision Smart 3D Leica Microsystems and TrueVision® have collaborated to integrate TrueVision Smart 3D surgical visualization and recording into the Leica surgical microscopes.40 Greatly enhance microsurgery education, providing all staff and students with the same 3D view as the surgeon. As the TrueVision Smart 3D is built in, set-up time is minimized, and OR space is freed up. 3D functions are controlled directly via the microscope controls, avoiding interruption to workflow. Zeiss Artevo 800 A first-of-its-kind digital microscope can be used as an imaging, information, and teaching tool in cataract, corneal, retinal, and glaucoma surgery. The DigitalOptics™ technology 68 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

produces a stereoscopic 3D image viewed using passive polarized glasses.47 Monitor provides viewers with a natural color impression of the surgical field and can be positioned anywhere in the operating room Data, such as intraoperative OCT, cataract assistance functions, and phaco vitrectomy values, as well as patient information and operating room settings, can be overlaid onto the active image without blocking the surgeon’s view of the eye. If the surgeon wants to use oculars at any point, a sterile knob can redirect a portion of the light to them. The screen remains in operation, so other people in the room continue to see what the surgeon sees. The device transmits 25 percent more light than conventional optics, so surgery can be performed at a reduced light intensity. Other heads-up 3D visualization systems in ophthalmology include the Sony HD Medical Display system (Sony, Tokyo, Japan), MKC 700 HD, and CFA 3DL1 (Ikegami, Tokyo, Japan). Head-Mounted Systems (Hms) In Ophthalmology The Haag-Streit Surgical microscope HS Hi-R NEO 900 (HaagStreit Surgical GmbH, Wedel, Germany) is connected to the Sony Head-Mounted System HMS-3000 MT device. [40] It consists of an image processing unit, a head-mounted display that provides a stereoscopic visualization from the imaging system, and a 3D color video display of images from the 3D, full-HD surgical camera system. It can connect a second headmounted monitor, giving other theater staff a simultaneous 3D view. Depth perception inside the HMS device requires different images for the left and right eyes. The head-mounted system differs from conventional 3D systems by showing two simultaneous pictures for each eye. Other head-mounted systems include Avegant Glyph retinal projection system (Avegant Corp., Belmont, CA, USA) and Clarity™ (Beyeonics Surgical, Haifa, Israel). Innovations In Intraocular Lenses The technology behind intraocular lenses has evolved in recent years to offer an expanded number of IOL options for patients requiring cataract surgery. Acrylic preloaded injectable foldable IOLs are replacing PMMA Rigid lenses. The preloaded insertion systems are single-use disposable devices, requiring small incision size, reduced optic size, reduced surgical time, elimination of handling and misloading the IOL, and are associated with less risk of endophthalmitis.41 Aspheric IOLs reduce spherical aberrations and provide better image quality and contrast sensitivity (C.S.). Aberrationcontrol aspherical IOLs induce negative S.A. to compensate for the positive S.A. of the cornea. Reducing overall levels of S.A. can result in improved C.S. and V.A. These aberrationcontrol lenses correct a specific amount of S.A. despite varying levels of corneal aberration. Aberration-control aspherical IOLs depend on the centration of the IOL in relation to the visual axis. Aberration-neutral aspherical IOLs are designed to be aberration-free. They do not introduce any aberration into the eye but equally do not compensate for the positive S.A. of the cornea. These IOLs are affected less by centration in comparison with aberration-control aspherical IOLs. Toric IOLs allow patients to correct corneal astigmatism at the time of cataract surgery and achieve spectacle independence for distance vision. The exact alignment of the Toric IOL at the calculated alignment axis is necessary to achieve effective astigmatism correction. Manual axis marking using instruments and slit lamps has been superseded by Image-guided systems Like the Zeiss Callisto eye, VERION, and Leica truevision surgical system [Figure 5]. It involves the superimposition of preoperative measurements and intraoperative images to provide a guide for toric IOL alignment.50 ZEISS Cataract Suite is an integrated platform that includes the CALLISTO eye, the IOLMaster 500 or 700, FORUM, and the OPMI LUMERA family of microscopes. It allows for markerless and more precise intraoperative toric IOL alignment. These computerassisted surgery techniques also help with incision placement and size, limbal relaxing incisions, and capsulorrhexis size and placement. Alcon’s Cataract Refractive Suite consists of Verion Image Guided System, LenSx Laser, Luxor LX3 with Q-Vue Ophthalmic Microscope, and Centurion Vision System. In addition to imaging the eye, the Verion Image Guided System can be used by surgeons to plan surgery and guide the procedure. Verion’s reference unit performs necessary measurements of the eye in a single step, and the planning unit performs the IOL calculation by directly importing the data from the reference unit. Information can then be passed on to the LenSx laser and the ophthalmic microscope. Multifocal IOLs Multifocal IOLs are designed with concentric rings which can focus light rays from both distances and near simultaneously. Refractive multifocal IOLs have several concentric zones that differ in curvature, creating the varying refractive powers. Diffractive multifocal IOLs have concentric rings across their entire surface with discrete borders, which makes a diffraction pattern. Therefore, these lenses are pupil-independent, and an equal light split is maintained regardless of pupil size. These lenses create two definitive peaks at two specific focal distances, creating two precise, clear images. Patients with a multifocal IOL more often report halos, glare, and reduced contrast than with a monofocal IOL. Extended range of vision (EROV) / extended depth of focus (EDOF) IOL TECNIS Symfony IOL (Abbott) is the first FDA-approved lens of its class. Others are AT LARA(ZEISS). The IOL has a biconvex wavefront-designed anterior aspheric surface and a posterior achromatic diffractive surface with an echelette design. This proprietary format creates an achromatic diffractive pattern that elongates a single focal point and compensates for the chromatic aberration of the cornea. With a diffractive optic, the extended foci allow for nearly all light to be transmitted through the IOL, with the reduction of chromatic aberrations.42 50% less light loss, less glare, and haloes than traditional Diffractive multifocal IOLS. Alcon Vivity is a nondiffractive EDOF IOL that delivers an extended range of vision while maintaining a monofocal-like visual profile. Johnson Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 69

& Johnson TECHNIS Eyehance monofocal IOL is in the pipeline, intended to extend the depth of focus from distance to intermediate vision. Small-aperture IOLs also extend the depth of focus. These are especially effective in post-LASIK, post-RK eyes, and irregular corneal astigmatism. The IC-8 IOL (AcuFocus) is a single-piece hydrophobic monofocal IOL that works similarly to Kamra corneal inlay and uses the pinhole principle to increase the depth of focus to about 3D. The XtraFocus Pinhole implant (Morcher) designed by Trinidade et al. is another small-aperture sulcus IOL made of black acrylic with a central pinhole. SEGMENTED BIFOCAL and TRIFOCAL IOLs The Mplus, Mplus X (Oculentis), and SBL-3 (Lenstec) are rotationally asymmetric segmented bifocal IOLs with sectorshaped near vision segment giving two focus zones for better depth of focus. PanOptix Trifocal IOL (Alcon) is the latest addition to the presbyopia mitigation IOL landscape. It has three focal points near 40 cm (16 inches), intermediate at 60 cm (24 inches), and distance. The lens allows 88% of light energy to be utilized at a 3-mm pupil size, with 50% directed to distance, 25% to intermediate, and 25% to near. It has a 4.5-mm diffractive zone that is designed to be less dependent on lighting conditions or pupil size. The AT Lisa(Zeiss) and Finevision (PhysIOL), Alsafit(Alsanza), and Acriva Reviol(VSY Biotech) are other trifocal IOLs. HYBRID IOLs like TECHNIS Synergy combine the best features of existing diffractive multifocal and EDOF technology, surpassing the visual gaps and delivering a potentially better visual continuity than trifocal lenses. Accommodating IOLs: These are IOLs that afford both distant and reasonable near vision as well with the help of haptics, which can flex, materials that expand and contract within the capsule bag along with the ciliary body contraction, to and fro piston like the motion of the anterior vitreous. The function of the accommodative IOL would greatly depend on the strength of ciliary muscle contraction, which may be waning off with age, and capsular fibrosis and opacification may hamper its function. Long-term studies are necessary to validate the clinical outcomes of these lenses.42 Thinoptx rollable IOL is an ultra-thin, hydrophilic acrylic IOL designed for in-the-bag placement after micro incisional cataract surgery, which can be rolled and inserted through an incision of 1.4 mm. Lost popularity due to increased rates of PCO and haloes. Femtis IOL is the first IOL designed for Femto laser-assisted cataract surgery with a grooved edge to anchor in the perfectly circular capsulorhexis. It offers stable IOL centration, predictable, effective lens position, and better refractive outcomes. Light-adjustable IOLS provides a safe, non-invasive, post-operative refractive adjustment with the light delivery device (LDD) of the selected wavelength, spatial intensity profile, and diameter to produce a predictable change in the power of the LAL. Anti-dysphotopic IOL by Masket has a peripheral groove that fits into the margin of capsulorhexis. This helps to prevent dysphotopsia as the anterior capsule does not overlap over the IOL. Erie JC used ray-tracing diagrams and proposed a biconvex IOL design with a peripheral posterior concave surface which redirects the rays more anteriorly and illuminates a broader area of the retina, thereby eliminating the negative dysphotopsia. Gonzalo Munoz developed the pinhole iris-claw IOL, which comprises a black diaphragm with a central hole for the correction of positive dysphtopsia and photophobia. The pinhole effect minimizes the impact of corneal higherorder aberrations on the quality of the retinal image. Newer improved IOL designs that compensate for the misalignment of the optical and visual axis may help address this issue further.43 Miscellaneous Innovations miLoop lens fragmentation device The miLOOP® from ZEISS is a microinterventional lens fragmentation device that is designed to remove the challenges of hard cataracts. Using micro-thin super-elastic, self-expanding nitinol filament technology, the ZEISS miLOOP allows cataract surgeons to achieve zero-energy lens fragmentation for any grade cataract. It reduces the amount of ultrasound energy and adequate phaco time required and also helps to minimize the stress on zonules and capsules during the surgery.44 Preloaded CTR A capsule tension ring (CTR) is a highly ¬exible clear PMMA (polymethylmethacrylate) ring used to expand and stabilize the capsular bag to facilitate a safe IOL implantation and maintain a good IOL centration in eyes with zonular dehiscence.56 Preloaded rings are now available in the market, which is easy and safe to insert. Iris Prosthesis The Morcher endocapsular implant, Ophtec endocapsular implant, and Aniridia implant are artificial iris implants that can be used in patients with iris defects, thus reducing photophobia and poor contrast sensitivity.57 Conclusion Several innovations in cataract surgery, including technology, instrumentation, and surgical techniques, have improved its safety and efficacy over the decades. These can help the surgeon efficiently perform challenging cases and improve postoperative outcomes. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. 70 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

References 1. Roger F Steinert, cataract surgery, 4th edition. Elsevier 2022. 2. Shah TD, Shah RT, Ranpara KH. Update and understanding of optical biometer. Glob J Cataract Surg Res Ophthalmol 2022;1:26-35. 3. Findl O, Drexler W, Menapace R, Kiss B, Hitzenberger CK, Fercher AF. Optical biometry in cataract surgery. Dev Ophthalmol. 2002;34:131-40. 4. Ventura BV, Ventura MC, Wang L, Koch DD, Weikert MP. Comparison of biometry and intraocular lens power calculation performed by a new optical biometry device and a reference biometer. J Cataract Refract Surg. 2017;43:74-79. 5. Nazm N, Chakrabarti A. Update on optical biometry and intraocular lens power calculation. TNOA J Ophthalmic Sci.Res 2017;55:196-210. 6. Ashwin PT, Shah S, Wolffsohn JS. Advances in cataract surgery. Clin Exp Optom. 2009;92:333-42. 7. Wiley WF, Bafna S. Intra-operative aberrometry guided cataract surgery. International Ophthalmology Clinics. 2011;51:119-129. 8. Nguyen P, Chopra V. Applications of optical coherence tomography in cataract surgery. Curr Opin Ophthalmol. 2013;24:47-52. 9. Titiyal JS, Kaur M, Falera R. Intraoperative optical coherence tomography in anterior segment surgeries. Indian J Ophthalmol 2017;65:116-21. 10. Agarwal A, Jacob S. Current and effective advantages of Femto phacoemulsification. Curr Opin Ophthalmol. 2017;28:49-57. 11. Kanclerz P, Alio J.L. The benefits and drawbacks of femtosecond laserassisted cataract surgery. Eur J Ophthalmol. 2020:1120672120922448. 12. Rom Kandavel. Local anesthesia for cataract surgery. Chapter 1. In Achieving excellence in cataract surgery: A step by step approach. D. Michael Colvard. 2009. US;p1-10. 13. Arshinoff, Steve A, Norman, Richard B. Tri-soft shell technique. Journal of Cataract & Refractive Surgery 39:p 1196-1203 14. Chang JS, Chen IN, Chan WM, Ng JC, Chan VK, Law AK, et al. Initial evaluation of a femtosecond laser system in cataract surgery. J Cataract Refract Surg. 2014;40:29–36. 15. Daya S, Chee SP, Ti SE, Packard R, Mordaunt D.H. Comparison of anterior capsulotomy techniques: continuous curvilinear capsulorhexis, femtosecond laser-assisted capsulotomy, and selective laser capsulotomy. Br J Ophthalmol. 2020;104:437-442. 16. Pandey SK, Sharma V. Zepto-rhexis: A new surgical technique of capsulorhexis using precision nano-pulse technology in difficult cataract cases. Indian J Ophthalmol. 2018;66:1165-1168. 17. Stodulka P, Packard R, Mordaunt D. Efficacy and safety of a new selective laser device to create anterior capsulotomies in cataract patients. J Cataract Refract Surg. 2019 ;45:601-607. 18. Lawuyi LE, Gurbaxani A. The clinical utility of new combination phenylephrine/ketorolac injection in cataract surgery. Clin Ophthalmol. 2015;9:1249-54. 19. Malyugin B. Cataract surgery in small pupils. Indian J Ophthalmol. 2017;65:1323-1328. 20. Bhattacharjee S. B-HEX pupil expander: Pupil expansion redefined. Indian J Ophthalmol. 2017;65:1407-1410. 21. Howard V. Gimbel, MD, FRCSC and Carlindo da Reitz Pereira, MD: Advances in phacoemulsification equipment. Opin Ophthalmol 2002, 13:30–32 22. Richard S. Hoffman, I. Howard Fine and Mark Packer: New phacoemulsification technology. Curr Opin Ophthalmol 16:38–43. 23. Shah PA, Yoo S. Innovations in phacoemulsification technology. Curr Opin Ophthalmol. 2007;18:23-6. 24. Hoffman RS, Fine IH, Packer M. New phacoemulsification technology. Curr Opin Ophthalmol. 2005;16:38-43. 25. Micheal J. Gallagher, MD, FRCOphth: cataract surgery recent advances. Contemporary ophthalmology 2007, vol 6. 26. Relan S, Dudhani A. Advances in phacoemulsification. Journal of Bombay Ophthalmologists Association 2005; 14: 26-7. 27. Hughes EH, Mellington FE, Whitefield LA. Aqualase for cataract extraction. Eye (Lond). 2007;21:191-4. 28. El-Moatassem Kotb AM, Gamil MM. Torsional mode phacoemulsification: effective, safe cataract surgery technique of the future. Middle East Afr J Ophthalmol. 2010;17:69-73. 29. Sabur H, Eroglu SA, Azarsiz SS. Efficacy of Balanced Torsional Phacoemulsification Tip for Cataract Surgery. J Curr Ophthalmol. 2022;34:74-79. 30. Gimbel HV, da Reitz Pereira C. Advances in phacoemulsification equipment. Curr Opin Ophthalmol. 2002;13:30-2. 31. Fishkind WJ. The phaco machine: analyzing new technology. Curr Opin Ophthalmol. 2013;24:41-6. 32. Fırat Helvacıoğlu, Sadık Şencan, Zeki Tunç, Celal Yeter. Torsional Phacoemulsification and Tip Selection.Turk J Ophthalmol 2014; 44: 392-5. 33. Assaf, A., El-Moatassem Kotb, A. Feasibility of bimanual microincision phacoemulsification in hard cataracts. Eye 21, 807–811 (2007). 34. Agarwal A, Agarwal A, et al. Phakonit: phacoemulsification through a 0.9 mm corneal incision. J Cataract Refract Surg. 2001,27:1548-1552. 35. Fu C, Chu N, Yu X, Yao K. Bimanual Microincision Cataract Surgery versus Coaxial Microincision Cataract Surgery: A Meta-Analysis of Randomized Controlled Trials and Cohort Studies. J Ophthalmol. 2017;2017:3737603. 36. Bardoloi N, Sarkar S, Pilania A, Das H. Efficacy and safety of dropless cataract surgery. Indian J Ophthalmol. 2020;68:1081-1085. 37. Bardoloi N, Sarkar S, Pilania A, Das H. Pure phaco: phacoemulsification without ophthalmic viscosurgical devices. J Cataract Refract Surg. 2020;46:174-178. 38. Devgan U. Surgical techniques in phacoemulsification. Curr Opin Ophthalmol. 2007;18:19-22. 39. Weinstock RJ. Operate with your head up. Cataract Refract Surg Today. 2011;8:66, 74 40. Weinstock RJ, Desai N. Heads up cataract surgery with the TrueVision 3D Display System. In: Garg A, Alio J.L., eds. Surgical Techniques in Ophthalmology—Cataract Surgery. New Dehli, India: Jaypee Medical Publishers; 2010:124–127. 41. Shekhar H, Sinha R. Newer Intraocular Lenses in Present Day Cataract Surgery. DJO 2013;24:108-113. 42. Micheal J. Gallagher. Cataract Surgery: Recent Advances. Contemporary ophthalmology.2007;6:1-6 43. Rupnik Z, Elekes Á, Vámosi P. Clinical experience with an antidysphotopic intraocular lens. Saudi J Ophthalmol. 2022;36:183-188. 44. Hu EH, Buie T, Jensen RJ, Wu D, Pamnani RD. Comparative Study of Safety Outcomes Following Nucleus Disassembly with and without the miLOOP Lens Fragmentation Device During Cataract Surgery. Clin Ophthalmol. 2022;16:2391-2401. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 71

Abstract Theme Section Introduction Strabismus surgery has evolved over time from being a cosmetic surgery aimed at personality development and correction of diplopia, to restoration of binocular vision and stereopsis – one of the biggest assets of human race which have helped established its supremacy. Also, unlike the instant gratification of a cataract surgery, successful surgical outcome of strabismus relies on a thorough understanding of its underlying principles and proper preoperative evaluation. The final goal of surgery is dependent upon free movement of the tissues after surgery, hence tissue handling should be such that the strength and leverage of the muscles is not disturbed. Normal tissue planes should be maintained so that a revision, if needed, is not difficult. Minimally invasive surgeries are common in all fields of medicine including ophthalmology. Some of these include micro incision cataract surgery (MICS), suture less vitrectomies, minimally invasive lid surgeries and micro invasive glaucoma surgery (MIGS) devices. Recently, Mojon1 propagated a new minimally invasive strabismus surgery (MISS) wherein two radial incisions nearly parallel to the horizontal rectus muscle, extending posteriorly from the upper and lower ends of the muscle-sclera insertion, are given. When compared to the limbal approach, this method was claimed to have less post-operative inflammation. However, it involves a trans-conjunctival technique of suturing, which is difficult to learn, is suitable only for small recessions and plications and only for age group of 14 - 40 years. A Park’s fornix incision about 8 mm from the limbus is equally good as it can be easily closed with two or three 8-0 vicryl sutures and yields cosmetically acceptable results. Modifications in horizontal recti surgery Double-breasting or plication is a procedure where a muscle is shortened without excising the muscle mass as is done for resection (Figure 1). This technique avoids slippage of the muscle and gives a chance for a revision surgery if needed. It can be used for medial rectus resection. A new modification in adjustable surgery is single-stage adjustable suture surgery (SSASS) wherein a hemi hang-back recession of the lateral Strabismus surgery is an ever-evolving branch with newer procedures being described to make it less invasive and preserve normal tissue anatomy as much as possible, while providing ocular alignment and restoring binocularity. These procedures include minimally invasive squint surgeries, modifications to conventional procedures such as plications instead of resections, mini-tenotomies and mini-plications, tucking procedures or tenoplication, use of adjustable sutures, synthetic expanders, Botulinum toxin, amniotic membrane transplants, muscle transplantation, and so on. These procedures have the advantages of minimal tissue damage, less surgical time, early rehabilitation and allow chances of re-adjustment or redo procedures later on. Though the described techniques are still evolving and have limited literature, they can be learnt by skilled surgeons and should be incorporated into mainstream strabismus surgery. Keywords: Strabismus, Minimally Invasive Strabismus Surgery, Mini-Tenotomy, Mini-Plication, Topical Anesthesia Address for correspondence: Pradeep Sharma, MD, FAMSEx-Professor, AIIMS Director Strabismus Pediatric and Neuro-Ophthalmology Services, Centre for Sight, Safdarjung Enclave, New Delhi, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Chaturvedi I, Sharma P. Surgical innovations in strabismus surgery – A brief review. Delhi J Ophthalmol 2022;32:72-7. Surgical Innovations in Strabismus Surgery – A Brief Review Isha Chaturvedi, Pradeep Sharma Department of Ophthalmology Centre for Sight Eye Institute, Dwarka, New Delhi, India, Department of Strabismus Pediatric and Neuro-Ophthalmology Services, Centre for Sight, New Delhi, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_84_23 Submitted: 12‑Nov‑2022 Accepted: 18‑Jan‑2023 Published: 31-May-2023 72 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

rectus (LR) is performed. After about 5 hours when the normal muscle tension is restored, an adjustment can be performed under intravenous sedation coupled with topical anaesthesia (no local or general anaesthesia). Figure 2 shows various techniques of adjustable suture surgery. At times, there is a near-distance disparity and lateral incomitance seen in horizontal strabismus. For a convergence excess esotropia, a Faden or posterior fixation suture can be added onto medial rectus (MR) recession. Here, the muscle is sutured posterior to its insertion, farther than the limit of its arc of contact. This shortens the lever arm drastically and reduces the action of the muscle in its field of action. If no recession is performed, there is no change in the length-tension relationship in the primary position. As can be seen in Figure 3a, Faden without recession causes no laxity of MR and so no change of ocular deviation in the primary position, but only a slight shortening of the lever arm as seen in Figure 3b. But in adduction, the lever arm is significantly shorter causing weaker adduction and progressively weaker in extreme adduction (Figure 3c). In divergence excess type of exotropia, Faden’s procedure is not that effective in LR muscle weakening. In such cases a combined LR resection-recession is done, known as the Scott procedure, which has the same effect as Faden if equal amount of resection and recession is done on the same muscle. The interesting part is that by using differential amounts of the resection and recession on the same muscle one may correct the deviation in the primary position as well the extra deviation in the lateral gaze for near distance disparity. For example, a 5 mm resection followed by 10 mm recession on the same LR muscle helps to correct the divergence excess for distance.2 Tackling the oblique muscles Surgery on oblique muscles is commonly done either in combination with horizontal muscle surgery as in A and V patterns or for correction of cyclo-vertical muscle problems like superior oblique palsy, double elevator palsy and so on. Contrary to old practice, inferior oblique (IO) myectomies and free superior oblique (SO) tenotomies are best avoided. For IO weakening, a pure recession without anteropositioning or with antero-positioning (if more anti-elevation effect is desired) can be done. One must remember that the anterior fibres of SO cause intorsion, and IO, extorsion. The posterior fibres of SO cause depression and abduction in downgaze and those of IO cause elevation and abduction in upgaze. Surgery on one group, sparing others weakens that function selectively. The most commonly done procedure for IO weakening is a modified Elliot and Nankin procedure as shown in Figure 4. In this method, the anterior end of IO is positioned at the lateral end of the inferior rectus insertion, with the posterior end being further down at 5 mm posteriorly. For more effect, the anterior end can be inserted about 1-2 mm anterior to the lateral end of the inferior rectus. This method weakens the elevation and abduction in downgaze. In total antero-positioning of IO also described by Elliot and Nankin3 the entire width of the muscle is re-inserted anterior to the inferior rectus (Figure 5). This weakens the elevator function almost totally and may produce some depression action. It is reserved for dissociated vertical deviations (DVD) with IO overaction. So in cases of DVD with IO overreaction this method may correct the overaction as well as have antielevation effect to counter the DVD. Weakening procedures of SO are used in pattern deviations with overacting superior obliques, Brown’s syndrome and as a part of torsional Kestenbaum surgery. The commonly done procedures are posterior tenectomy of superior oblique (PTSO), hang loose loop tenotomy, use of silicon expanders and translational recession of SO. In PTSO, after hooking the Figure 1: Double breasting or plication of the medial rectus muscle [From Strabismus Simplified (2nd ed., p. 214) by Sharma P, 2019. CBS Publishers & Distributors.] Figure 2: (a) – hemi hang-back recession, (b) – full hang-back recession, (c) – sliding-noose suture adjustment [From Strabismus Simplified (2nd ed., p. 211) by Sharma P, 2019. CBS Publishers & Distributors.] Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 73

SO, the anterior (1-2 mm width) fibres are spared and a wedge of the posterior fibres is excised (Figure 6). This selectively weakens the depression and abduction in downgaze, correcting the pattern deviations, without significantly affecting intorsion. For more severe overactions of the SO, a translational recession can be done. Here the muscle tendon is disinserted and reinserted 12 mm from the limbus and 6 mm from the nasal end of superior rectus. This procedure was described by Prieto-Diaz4 and it prevents the limitation of depression in abduction usually seen with anterior placement of SO. A better technique in cases of a tight SO as in Brown’s syndrome, a loop tenotomy may be performed. The muscle is disinserted, 2 double-armed 5-0 mersilene or ethibond sutures are passed through it, an intraoperative forced duction test (FDT) is performed so as to free the tight muscle fibres and then using a hang back loop technique, the tendon is re-inserted. Similarly, when using a silicon expander, the SO is transected and a piece of silicon band (2-2.5 mm wide and 5-8 mm long) is interposed between the cut ends of the tendon with the help of sutures (Figure 7). However, this has a risk of extrusion. Strengthening procedures on the IO are limited as it lacks a tendinous portion, hence resection cannot be performed. A selective strengthening can be done by disinserting the anterior half and advancing it 8 mm upwards from its actual insertion. For strengthening of SO, a tucking or tenoplication can be performed. The tendon is hooked and lifted to double fold over itself as shown in Figure 8. Normally a 4x4 mm double folding produces an 8 mm tuck which is enough for a 3+ overaction. One must do an intraoperative FDT to assess the tightness of the SO and prevent inducing Brown’s syndrome. Modified Harada-Ito procedure is a selective strengthening procedure for the intortion component of SO. Here, an anterior tenting of anterior fibres is done by securing them close to the temporal Figure 3: (a and b )– Faden without recession causes only a slight weakening in primary position with slight shortening of the lever arm lp, (c) – shorter lever arm la with weaker adduction [From Strabismus Simplified (2nd ed., p. 213) by Sharma P, 2019. CBS Publishers & Distributors.] Figure 4: Modified E and N’s antero-positioning at lateral border of inferior rectus [Image source: Dr Pradeep Sharma (2020, Sep 5). KGMU Eye lecture: Newer Procedures in Strabismus Surgery. YouTube [Video]. Accessed via https://youtu.be/x25Pf1LQIi4] Figure 5: Total antero-positioning of IO anterior to inferior rectus [Image source: Dr Pradeep Sharma (2020, Sep 5). KGMU Eye lecture: Newer Procedures in Strabismus Surgery. YouTube [Video]. Accessed via https://youtu.be/x25Pf1LQIi4] Figure 6: Posterior tenectomy of superior oblique sparing only anterior 1-2 mm fibres, posterior fibres cut in 3 steps viz. 1,2,3 [From Strabismus Simplified (2nd ed., p. 228) by Sharma P, 2019. CBS Publishers & Distributors.] 74 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

end of the superior rectus (Figure 9) or even advancing them towards the LR. Some new procedures involve periosteal fixation of the muscle to globe with the help of non-absorbable sutures like 5-0 mersilene passed sequentially through the MR or LR and adjacent periosteum. This has been used in 3rd nerve palsy to produce about 5-8 PD of esotropia. Evolution in transposition procedures Transpositioning of muscles is performed when the function of a muscle cannot be improved by any strengthening procedure so that adjacent muscles are transpositioned to improve the action of the paretic muscle.5 One such procedure is the adjustable cross action partial vertical rectus transposition (VRT) done for lateral rectus palsy. In a partial VRT, the temporal fibres of the vertical recti are separated and reinserted adjacent to the lateral recti. In cross action VRT as shown in Figure 10, the inferior rectus muscle is inserted close to the superior end and superior rectus close to the inferior end of the LR. This gives more vectorization of the forces. These can be inserted via adjustable sutures to have the desired amount of strengthening. In modified Nishida’s procedure, no disinsertion of the recti is done. Instead, posterior fixation sutures using 5-0 ethibond, are passed through these muscles and transfixed to sclera about 13 mm from the limbus, in order to get a torque effect. Another procedure for LR palsy is a Y-split combined with medial transposition of the LR muscle.6,7 A similar approach is useful in synergistic innervational downshoot (aberrant contraction of IR during adduction) where IR is transposed towards MR to correct the downshift as well as improve adduction8 The idea is to do a targeted muscle surgery where the misinnervation is identified and the misdirected muscle transposed to the correct side. Strabismus surgery under topical anaesthesia Wright described a mini-tenotomy to correct about 2-4 PD of deviation.9 Here, the central muscle tendon is grasped with the help of a tenotomy forceps which has slightly blunt teeth, and then cut with Westcott scissors, transconjunctivally (Figure 11). Post-operatively a central tendon cut of 3-4 mm is obtained while the poles of the muscle are left intact. For example, an esotropia of 4-6 PD can be treated with MR tenotomies. This procedure can be performed as a day-procedure to correct small-angle deviations in patients who may not want to wear prism spectacles or undergo standard strabismus surgery. Similarly, a mini-plication for rectus muscle tightening has been described10 wherein a Swan incision is made over the muscle insertion, the conjunctiva is dissected off the muscle belly, and the muscle grasped centrally about 5 mm from the insertion. Next, 6-0 vicryl suture is passed through the central 3-4 mm of the tendon about 5 mm posterior to the muscle insertion and tied in a square knot. This gives about 5-7 PD of correction. Though attractive, these procedures can be performed only in adults and these studies are limited by their small sample size and lack of long-term follow up. Adult strabismus is often more complex to treat than paediatric strabismus due to several factors. Firstly, incomitance and diplopia is more common. Secondly, the deviations are often small yet symptomatic and finally, torsional deviations are more frequently seen. In the face of increasing proportion of elderly population and associated morbidity, Pineles et al11 have described several techniques to manage some of these complex deviations. One such technique is posterior fixation of the rectus combined with an adjustable recession. Here, the muscle is disinserted and fixed to the sclera is done about 14- 18 mm from the limbus, depending on the specific muscle. A sliding noose suture tailored to the desired amount of recession, can be used to fix the muscle to sclera. The posterior fixation weakens the effect of the muscle in its field of action and the adjustable recession further titrates this effect in the primary gaze. This procedure is useful in incomitant strabismus. Selective tenotomy and plication of vertical recti is another technique described by the same authors for correction of horizontally incomitant vertical strabismus and cyclodeviations. A non-absorbable suture is passed through the Figure 7: Lengthening of superior oblique tendon using a silicon expander [Image source: Dr Pradeep Sharma (2020, Sep 5). KGMU Eye lecture: Newer Procedures in Strabismus Surgery. YouTube [Video]. Accessed via https://youtu.be/x25Pf1LQIi4] Figure 8: Tucking (full width) with a hook and muscle clamp (MC) followed by double folding of the SO [From Strabismus Simplified (2nd ed., p. 230) by Sharma P, 2019. CBS Publishers & Distributors.] Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 75

nasal or temporal half of the tendon which is then cauterized and disinserted with Westcott scissors. Then suture is then passed through the original insertion via slipknot for later readjustment. This procedure hangs back one pole of the muscle insertion while the central tendon is still attached, hence corrects only the horizontal incomitance of a vertical deviation rather than eliminate a hypertropia. A selective plication can also be performed similarly. These procedures have the advantages of later re-adjustment, relative sparing Figure 10: Cross action VRT technique [Image source: Dr Pradeep Sharma (2020, Sep 5). KGMU Eye lecture: Newer Procedures in Strabismus Surgery. YouTube [Video]. Accessed via https://youtu.be/x25Pf1LQIi4] Figure 9: Modified Harada-Ito procedure, tenting of anterior SO fibres close to LR [From Strabismus Simplified (2nd ed., p. 230) by Sharma P, 2019. CBS Publishers & Distributors.] of ciliary circulation and may even be performed in topical anesthesia. Botulinum toxin injection has been used in cases of paralytic strabismus in combination with recession as a replacement for traction sutures. This helps to overcome the severe contracture of the unopposed antagonist muscle in cases of chronic paralytic strabismus. It avoids the problems of traction sutures including infections, corneal exposure, and scleral erosion. In restrictive strabismus, cryopreserved amniotic membrane has been used to cover defects or to reduce muscle fibrosis and adhesion12 For very large angle strabismus, several techniques have been tried in combination with resectionrecession procedures. These include muscle recession combined with central tenotomy 13 or botulinum toxin augmentation14, medial rectus elongation 15 and Z tenotomy. A muscle transplantation combined with resection-recession procedure for large angle esotropia has also been attempted.11 Here, when doing a resection, a portion of the resected muscle (about 3-6 mm) is kept aside and later sutured to the muscle being recessed. This procedure helps to avoid surgery in the dominant eye. Moreover, the transplanted muscle is acts as a spacer without significantly affecting motility. Lastly, anterior superior oblique tuck has been described for small excyclotorsions. This procedure is similar to the Harada-Ito technique except that anterior fibres of the SO are simply tucked using non-absorbable suture. To conclude, several innovations in surgical techniques have been described over the last few years. These aim to make strabismus surgery minimally invasive, preserve anterior segment circulation, improve comfort by introducing topical anesthesia, reduce periocular scarring and so on. Although the studies describing these techniques are small and with short follow ups, they can be easily learnt by the skilled surgeon 76 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

Figure 11: Mini-tenotomy procedure. From “Mini-tenotomy procedure to correct diplopia associated with small-angle strabismus” by Wright KW. Trans Am Ophthalmol Soc 2009;107:97-103 Conflicts of interest There are no conflicts of interest. References 1. Mojon DS. Review: minimally invasive strabismus surgery. Eye (Lond) Nov 28, 2014 2. Bhaskaran, K., Shashni, A.K., Sharma, P., Saxena, R., Phuljhele, S. Combined resection-recession in true divergence excess sensory exotropia. Journal of AAPOS, 2019: 23 (5), pp. 258.e1-258.e4. 3. Elliot RL and Nankin SJ. Anterior transposition of the inferior oblique. J Paediatr Ophthalmol Strabismus 18:35, 1991. 4. Prieto-Diaz J. Management of superior oblique overaction in A-pattern deviations. Graefe’s Arch Clin Exp Ophthalmol 226: 126, 1988 5. Sen, S., Dhiman, R., Saxena, R., Phuljhele, S., Sharma, P. Vertical rectus transposition procedures for lateral rectus palsy: A systematic review. Indian Journal of Ophthalmology, 2019:67 (11), pp. 1793-1799. 6. Sharma, P., Saxena, R., Bhaskaran, K., Dhiman, R., Sethi, A., Obedulla, H. Augmented medial transposition of split lateral rectus in the management of synergistic divergence Journal of AAPOS, (2020) 24 (1), pp. 37-40. 7. Saxena R, Sethi A, Dhiman R, Sharma M, Sharma P. Enhanced adjustable nasal transposition of split lateral rectus muscle for surgical management of oculomotor nerve palsy. J AAPOS. 2020 Jun;24(3):183- 186. doi: 10.1016/j.jaapos.2020.02.013. 8. Sharma P, Chaurasia S, Rasal A, Angmo D. Synergistic innervational downshoot: a distinct vertical dysinnervation pattern and its unique management. Can J Ophthalmol. 2017 Feb;52(1):e31-e38. 9. Wright KW. Mini-tenotomy procedure to correct diplopia associated with small-angle strabismus. Trans Am Ophthalmol Soc 2009;107:97-103 10. Leenheer RS, Wright KW. Mini-plication to treat small-angle strabismus: A minimally invasive procedure. J AAPOS 2012;16:327-330 11. Pineles SL, Chang MY, Holmes JM, Kekunnaya R, Ozkan BS, Velez FG. Innovative techniques for the treatment of adult strabismus. J AAPOS 2019;1-8. https://doi.org/10.1016/j.jaapos.2018.10.018. 12. Strube YN, Conte F, Faria C, Yiu S,Wright KW. Amniotic membrane transplantation for restrictive strabismus. Ophthalmology 2011; 118:1175-9. 13. Ameri A, Akbari MR, Keshtkar Jaafari AR, Rajabi MT, Fard MA, Mirmohammadsadeghi A. Combining rectus muscle recessions with a central tenectomy to treat large-angle horizontal strabismus. J AAPOS 2014;18:534-8. 14. Lueder GT, Galli M, Tychsen L, Yildirim C, Pegado V. Long-term results of botulinum toxin-augmented medial rectus recessions for large-angle infantile esotropia. Am J Ophthalmol 2012;153:560-63. 15. Ameri A, Akbari MR, Keshtkar Jaafari AR, et al. Medial rectus muscle elongation, a technique to treat very large-angle esotropia. Graefes Arch Clin Exp Ophthalmol 2015;253:1005-11. and should be encouraged and gradually incorporated into routine practice. Financial support and sponsorship Nil. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 77

Abstract Theme Section Introduction Trabeculectomy remains the commonest glaucoma surgery performed since its initial description by Sugar and modifications by Cairns in 1968. Each modification aims to promote survival or safety of the procedure. Surgical modifications and innovations are borne out of need to increase efficiency and safety of accepted surgical procedure. This article describes three innovations in trabeculectomy. First is modified conjunctival incision with intent to reduce suturing induced discomfort and astigmatism. The second is to use a safer, physiological anti-fibrotic regimen as an alternative and / or addition to Mitomycin C for healthier blebs. Third is modified scleral incision for Manual small incision combined cataract trabeculectomy. a. Conjunctival frill incision Conjunctival incision during trabeculectomy has been conventionally described as either as “limbus-based conjunctival flap” given posterior to limbus or “fornixbased conjunctival flap” where conjunctiva is incised at limbus. Limbus-based conjunctival flaps leave conjunctiva undisturbed at site of scleral flap opening and minimize post op aqueous leak. It requires increased dissection and cutting of subconjunctival tissue with increased risk of conjunctival button-holing, and subsequent subconjunctival fibrosis. Dense fibrosis at site of incision can cause Ring of steel creation which limits posterior migration of bleb. Fornix-based trabeculectomy provides enhanced exposure to the limbal area allowing rapid superficial scleral flap dissection. It minimizes buttonholing, permits conjunctival reattachment to prior attachment site and reduces overhanging bleb. The The holy grail of a long surviving and safe trabeculectomy is still awaited. Modifications in the conventional trabeculectomy are required to increase the efficacy of the procedure, reduce the complications and minimize the bleb induced discomfort. Three of the innovations successfully used for over a decade are described in this paper, namely modified conjunctival incision, novel manual SICS trabeculectomy scleral incision and use of amniotic membrane as an anti-fibrotic adjunct in trabeculectomy. Keywords: Conjunctival Frill Incision, Trabeculectomy Induced Astigmatism, Amniotic Membrane In Trabeculectomy, Combined Sics Trabeculectomy, Wy Incision, And Scleral Incision Address for correspondence: Kirti Singh, MD, DNB, FRCS, FAIMER, DHA Editor, Delhi Journal of Ophthalmology Dir Prof and Director GNEC, State Nodal Officer NPCB, Guru Nanak Eye Center, Maulana Azad Medical College and Associated Hospital’s Ranjit Singh Marg, New Delhi, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Singh K. Innovations to make glaucoma surgery safer. Delhi J Ophthalmol 2022;32:78-81. Innovations to Make Glaucoma Surgery Safer Kirti Singh Department of Ophthalmology, Guru Nanak Eye Centre, Maulana Azad Medical College and Associated Hospitals, New Delhi, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_85_23 Submitted: 01‑Feb‑2023 Accepted: 13‑Feb‑2023 Published: 31-May-2023 Figure 1: (a) Diagrammatic depiction of Conjunctival frill incision (b) Conjunctival incision at start of closure 78 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

incision has the potential of causing leaks unless methodical closure with bleb forming sutures anchored to limbus is done, which contributes to suture induced astigmatism. Modifications in technique have been elaborated to reduce bleb leak.1, 2 Conjunctival frill conjunctival incision was a novel innovation, devised to reduce patient discomfort, surgical induced astigmatism induced by conventional fornix or limbus based. This incision reduces distortion at the surgical limbus. Its suturing involves use of lesser number of sutures than the conventional fornix based incision thereby significantly reducing WTR surgically induced astigmatism, noted in fornix based flaps.3, 4 Surgical technique The conjunctival incision is made 1-1.5 mm from limbus leaving a frill of conjunctiva attached at limbus. Incision is sutured with a round body 8-0 monofilament nylon, in a running, horizontal mattress type, with both ends being knotted away from the superior limbus. (Figure 1). The conjunctival suture is removed on slit lamp within 3-4 weeks as it becomes loose. The advantages of this incision is less suture induced discomfort, suture induced astigmatism (SIA) and tear film disruption. In addition expected scarring at incision site occurs 2mm from limbus, preventing an overhanging bleb. The comfort to patient is much more than Figure 2: (a-c)Trabeculectomy bleb with conjunctival frill incision at 2 weeks( sutures in situ) and 4 weeks ( after suture removal) Figure 3: (a-c )Phacotrabeculectomy with conjunctival frill incision at 2 weeks and 8 weeks (after suture removal). Bleb with conventional fornix based flap Figure 4: (a) Amniotic membrane being placed in sub-conjunctival place prior to conjunctival suturing (b) Amniotic membrane bleb Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 79

the fornix based flap.5,6 The technique has been used by us for trabeculectomy and combined surgery (Figure 2, 3). b. Use of amniotic membrane as an antifibrotic adjunct Human amniotic membrane is known for its antifibrotic, antiinflammatory and anti-angiogenic properties, down regulation of TGF-β2, low healing response, poor immunogenicity, ability to keep potentially adhesive surfaces apart and reduced fibroblast growth has favored its use as a potential modulator in trabeculectomy.7 It is a physiological and safer anti-fibrotic compared to Mitomycin C.8 Procedure: Commercially available sero-negative amnion is cut into pieces. A piece of membrane large enough to cover the scleral flap and overlap it by 4-5 mm, is placed on the sclera after placing the scleral sutures (fixed and releasables), with the epithelial side (non-sticky) up. The edges are then tucked in beneath the conjunctival flap. Conjunctival incision is then sutured taking care not to include the amniotic tissue in the bites. Bleb titration through side port is done at the end. Bleb morphology with use of amnion exhibits reduced vascularity compared to Mitomycin C, and the blebs very rarely if ever become avascular. The amnion integrates into tissues over a period of few weeks leaving no residue. (Figure 4). c. SICS Trabeculectomy Combined cataract and trabeculectomy is often required in situations of significant cataract and uncontrolled glaucoma. This is more often required in angle closure glaucoma Figure 5: (a-d) Diagrammatic depiction of W V incision. (a)Amniotic membrane being placed in sub-conjunctival place prior to conjunctival suturing (b) Amniotic membrane bleb Figure 6: (a-f) Combined surgery (a) Marking W incision in sclera (b) Apex of V is then raised and corneal entry is made with angled keratome, which is extended laterally to encompass the entire inner dissection into clear cornea (c) After nucleus delivery and cortex aspiration IOL insertion is being done. (d) Inner sclerostomy using a Kelly’s punch and peripheral iridectomy (e) Scleral sutures are being inserted (f) Amniotic membrane is being layered over the sclera 80 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

situations with high lens vault. For elderly patients with limited resources and/or availability to health care combined surgeries offers control of both pathologies at one instance, reduces use of anti-glaucoma medications and improves patient quality of life. Refinement in manual small incision cataract surgery with trabeculectomy using W-Y shaped incision is a technically easy surgery with use of 2 – 3 sutures. Procedure: After conjunctival flap creation and cautery, a superficial scleral flap is fashioned using a WV incision. Gentle dissection in dotted plane is done till 1 mm inside clear cornea (like for manual small incision cataract surgery) (Figure 5a). From a side port capsulorrhexis is done under viscoelastic cover. The apex of V is then raised and corneal entry is made with angled keratome. (Figure 5 b and c) This is then extended to edges of dotted line, like for a manual SICS incision. Raising the flap converts the incision into a V shaped one, thereby the name. Subsequent step are of hydrodissection, rotation of nucleus followed by nucleus delivery, cortical aspiration and IOL insertion. The pupil is then miosed with use of intracameral pilocarpine. This is followed by creation of inner sclerostomy using a Kelly punch and peripheral iridectomy (Figure 5 d). Scleral sutures are placed at apex of V (fixed 10 zero monofilament nylon). Two releasable sutures are inserted at base of V. Scleral flap titration is done from side port and conjunctival flap closure is done with or without use of amniotic membrane. Suture removal has similar time line to trabeculectomy, however bleb height is lesser with combined surgery. Figure 6a. Marking W incision in sclera Figure 6b. Apex of V is then raised and corneal entry is made with angled keratome, which is extended laterally to encompass the entire inner dissection into clear cornea Figure 6c. After nucleus delivery and cortex aspiration IOL insertion is being done Figure 6d. Inner sclerostomy using a Kelly punch and peripheral iridectomy Figure 6e. Scleral sutures are being inserted Figure 6f. Amniotic membrane is being layered over the scleral flap (Figure 7) depicts the magnified view of releasable sutures being placed . (Figure 7 a). A fixed suture is there at apex of scleral flap. A releasable suture is being tied at the arm b. 3 sutures are in position , fixed at apex and 2 releasables at the base of two side arms of triangular flap (the V) Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Wise JB. Mitomycin-compatible suture technique for fornix based conjunctival flaps in glaucoma filtration surgery. Arch Ophthalmol 1993; 111:992–7. 2. Kirk TQ, Condon GP. Modified Wise closure of the conjunctival fornixbased trabeculectomy flap. J Cataract Refract Surg 2014; 40(3): 349–53. 3. Hugkulstone CE. Changes in keratometry following trabeculectomy. Br J Ophthalmol 1991; 17: 217-18. 4. Kook MS, Kim HB, Lee SU. Short term effect of Mitomycin-C augmented trabeculectomy on axial length and corneal astigmatism. J Cataract Refract Surg. 2001; 27: 518–23. 5. Singh K, Bhattacharyya M, Wali K, Sumit Kumar S. Smile Incision: An Innovation in Glaucoma Surgery. Delhi J Ophthalmol 2016, 26 , 261-3 6. Singh K, Bhattacharyya M, Kumar S. Merits of conjunctival frill incision in reducing trabeculectomy-induced astigmatism and patient discomfort. Indian J Ophthalmol. 2021 Apr;69(4):882-885 7. Garg A, Singh K, Mutreja A, Wali K, Bhattacharjee M. Amniotic membrane in ophthalmology: A versatile wonder. MAMC J Med Sci 2015; 1:126-30. 8. Yadava U, Jaisingh K, Dangda S, Thacker P, Singh K, Goel Y. Simultaneous use of amniotic membrane and Mitomycin C in trabeculectomy for primary glaucoma. Indian J of Ophthalmol 2017 Nov 65(11):p 1151-1155 Figure 7: Dpicts the magnified view of releasable sutures being placed . (a) A fixed suture is there at apex of scleral flap. A releasable suture is being tied at the arm (b) 3 sutures are in position , fixed at apex and 2 releasables at the base of two side arms of triangular flap (the V) Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 81

Abstract Theme Section Overview Glaucoma is the second leading cause of irreversible blindness worldwide; early diagnosis and prompt management form the pillars that combat this permanently blinding disease. Intraocular pressure (IOP) is the only modifiable risk factor and currently all therapeutic approaches are directed towards its control. The goal of treatment is to conserve the quality of life (QoL) and preserve the visual function of patients by lowering IOP. Among the possible therapeutic options that ophthalmologists can choose are medical therapy with topical anti glaucoma medications (AGM), laser, or surgical therapy. The historical mainstay of glaucoma treatment is AGM, but this may have significant issues related to compliance and adherence, ocular surface disease (OSD), intolerance as well as cost implications. Laser (iridotomy in angle closure and trabeculoplasty in open angle), and traditional incisional blebforming glaucoma surgery (trabeculectomy and glaucoma drainage device, GDD) are the other two modalities that may be used. These latter bleb forming procedures, albeit effective, are invasive ones with a unique set of vision threatening complications. Trabeculectomy (trab) has been the mainstay surgical approach in primary glaucomas. However, achieving the desired balance between long‑term success of filtering blebs versus early failure due to scarring of blebs and hypotony due to dysfunctional filtering blebs pose a unique challenge. Thus, the setting is just right for alternative surgical modalities with a better safety profile, to be less invasive but effective too. This requirement paved the path for change, which initially was in the form of non-penetrating glaucoma surgery (NPGS – viscocanalostomy, deep sclerectomy) and even the use of a cylindrical device (Express device, ED) under a trabeculectomy flap. NPGS did not find global acceptability, perhaps because of its initial steep learning curve. However, all these procedures, like its predecessors were sub-conjunctival in nature, with very similar concerns. The ED and its cylindrical form proved to be a game-changer for the development of newer devices that explored the natural drainage pathways of the eye viz. the trabecular meshwork and the supra-choroidal space. Therefore, at the turn of the century, microinvasive glaucoma surgeries (MIGS) came into being. This terminology was coined by Iqbal Ike Ahmed, MD (University of Toronto, Canada) in 2009, setting a distinct demarcation between it and bleb-forming traditional surgeries (trab and GDD). Several modalities may be used in the treatment of glaucoma - including medical, laser and surgical. Surgical treatment has so far been subconjunctival in nature and bleb-dependent, with inherent limitations despite being efficacious. This article focuses on the newer glaucoma procedures, viz-a-viz microinvasive glaucoma surgeries (MIGS) that have recently been deployed with favourable results. MIGS works via various mechanisms, by-passing trabecular meshwork by implanting a stent or excising the trabecular tissue, enhancing aqueous outflow through Schlemm’s canal or, shunting the aqueous to the suprachoroidal space. As such it has become mostly ab-interno which has enhanced its safety profile making it suitable for use in mild-to-moderate glaucomas i.e. much earlier on in the disease spectrum. The majority of the ab-interno procedures and devices require a mastery of intra-operative gonioscopy. Keywords: Minimally Invasive Glaucoma Surgery MIGS Anti-glaucoma medications iStent iStent Inject Hydrus GATT Endocyclophotocoagulation Address for correspondence: Vanita Pathak Ray, Director Glaucoma and Senior Glaucoma and Cataract Specialist Department of Glaucoma, Centre for Sight, Banjara Hills, Hyderabad, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Ray VP, Ramzan R. Innovations in glaucoma surgeries. Delhi J Ophthalmol 2022;32:82-7. Innovations in Glaucoma Surgeries Vanita Pathak Ray, Rahila Ramzan Department of Glaucoma, Centre for Sight, Banjara Hills, Hyderabad, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_86_23 Submitted: 16‑Dec‑2022 Accepted: 20‑Jan‑2023 Published: 31-May-2023 82 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

Table 1: Classification of MIGS according to function I. Increasing Trabecular outflow – target Schlemm’s canal II. Suprachoroidal shunts – uveo scleral outflow III. Subconjunctival filtration (MIGS PLUS) IV. Reduction of aqueous production iStent®, iStent®inject iStent Supra XEN Endocyclophotocoagulation Hydrus MINIject PreserFlo Gonioscopy assisted Transluminal Trabeculotomy (GATT) e.g. OMNI, iTrackTM Suture GATT* Cypass (withdrawn) Trabectome Kahook Dual Blade (KDB) Trabeculotomy Bent Needle A-Interno Goniectomy (BANG)* *Cost-effective alternatives in italics *Table adapted from Clinical Handbook of Glaucoma, Incessant Nature Science Publishers, 2023'2 Table 2: summarizes a few of the studies related to MIGS procedures and devices mentioned above. MIGS Procedure *With cataract extraction Author /year/ journal Study Type Duration Decrease in IOP Decrease in Medi-cations [7] iStent® Micro-Bypass G1* Craven RE/ 2012/ JCRS Random¬ized controlled trial 2 years 8.4 mmHg 0.8 [7] iStent® Micro-Bypass G1* Craven RE/ 2012/ JCRS Random¬ized controlled trial 2 years 8.4 mmHg 0.8 [8] iStent® Inject G2 Fea AM/2014/ Clin Ophthalmol Pro¬spective, random¬ized trial 1 year 8.1 mmHg Not available [9] iStent® devices G1 & G2 (standalone) Healey PR/2021/J Glaucoma Meta-analysis 5 years 6.6 mmHg 1.2 [10] Hydrus Microstent Horizon Study in controlled glaucoma* Ahmed IIK/ 2022/ Ophthalmology Randomi¬zed controlled trial 5 years 1.1 mmHg 1.2 [11] Hydrus Microstent* Pfeiffer N/ 2015/ Ophthalmology Randomi¬zed controlled trial 2 years 9.4 mmHg 1.5 [12] Ab interno canalo¬plasty Ellex iScience Case-series review 1 year 4.0 mmHg 1.0 [13] Gonioscopy-assisted trans¬luminal trabecul¬otomy (GATT) Grover DS/ 2014/ Ophthalmology Retro¬spective review 1 year 8.4 mmHg 1.9 [14] Gonioscopy-assisted trans¬luminal trabecul¬otomy (GATT) Guo GY/ 2020/ tnt J Ophthalmol Meta-analysis 3 years 9.81 1.68 [15] Trabectome* Kaplowitz K/ 2016/ BJO Meta-anal¬ysis 2 years 7.9 mmHg 0.9 [16] Kahook Dual Blade trabeculotomy* Dorairaj SK/ 2018/ Advanced Therapeutics Prospective 1 year 4.4 mmHg 0.8 [18,19] iStent® Supra Myers JS/ 2014 Emerick GT/ 2014 Pro¬spective, single arm clinical trial 2 years 7.8 mmHg Not available [20] CyPass Micro-Stent* Vold S / 2016/ Ophthalmology Random¬ized controlled trial 2 years 7.4 mmHg 1.2 [21] XEN Glaucoma Treatment System Allergan Inc. Pro¬spective, single arm clinical trial 1 year 9.2 mmHg 1.8 [22] PreserFlo (formerly InnFocus MicroShunt)* Batlle JF, 2016/ JoG Pro¬spective, single arm clinical trial 3 years 16.2 mmHg 1.6 [25] Endocyclophotocoagulation* Pathak Ray V/ 2019/ International Ophthalmology Retrospective study 1.3 years 15 mmHg in uncontrolled PACG 2.5 mmHg in controlled PACG 3 (in both controlled and uncontrolled PACG) [26]Endocyclophotocoagulation* Pathak Ray V/ 2020/ Ophthalmology Glaucoma Prospective randomised 1 year 9.6 mmHg 2.4 Reference number in parenthesis 'Table adapted from Clinical Handbook of Glaucoma, Incessant Nature Science Publishers, 2023'2 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 83

Minimally invasive glaucoma surgery (MIGS) is an emerging field in open angle glaucoma (OAG) management (and in angle closure if the angle opens post laser peripheral iridotomy, LPI) with a promise to offer a reduction in IOP and AGM burden without the comparatively high risk of complications associated with more invasive incisional procedures. The introduction of new devices and procedures that can lower IOP in a safer and less invasive fashion than traditional glaucoma surgery has made it possible to consider a more proactive approach to surgical glaucoma management, at a much earlier stage, rather than only when the disease is advanced. MIGS The Food and Drug Administration (FDA of USA) described MIGS as “a type of IOP lowering device used to lower IOP using an outflow mechanism with either an ab-interno or abexterno approach, associated with little or no scleral dissection and minimal or no conjunctival manipulation.[1] Microinvasive glaucoma surgeries tend to have following characteristics - 1. Minimally traumatic 2. Moderate efficacy 3. High safety 4. Can be easily combined with cataract surgery. 5. Rapid recovery and visual rehabilitation, with fewer postoperative visits and manipulations 6. Usually indicated in mild-to-moderate disease 7. Usually indicated in open angles These procedures aim at preserving the normal anatomy of the ocular surface; conjunctiva and sclera are either not disturbed or minimally handled (as in MIGS Plus procedures – e.g. PreserFlo formerly InnFocus). Major advantage of MIGS procedures and devices Table 1[2] is that they are bleb-independent; therefore risk of hypotony and choroidal effusions and other bleb-related complications viz. bleb leak, blebitis, bleb-associated endophthalmitis, bleb-dysaesthesia etc are all avoided, with the exception of sub-conjunctival filtering MIGS-Plus devices. The operating time is much shorter and they can be easily combined with phaco surgery. The procedures and devices are very patientcentric – lesser number of post-operative visits, rapid recovery and early visual rehabilitation and reduction in AGM – all lead to improvement in the QoL. Furthermore, they can be offered earlier on in the disease, rather than the need to wait for the disease to progress or become uncontrollable and /or advanced. Being atraumatic to the conjunctiva and sclera, trabeculectomy can still be performed, should it be required in the future.2-5 The main disadvantage of these MIGS procedures is its modest ability to reduce IOP. It is therefore generally not recommended in advanced disease, nor in situations where IOP is uncontrolled despite maximally tolerated medications. Furthermore, they require the additional skill of intra-operative gonioscopy. Cost of these devices can also be a barrier for its uptake. Different Types of Migs Approaches MIGS aimed at improving outflow through Schlemm’s canal by stenting it 1.iStent and iStent inject The iStent (Glaukos Corporation, CA, USA) or generation 1 (G1) device was approved by the FDA in 2012 and was the first ab interno glaucoma implant to be approved in the USA. The iStent inject (Glaukos Corporation) second generation device (G2) was approved by the FDA in June 2018.6 Both are made of heparin coated titanium, and whilst the iStent is 1 mm × 0.3 mm in size, the iStent inject is significantly smaller at only 360 μm × 230 μm in size. Only these two types are currently available in India (Figure 1 A intraoperative positioning of iStent G1 and 1 B – intraoperative positioning of iStent Inject, G2), though there are several other variants – iStent W with a broader base (360 μm × 360 μm) and iStent Infinite (3 injectable devices in one). All these devices are inserted in the trabecular meshwork visualized via intra-operative gonioscopy, using a disposable injector device through a clear corneal incision as a single procedure or in combination with cataract extraction, and in the case of iStent inject two devices come pre-loaded in the injector and can be placed 30˚-60˚ apart. Generally, iStent or iStent inject is indicated in mild to moderate glaucoma with the aim to reduce dependence on topical medications and/or to reduce IOP. These trabecular micro-bypass (TMB) devices have an advantage in that they are very small devices, and in fact, they are the smallest devices known to mankind, and so are unlikely to cause endothelial damage in patients with shallow Figure 1: (a)Intraoperative positioning of iStent G1 (inset) eye (b) Intraoperative positioning of iStent Inject, G2 (inset) b a 84 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

anterior chambers. There are multiple randomised control trials (RCT) in G1 and G2 versus phaco alone,7,8 but in a systematic review and metanalysis, Healey et al.9 reported that even a standalone iStent reduced IOP by 32.9% at 5 years along with reduction of AGM by 1.2 and only 2.6% eyes needed filtration surgery in the follow-up period. 2.Hydrus The Hydrus microstent (Alcon, USA) is an 8-mm intracanalicular scaffold that dilates an entire 90˚ quadrant of Schlemm’s canal to increase aqueous humor flow through the trabecular meshwork. Hydrus implant is introduced in a fashion like other TMB stents utilizing intra-operative gonioscopy. It is currently not available in India but the Horizon study at 5 years in 202210 has reported an increased rate of AGM-free eyes with a greater number of patients achieving IOP<18 mmHg when compared to phaco-alone. Pfeiffer et al in an RCT prior to that achieved >9 mmHg IOP lowering and a decrease in AGM by 1.5.11 MIGS aimed at improving outflow through ab-interno canaloplasty Gonioscopy assisted transluminal trabeculotomy (GATT): Ab-interno canaloplasty ABiC, utilizing intra-operative gonioscopy, (e.g OMNI device) is a procedure where a microcatheter is used to perform 360˚ viscodilation of Schlemm’s canal,12 without the requirement for suture (vs Viscocanalostomy). This reduces IOP by dilating the canal of Schlemm and downstream collector channels to improve aqueous outflow. A circumferential trabeculotomy can also be performed, called GATT. The indication for this in mild to moderate glaucoma, either as a solo procedure or in combination with other forms of trabecular micro-bypass devices to facilitate further dilation of the collecting channels, and greater outflow than would be achieved with these devices alone. Grover et al13 in a retrospective analysis, were the first to report a reduction in IOP by 8.9 mmHg and AGM by 1.9. Suture GATT is a cost-effective alternative, by running a 5/0 prolene suture the entire length of Schlemm’s canal utilizing intra-operative gonioscopy, retrieving and pulling the distal tip while applying traction to the proximal end of the suture. In 2020 a meta-analysis by Guo et al14 demonstrated a weighted mean reduction in IOP 9.81mmHg, but is was less so for suture GATT (7.57 mmHg vs 11.33 with ab interno catheter). MIGS aimed at improving outflow via unroofing of schlemm’s canal Ab-interno goniectomy 1. Trabectome: Trabectome or ab-interno trabeculotomy achieves an increase in aqueous humor outflow through the trabecular meshwork by applying a 0.8 W electrical current to ablate the trabecular meshwork. Access to the anterior chamber is achieved through a clear corneal incision and gonioscopy is used intraoperatively to visualize the trabecular meshwork. Trabectome and ABiC are significantly differentiated from the other trabecular microbypass techniques, as no indwelling devices are left in the eye after the operation. A meta-analysis in 201615 found significant weighted mean reduction in IOP and AGM in phaco-Trabectome eyes compared to reduction in Trabectome alone eyes. 2.Excisional goniotomy with Kahook Dual Blade (KDB): Excisional goniotomy or trabeculotomy facilitates increased aqueous outflow by a device such as the KDB (New World Medical, Rancho Cucamonga, CA) by incising the trabecular meshwork utilizing intra-operative gonioscopy. In theory it avoids the thermal damage associated with Trabectome and does not leave remnant trabecular meshwork leaflets in-situ (with risk of fusion) such as that with GATT. Dorairaj et al16 prospectively studied the effect of KDB with phaco and found a modest response. On the other hand, a prospective RCT17 comparing phaco-KDB with phaco alone found no difference between groups. Although KDB is now available in India, Bent Needle AbInterno Goniectomy (BANG) has gained popularity as it is a cost-effective version of KDB (and Trabectome) and can achieve the same effect at a fraction of the cost. It un-roofs the Schlemm’s canal with a decisive excision of the trabecular meshwork utilizing intra-operative gonioscopy. (Figure 2) MIGS aimed at creating an outflow channel through the supraciliary space 1. MINIject: The MINIject device (iStar Medical, Belgium) is a 4 mm stent designed to follow the curvature of the sclera and utilizes porous silicone to allow aqueous outflow via the uveoscleral pathway. 2. iStent Supra: iStent Supra (Glaukos Inc, CA, USA)18,19 is currently an experimental micro-bypass stent which also harnesses the uveoscleral pathway. 3. CyPass: Withdrawn CyPass (Alcon, USA) was a very effective tubular stent20 which aimed to reduce IOP by shunting fluid through a passage into the supraciliary space, has been withdrawn due to concerns related to increased endothelial cell loss. MIGS-PLUS devices targeted at the subconjunctival space 1.Xen: The XEN gel implant (Allergan Inc, Irvine, CA, USA) is a form of MIGS targeting aqueous outflow to the subconjunctival space The XEN gel stent is implanted into the trabecular meshwork with a needle through an ab-interno approach, which is then advanced to puncture full-thickness sclera and pass the flexible stent into the sub-conjunctival space.21 This then creates a channel for aqueous humour outflow and creates a bleb to reduce IOP. This is currently not available in India. XEN EX is the nomenclature for XEN being implanted abexterno. XEN is indicated in more advanced glaucoma; as it is a bleb-based procedure it has the same risks/complications associated with it, with the rate of needling of bleb being approximately 50%. Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 85

Figure 2: Intra-operative view of unroofed Schlemm’s Canal (left - arrow) and trab meshwork excised (right – arrow) in Bent Needle Ab-iNterno Goniectomy (BANG) procedure Figure 3: Endpoint of endocyclophotocoagulation – whitening and shrinkage (left ciliary process) 2.PreserFlo microshunt The PreserFlo microshunt (Santen Inc, Emeryville, CA, USA) previously known as the InnFocus microshunt aims to address the need for a form of MIGS that can be effectively applied in moderate to severe glaucoma due to its ability to reduce IOP substantially.22 The PreserFlo device is implanted into the subconjunctival space below Tenon’s capsule via an ab-externo approach and threaded through a needle tunnel into the anterior chamber. The biocompatible material of the PreserFlo tube (SIBS) in combination with intraoperative Mitomycin C aids in the reduction of scarring and fibrosis; however, this too, is currently not available in India. MIGS targeting the ciliary process Endocyclophotocoagulation Endocyclophotocoagulation (ECP) was first described by Uram23 in the 1990’s and can be considered as the first MIGS and is available in India. It is ab-interno, minimally invasive and can be safely combined with cataract surgery;24 with the added advantage of not requiring intra-operative gonioscopy. In fact, it can also be done when cornea is unclear. It is efficacious and safe and is delivered independent of the angle status which makes it very versatile. It can, therefore, be used in primary and secondary open and angle closure glaucoma as well as in refractory glaucomas. It delivers 810nm diode laser to the ciliary processes (CP) to reduce the production of aqueous humor; whitening and shrinkage of the CP under direct visualisation is the endpoint of this targeted laser. (Figure 3) Probe is placed through clear corneal incision with an initial setting of 0.4-0.5 W; this is less than one-fourth the power used for trans-scleral delivery of the same. In the Indian population, it has been found to be particularly effective in Primary Angle Closure Glaucoma.25,26 Conclusion The advent of microinvasive glaucoma surgery has allowed for much improved and pro-active management of patients with mild to moderate glaucoma Table 2.2 MIGS can be easily incorporated into routine phacoemulsification surgery and can also be used in patients who are well-controlled on topical medications but desire drug independence. It is also an invaluable tool in case of intolerance to topical AGM as well as in ocular surface disease. Though it is currently mostly used in mild-to-moderate disease with open angle, it is possible that as surgeon experience matures and the number of MIGS approaches expands and are refined, these may even be utilized in more severe cases and across a wide range of clinical scenarios. These current innovations are but the beginning of the revolution that may yet see off the defacing bleb-forming surgeries. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Premarket Studies of Implantable Minimally Invasive Glaucoma Surgical (MIGS) Devices: Guidance for Food and Drug Administration 86 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

Staff, US Food and Drug Administration; 2015. Available from: https:// www.bit.ly/2L95zwp. 2. Pathak Ray V. Minimally Invasive Glaucoma Surgery. In Clinical Handbook of Glaucoma S Bhartiya, M Singh, and A Mitra (1st Edition). Incessant Nature Science Publishers, Noida, India 2023, pp. 306-319. 3. Saheb H, Ahmed, II. Micro-invasive glaucoma surgery: current perspectives and future directions. Curr Opin Ophthalmol. 2012;23(2):96-104. 4. Pathak Ray V. MIGS in India: is it time? Indian J Ophthalmol May 2022;70(5):1443-1445 5. Pathak Ray V. ‘Ushering in the era of MIGS in India?’ Kerala J Ophthalmol 2022;34:3-7 6. iStent inject Trabecular Micro-Bypass System (Model G2-MIS) – P170043. https://www.fda.gov/medical-devices/recentlyapproveddevices/ istent-inject-trabecular-micro-bypass-system-modelg2-mp170043.Published May 18, 2019. 7. Craven ER, Katz LJ, Wells JM, Giamporcaro JE, iStent Study G. Cataract surgery with trabecular micro-bypass stent implantation in patients with mild-to-moderate open-angle glaucoma and cataract: twoyear follow-up. J Cataract Refract Surg 2012;38(8):1339-1345. 8. Fea AM, Belda JI, Rekas M, Junemann A, Chang L, Pablo L, Voskanyan L, Katz LJ. Prospective unmasked randomized evaluation of the iStent inject® versus two ocular hypotensive agents in patients with primary open-angle glaucoma. Clin Ophthalmol 2014;8:875-882. 9. Healey PR, Clement CI, Kerr NM, Tilden D, Aghajanian L. Standalone iStent Trabecular Micro-bypass Glaucoma Surgery: A Systematic Review and Meta-Analysis. J Glaucoma. 2021 Jul 1;30(7):606-620 10. Ahmed IIK, De Francesco T, Rhee D, McCabe C, Flowers B, Gazzard G, Samuelson TW, Singh K; HORIZON Investigators. Long-term Outcomes from the HORIZON Randomized Trial for a Schlemm’s Canal Microstent in Combination Cataract and Glaucoma Surgery. Ophthalmology. 2022 Jul;129(7):742-751. 11. Pfeiffer N, Garcia-Feijoo J, Martinez-de-la-Casa JM, Larrosa JM, Fea A, Lemij H, Gandolfi S, Schwenn O, Lorenz K, Samuelson TW. A Randomized Trial of a Schlemm’s Canal Microstent with Phacoemulsification for Reducing Intraocular Pressure in Open-Angle Glaucoma. Ophthalmology 2015;122(7):1283-1293. 12. Ellex iScience. Ab-Interno Canaloplasty: A Comprehensive Minimally Invasive Glaucoma Surgery That Keeps Its Promise: 12 month case series review, 2016. http://www.ellex.com/wp-content/uploads/sites/9/ ABiC-Whitepaper-12-Months-1.pdf 13. Grover DS, Godfrey DG, Smith O, Feuer WJ, Montes de Oca I, Fellman RL. Gonioscopy-assisted transluminal trabeculotomy, ab interno trabeculotomy: technique report and preliminary results. Ophthalmology 2014;121(4):855-861. 14. Guo CY, Qi XH, Qi JM. Systematic review and Meta-analysis of treating open angle glaucoma with gonioscopy-assisted transluminal trabeculotomy. Int J Ophthalmol. 2020 Feb 18;13(2):317-324. 15. Kaplowitz K, Bussel II, Honkanen R, Schuman JS, Loewen NA. Review and meta-analysis of ab-interno trabeculectomy outcomes. Br J Ophthalmol. 2016 May;100(5):594-600. 16. Dorairaj SK, Seibold LK, Radcliffe NM, Aref AA, Jimenez-Román J, Lazcano-Gomez GS, Darlington JK, Mansouri K, Berdahl JP. 12-Month Outcomes of Goniotomy Performed Using the Kahook Dual Blade Combined with Cataract Surgery in Eyes with Medically Treated Glaucoma. Adv Ther. 2018 Sep;35(9):1460-1469. 17. Ventura-Abreu N, García-Feijoo J, Pazos M, Biarnés M, MoralesFernández L, Martínez-de-la-Casa JM. Twelve-month results of ab interno trabeculectomy with Kahook Dual Blade: an interventional, randomized, controlled clinical study. Graefes Arch Clin Exp Ophthalmol. 2021 Sep;259(9):2771-2781 18. Myers JS, Katz LJ. Results of suprachoroidal stent and topical travoprost for reduction of IOP and medication in open-angle glaucoma [Abstract]. Annual Meeting Program and Abstract Book. The 24th Annual AGS Meeting; February 27, 2014; Washington, DC., p. 70; 2014 19. Emerick GT. Highlights of the AGS Annual Meeting: The latest research findings from the 24th annual meeting of the American Glaucoma Society, held February 26th to March 2nd. Glaucoma Today 2014, http://glaucomatoday.com/pdfs/gt0314_rsrch.pdf. (March/April):10-11 20. Vold S, Ahmed, II, Craven ER, Mattox C, Stamper R, Packer M, Brown RH, Ianchulev T, CyPass Study G. Two-Year COMPASS Trial Results: Supraciliary Microstenting with Phacoemulsification in Patients with Open-Angle Glaucoma and Cataracts. Ophthalmology 2016;123(10):2103 2112. 21. Allergan Inc. Directions for use for the XEN Glaucoma Treatment System: Allergan, Inc., 2017. https://allergan-web-cdn-prod.azureedge. net/actavis/actavis/media/allergan-pdf-documents/labeling/xen/dfu_ xen_glaucoma_treatment_system_us_feb2017.pdf 22. Batlle JF, Fantes F, Riss I, Pinchuk L, Alburquerque R, Kato YP, Arrieta E, Peralta AC, Palmberg P, Parrish RK, 2nd, Weber BA, Parel JM. Three-Year Follow-up of a Novel Aqueous Humor MicroShunt. J Glaucoma 2016;25(2):e58-65. 23. Uram M. Ophthalmic laser microendoscope endophotocoagulation. Ophthalmology. 1992;99: 1829- 1832. 24. Uram M. Combined phacoemulsification, endoscopic ciliary process photocoagulation, and intraocular lens implantation in glaucoma management. Ophthalmic Surg. 1995 Jul-Aug;26(4):346-52. 25. Pathak Ray V. Intermediate results of phaco-endocycloplasty in an exclusive cohort of angle closure glaucoma: potential for change. Int Ophthalmol. 2019 Oct;39(10):2257-2265. 26. Pathak Ray V, Choudhari, N – ‘Phaco-Endocycloplasty versus PhacoTrabeculectomy in Primary Angle Closure Glaucoma: A prospective Randomised Study’ Ophthalmology Glaucoma Nov 2020; 3(6):434-442 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 87

Abstract Theme Section Introduction Vitreo-retinal surgery has evolved from the open sky vitrectomy as described by Kasne,1 to the modern standard MIVS by constant thrust of innovative ideas. The first closed vitrectomy system by Machemer utilised 17 G single port, which was later improved to standard three port 20 G system by O Malley and Heinz. Subsequently, introduction of 25G vitrectomy system in year 2002 led to improved wound integrity, globe stability and surgical manoeuvring. The current paradigm of vitrectomy set-ups includes smaller and stiffer instruments, with faster vitrectomy cut rates and better fluidics. Hypersonic vitrectomy2 is an exciting development which may further enhance the ease and safety of retinal surgery. In conjunction with improvement in instrumentation, the surgical viewing systems also saw advancement in terms of field of view, depth perception and contrast ensuring maximal surgical efficiency. The adoption of novel concepts of endoscopy and robotic surgery from other surgical disciplines into ophthalmology has upgraded the armamentarium of current surgeons. A brief overview of the new paradigms in vitreoretinal surgery is looked upon in this article. Hypersonic vitrectomy (HV) Ultrasonic energy, already in use in anterior segment for phacoemulsification, has now made its foray into posterior segment surgery. Although conventional fragmatome has been used for posterior lens extraction, but it is unsuitable for vitrectomy. The recently introduced hypersonic vitrector consists of a single lumen needle, with a closed tip and a port at the side.3 Unlike the pneumatic guillotine-based cutters which also contain an inner smaller needle that oscillates and cuts the vitreous, the HV needle achieves vitreous cutting (or liquefaction) by the high frequency vibration of the ultrasound tip. The liquefied vitreous in front of the tip is aspirated by a continuously open port, thereby eliminating the restrictions of duty cycle of conventional cutters. The traditional cutters require the vitreous to be drawn into the outer needle before it is cut, thereby limiting the proximity of cutter tip to retina. This also potentially can cause traction if the vitreous strand gets stuck between the two lumens. Theoretically these limitations are overcome by the HV, while providing better fluidics.4 In 2017, hypersonic vitrectomy received FDA clearance and was subsequently utilised in a series of patients.4 Initial experiences noted from surgeon’s responses included less traction, smooth Vitreo-retinal surgery has enabled the treatment of multiple posterior segment pathologies, which till few decades back were considered untreatable. With continuing innovation, modern retinal surgery is becoming more efficient and safer, while simultaneously making forays into newer paradigms. In this review article, we look at recent innovations that are changing the practice patterns among surgeons. Surgical innovations in instrumentation, visualisation and automation are discussed. The introduction of ultrasound energy in vitrectomy, termed as hypersonic vitrectomy, promises freedom from complications of current guillotine-based cutters. In terms of new avenues of visualisation , heads up 3-Dimensional (HUD) viewing systems, intraoperative OCT( i-OCT) and endoscopic vitrectomy permit better ergonomics, real time cross-sectional imaging and visualisation in opaque media respectively. Automation of surgical steps via robotic surgery heralds a new era in surgical safety. Keywords: Surgical Innovation, Hypersonic Vitrectomy, I-Oct, Endoscopic Vitrectomy, Robotics, 3-D Heads Up Display Address for correspondence: Raja Narayanan, MS, Department of Ophthalmology, Vitreo Retinal Diseases L. V. Prasad Eye Institute, Hyderabad, India. E-mail: [email protected] This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected] Cite This Article as: Sharma SV, Narayanan R. Surgical innovations in vitreo-retinal surgery. Delhi J Ophthalmol 2022;32:88-92. Surgical Innovations in Vitreo-Retinal Surgery Sumant Vinayak Sharma, Raja Narayanan Department of Ophthalmology, L. V. Prasad Eye Institute, Hyderabad, India Access this article online Quick Response Code: Website: https://journals.lww.com/djo DOI: 10.4103/dljo.dljo_71_23 Submitted: 12-Nov-2022 Accepted: 19-Jan-2023 Published: 31-May-2023 88 © 2023 Delhi Journal of Ophthalmology | Published by Wolters Kluwer - Medknow

experience and utility in mobile retina – although 35% found it dissatisfactory owing to difficulties like “inducing PVD with tough hyaloid” and “shaving in blood”. The first in-human study, as reported by Stanga et al,5 found 255 micron port size of HV to be most preferred by surgeons. Additionally, the injection of dyes through the vitrector itself reduced the need for changing instruments intra-operatively. Core vitrectomy was successfully performed in all cases (20 out of 20) using HV, however PVD induction was unsuccessful in 2 out of 15 cases. Recent multicentric study on HV by Romano et al2 found issues in the form of inadequate vitreous liquefaction, leading to decreased vitreous flow and consequent vitreous incarceration in the probe. This highlights the need for further refinement of instrumentation, as the purported benefit of these systems is in fact a reduction in these complications. The settings that were considered optimum were a stroke length of 60 microns, with a vacuum of 40 mm Hg, in both core and peripheral vitrectomy. Encouragingly, the primary anatomic success was seen in 98% of the patients. HV certainly represents the next step towards efficient vitreous removal; however, it needs further optimization before it can replace current vitrectomy systems. Heads-up 3- dimensional (HUD) viewing system First reported by Riemann6, and popularized by Claus Eckardt7 in vitreoretinal surgery, “heads up” display permits the surgeon to view the surgical field on a screen, as opposed to conventional viewing through microscopic eye-pieces. The use of polarized glasses to view the screen renders the horizontally mixed images as separate input in each eye, giving rise to 3-dimensional perception.8 This is a “passive” 3-D viewing system, which is commercially available in NGENUITY® 3D Visualization System and Artevo 800 (Zeiss, Germany). Head mounted systems8 on the other hand uses a display helmet, which is worn by the surgeon and eliminates the need for constant viewing at a screen. The benefits of 3-D viewing systems pertains to surgeon ergonomics, better visualization, patient related factors and educational purposes. Lesser incidence of musculo-skeletal pain9 and neck and back discomfort10 has been reported with heads-up viewing, thus ensuring efficiency and longevity of surgeons. Importantly, increased depth of field6 (with lowering aperture size in NGENUITY® 3D Visualization System ) compared to standard microscope and improved contrast by usage of digital enhancement11 helps in improved surgical visualization. In fact, multiple studies12–14 have shown preference for heads up display by surgeons based on ease and comfort. The added advantage of achieving superior visual quality with lesser endo-illumination levels (~ 20%-30%) compared to conventional system reduces the risk of retinal toxicity.15 Viewing on a 3-D screen also helps trainees to stereoscopically appreciate the micro-surgical maneuvers, providing an excellent educational opportunity. Clinical outcomes with 3-D heads-up display have been comparable with conventional viewing systems in both macular surgeries16,17 and standard retinal detachment surgery18,19. However, Talcott et al17 found a longer surgical time for completion of peeling in macular surgeries, attributable to learning curve on the viewing system. In our experience , interestingly, a much higher macular hole closure rate is seen among trainee surgeons operating on the 3-D heads up display.20 A caveat with HUD is that there is a latency time( ~80 ms) between surgical movements and display; but it appears to be clinically inconsequential.11 The advantage of superior visualization with HUD also translates to better management of complex retinal cases.21 Our current practice involves using HUD for all vitreo-retinal procedures due to aforementioned benefits. Intraoperative Optical Coherence Tomography(i-OCT) Optical Coherence Tomography (OCT) has become an integral part in clinical evaluation of retinal disorders. The extension of OCT into the operating theatre (i-OCT) has further enhanced the surgical management, particularly in macular surgeries. During the initial days, handheld OCT probes22 were utilized preoperatively and/or during the vitreoretinal surgery, which necessitated the surgeon to pause the surgery for obtaining scans. The process to acquire these scans had a learning curve, was prone to motion artefacts and was obviously not useful for observing steps in real time. Subsequently, microscope mounted probes eliminated the need of hand control and provided stability while acquiring scans. The horizontal and vertical movements were controlled using the microscope foot pedal, thus reducing acquisition time. However, the similar prerequisite of pausing the surgical step to acquire scans did make the process cumbersome. Current generation of microscope integrated i-OCT have addressed this limitation by overlaying of OCT scan on the surgical view, allowing real time surgical tissue manipulations to be observed. This has opened a new dimension of visualization, which has been applied in both anterior and posterior segment surgeries. The commercially available systems include the Haag-Streit iOCT-system (Haag-Streit, Koeniz, Switzerland), the Zeiss platform Rescan 700 (Zeiss, Oberkochen, Germany), and the Leica EnFocus system (Leica, Wetzlar, Germany).23 With introduction of 3-D HUD, i-OCT is digitally enabled, which provides greater surgical visualization when compared to standard i-OCT microscopes.24 The current commercial systems utilize primarily spectral domain–OCT; use of swept-source OCT25 in future may further enhance the image acquisition. I-OCT has been extensively used in posterior segment. The DISCOVER26 trial noted that out of 593 posterior segment surgeries, surgeons altered their decision–making based on i-OCT in 173 eyes(29.2%). In macular surgeries, i-OCT can help confirm completion of membrane peeling without use of dyes27, position of ILM flaps in macular hole28 and in harvesting of retinal grafts for refractory MH.29 Especially Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022 89

in myopic maculopathy, fovea sparing ILM peeling30 can be performed under i-OCT guidance. In retinal detachment,31 i-OCT can help visualise proliferative membranes and aid in their removal. Other applications include assessment of paediatric patients under anaesthesia, to guide subretinal injections,32 placement of retinal implants33 and in chorioretinal biopsies.34 A limitation is that the metallic instruments used in vitreoretinal procedures cause shadowing on i-OCT scans, which may be addressed by using OCT compatible instruments35 in future. The quality is currently inferior compared to scans used in our clinics. Inspite of this, i-OCT is becoming an essential tool intraoperatively. Endoscopic Vitrectomy The current high-definition visualisation during vitreo-retinal procedures is subject to clear ocular media. The subset of eyes where visualisation through the pupil is not feasible become candidates for endoscopic visualisation. Akin to widely used endoscopy in other surgical specialties, it involves the use of a fibreoptic microendoscope which contains an objective lens system and a co-axial illuminating source which is connected to the central console. The lens system within the endoscope relays the information to the central console, where the real time image is observed on a two dimensional monitor. Commercially available devices include E4 Endoscopy and Laser System (EndoOptiks, Inc., Little Silver, NJ, USA) and AS 611(FiberTech, Co, Tokyo, Japan). The standard 3 port vitrectomy set-up is used for endoscopic vitrectomy, where one port each is utilised for infusion, instrumentation(e.g cutter, scissors) and microendoscope. Adding chandelier light source may further enhance endoscopic visualisation due to increased illumination of retinal structures. Surgeon must look at the 2-D screen while operating unlike conventional microscope. The obvious loss of stereopsis and small field of view makes this a challenging skill set to acquire. Intraoperatively, positioning the endoscope closer to or further from the tissue alters the field of view and magnification; simultaneously the surgeon utilises non stereoscopic cues to assess the exact tissue distance. There is a higher propensity to lose orientation of the field of view due to inadvertent rotation of micro endoscope, especially in the periphery. All these limitations may lead to incidences of retinal touch and complications. On the plus side, presence of high-definition camera and the freedom to view tissue at various angles and distances enables the surgeon to appreciate hitherto unappreciable micro-structural details. The ability to position the endoscope in periphery to view anterior structures such as pars plana and ciliary body affords enormous advantage even in routine vitrectomies, where a surgeon may switch to endoscopic view to tackle these areas. The clinical utility of endoscopic vitrectomy has been explored in multitude of posterior segment disorders. In a large series of 127 patients with retinal detachment by Yokoyama et al,36 endoscopy was used after core vitrectomy to drain subretinal fluid, perform endophotocoagulation of breaks and inspection of peripheral retina for any additional breaks. The reported success rate was 98.4% in this series for uncomplicated retinal detachments. In complex retinal detachments, Rezende et al37 utilised endoscopic assisted PPV and found better reattachment rates compared to PPV alone. Kaga et al38 described the novel technique of removing adherent vitreous to breaks in retinal detachment with PVR-grade C under air using endoscopy, and inserting microendoscope under the retina to visualise subretinal bands and extract them. Lee et al39 utilised endoscopic assisted PPV to remove anterior proliferative membranes in cases with chronic hypotony post retinal detachment repair and found good results in few of the patients. In cases with endophthalmitis with opaque corneas where timing of intervention is paramount, Dave et al40 found favourable anatomical outcome in 24(72.72%) out of 33 patients where endoscopic vitrectomy was performed. Endoscopic visualisation can also help in scleral fixation of IOL,41 removal of intraocular foreign bodies42–44, trauma45 and has been described in implantation of retinal implants46 and evacuation of subretinal bleeds.47 Apart from surgical modality, endoscopy can also be used as a diagnostic instrument specially in cases where anterior segment intervention is dependent on posterior segment viability. Tyagi et al48 evaluated 64 eyes with corneal opacities via diagnostic endoscopy, in which 30 eyes with poor visual prognosis could be identified, thus preventing further intervention which would have had no visual benefit. Robotic Vitreo-retinal Surgery The vitreo-retinal surgery in its current form is limited by extent of human precision, dexterity and variability of performance. Routine high precision movements in the tune of 150-200 microns, which further narrows down in macular surgeries, are required in vitreo-retina surgeries. The presence of physiological tremors and absence of tactile feedback from retinal tissues curtails the extent of micromovements possible. The application of robotics can potentially circumvent these drawbacks. Robotic systems that are currently available represent a spectrum of evolving technology. Hand-held systems aim to negate the tremors and utilise motion-scaling to help the surgeon perform more precise movements (e.g. MICRON) during routine procedures. The Preceyes Surgical System(PSS) is a tele-manipulation device with a “master-slave” design, wherein the input is dictated by the surgeon using a controller and the output is via a robotic arm, which is compatible with 23G,25G and 27G instrumentation. The surgeon has the option to perform routine steps without the system, and switch to it while performing finer steps. Currently it can also be used from a remote location, thus providing tele-surgery. Maberley et al49 found more precise movements and lesser incidence 90 Delhi Journal of Ophthalmology ¦ Volume 32 ¦ Issue 6 ¦ October-December 2022

of retinal hemorrhages with PSS compared to manual ILM peeling; however the robot assisted peeling took longer. Faridpooya et al50 found similar results in ERM peeling with PSS. In subretinal injection, PSS improved bleb formation and reduced reflux rates, thus potentially being useful in subretinal gene therapy.51 Intraocular robotic interventional surgical system (IRISS)52 represents further advancement in robotics technology, where multi-step procedures can be performed independently by the robot. The integration with OCT is used to control the instrument tip position; this potentially represents the first step towards fully automated surgeries. Another category of robotic devices is represented by OctoMAg,53 which utilises extraocular magnetic field to guide intraocular micro-robots. At present, the economic constraints, robotics being a nascent technology and issues with workspace intrusion limit their incorporation into routine set-ups.54 It certainly holds promise as the future of retinal surgery. Conclusion Vitreo-retinal surgery has seen considerable innovations in the past decade. It is imperative for modern surgeon to be open to these changes and adopt them in their practice to improve patient care. Newer avenues of visualisation in the form of HUD and intraoperative OCT provides more intraoperative surgical information to enable finer surgery. Endoscopy can help us provide treatment to patients where conventional visualisation is not possible. Hypersonic vitrectomy may enable us to perform more efficient and safer vitrectomies. And lastly, we may be able to surpass human limits of surgical prowess by the stability and precision of robotics. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Blodi CF. David Kasner, MD, and the Road to Pars Plana Vitrectomy. Ophthalmol Eye Dis. 2016;8(Suppl 1):1-4. doi:10.4137/OED.S40424 2. Romano MR, Caretti L, Ferrara M, et al. TWENTY-THREE-GAUGE HYPERSONIC VITRECTOMY: Real-World Surgical Evidence. Retina Phila Pa. 2021;41(12):2523-2530. doi:10.1097/IAE.0000000000003215 3. Stanga PE, Pastor-Idoate S, Zambrano I, Carlin P, McLeod D. Performance analysis of a new hypersonic vitrector system. PloS One. 2017;12(6):e0178462. doi:10.1371/journal.pone.0178462 4. Stocchino A, Nepita I, Repetto R, et al. Fluid Dynamic Assessment of Hypersonic and Guillotine Vitrectomy Probes in Viscoelastic Vitreous Substitutes. Transl Vis Sci Technol. 2020;9(6):9. doi:10.1167/tvst.9.6.9 5. Stanga PE, Williams JI, Shaarawy SA, et al. FIRST-IN-HUMAN CLINICAL STUDY TO INVESTIGATE THE EFFECTIVENESS AND SAFETY OF PARS PLANA VITRECTOMY SURGERY USING A NEW HYPERSONIC TECHNOLOGY. Retina Phila Pa. 2020;40(1):16-23. doi:10.1097/IAE.0000000000002365 6. 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