Minimally Invasive Glaucoma Surgery (MIGS) in the Indian Context: The Potential of Gonioscopy Assisted Transluminal Trabeculotomy (GATT) in a Resource-Limited Setting

INTRODUCTION Glaucoma is one of the leading causes of irreversible blindness worldwide. In India, the burden of glaucoma is significant due to the large population and a growing elderly demographic. Managing glaucoma involves controlling intraocular pressure (IOP) to prevent optic nerve damage. Traditionally, glaucoma surgery has been invasive, requiring long recovery times, significant postoperative care, and a high risk of complications. However, advancements in surgical techniques have led to the development of minimally invasive glaucoma surgery (MIGS), a promising approach that offers reduced complications, shorter recovery periods, and quicker visual rehabilitation.[1,2] The gonioscopy-assisted transluminal trabeculotomy (GATT) is a novel and economical MIGS technique gaining attention in resource-limited settings like India.[3] This study aims to explore the potential of MIGS, with a specific focus on GATT, in addressing glaucoma treatment needs in India’s unique healthcare context. UNDERSTANDING GLAUCOMA AND ITS MANAGEMENT CHALLENGES IN INDIA India, with its diverse population, faces unique challenges in glaucoma management. The prevalence of glaucoma is estimated to be around 12 million and is expected to double (24 million) in 2040, with approximately 3 million people being visually impaired due to the disease. The increase in prevalence is attributed to a variety of factors, including population aging, late diagnosis, and limited access to healthcare facilities, especially in rural areas. The primary goal in glaucoma treatment is to lower IOP, the main risk factor for optic nerve damage. Traditional management options include medical therapy (e.g., eye drops), laser therapy, and surgical interventions. While medical therapy is commonly used, it often leads to poor compliance, especially in rural areas where access to healthcare resources may be limited. Laser procedures, such as trabeculoplasty, can help in managing IOP but may not always provide lasting results. Surgical interventions, specifically trabeculectomy and tube shunt procedures, are considered effective but come with significant risks, including infection, extensive scarring, corneal decompensation, uncontrolled IOP, hypotony, and the need for extensive postoperative care. These invasive surgeries also require specialized equipment and trained personnel, making them less feasible in resource-limited settings. THE RISE OF MINIMALLY INVASIVE GLAUCOMA SURGERY MIGS procedures represent a paradigm shift in glaucoma surgery. These techniques are designed to be less invasive, conjunctival-sparing, with smaller incisions, faster recovery times, and fewer complications. MIGS procedures include devices like the iStent, Hydrus microstent, and the Xen gel stent, among others, which are used to enhance aqueous humor outflow or reduce its production in the eye, thus controlling IOP. Unlike traditional glaucoma surgeries, MIGS procedures typically do not involve large incisions or the creation of filtering blebs, which reduces the risk of complications such as blebitis, bleb-related endophthalmitis, hypotony, and failure. This makes MIGS particularly attractive in settings where healthcare infrastructure and patient follow-up may be limited. GONIOSCOPY-ASSISTED TRANSLUMINAL TRABECULOTOMY IN THE CONTEXT OF MIGS The GATT technique is an innovative, cost-effective, and minimally invasive procedure that builds on the principles of traditional trabeculotomy but incorporates elements of MIGS. GATT can be performed with an iTrack illuminated microcatheter or a simple 5-0 prolene suture. Suture GATT has emerged as a potential game-changer in the Indian context, where affordability and access to high-quality surgical care are major concerns. Unlike other MIGS procedures, suture GATT does not require sophisticated instruments or devices. The procedure involves creating a small, controlled goniotomy with a 26-gauge needle in the trabecular meshwork [Figure 1b], through which the mushroom tip 5-0 prolene suture [Figure 1a] is circumnavigated 360 degrees [Figure 1c] and externalized with a Grieshaber Maxgrip end-grasping forcep [Figure 1d] to facilitate the outflow of aqueous humor through the removed area of trabecular meshwork/inner wall of Schlemm’s canal (TM/IWSC) to directly access SC, collector channels, aqueous veins, and downstream episcleral veins within the perilimbal sclera, thus lowering IOP. However, compared to traditional trabeculectomy, GATT involves less tissue dissection and reduces the need for intensive postoperative care.Figure 1: (a) The procedure involves creating a small mushroom-tip 5-0 prolene suture with low-temperature cautery. (b) 2 to 3 clock h of goniotomy with 26G needle in the anterior-most part of the pigmented trabecular meshwork, (c) Prolene suture is circumnavigated 360 degrees into Schlemm’s canal under direct gonioscopy view. (d) Externalized the Prolene suture 360 degree with Grieshaber Maxgrip end-grasping forcepsPOTENTIAL BENEFITS OF GATT IN INDIA Cost-EffectivenessOne of the major advantages of MIGS techniques, including GATT, is their cost-effectiveness. In India, where a significant portion of the population does not have access to private healthcare or insurance, cost is a major factor influencing treatment decisions. Suture GATT is a more affordable option compared to tube shunt surgeries and other device-based MIGS. The reduced need for postoperative care and long hospital stays make it a feasible choice for low-resource settings.Reduced Risk of ComplicationsTraditional glaucoma surgeries like trabeculectomy are associated with risks such as shallow chamber, bleb-related complications, postoperative hypotony, and bleb-related infection. However, GATT minimizes these risks through its minimally invasive approach and controlled tissue handling. As a result, patients are less likely to experience severe complications that require further interventions or prolonged recovery periods.Faster Recovery and RehabilitationThe minimally invasive nature of GATT allows for quicker recovery times. In a country like India, where many patients may need to return to work or resume daily activities quickly, a procedure with a shorter recovery period is highly advantageous. This allows patients to resume their normal lives without significant disruption.Lower Requirement for Follow-Up CareGATT requires less intensive postoperative monitoring and intervention compared to traditional glaucoma surgeries. This is particularly relevant in India, where regular follow-up visits may be difficult due to transportation issues, economic constraints, or lack of awareness. By reducing the burden of follow-up visits, GATT enhances accessibility to care and improves patient adherence.[4–6] Using data from the literature and the costs of the devices, the following cost per mmHg IOP was obtained [Table 1].Table 1: The economy of various MIGS proceduresThis comparison of cost per mmHg IOP decrease has several significant limitations, such as the protocols and population chosen. It is very clear that based on this simple analysis of the IOP-lowering effect relative to device cost, suture GATT is dramatically more cost-effective at lowering IOP than other MIGS devices. OTHER EVIDENCES: IN TERMS OF QALY AND ICUR The term “quality-adjusted life year” (QALY) is important to properly address cost-effectiveness. This term takes into consideration both the length (mortality) and quality (morbidity) of an individual’s life. Within ophthalmology, quality of life is most correlated with visual acuity in the better-seeing eye. When glaucoma leads to bilateral blindness, defined as vision of 20/800 in many studies, it has been suggested that this diminishes the quality of life of that patient by approximately 50%. The ability of a glaucoma treatment to prevent bilateral blindness, therefore, has a measurable utility to the patient. By comparing the number of QALYs conferred by a treatment to the cost of the treatment, a value of cost per QALY can be calculated. This is an analysis of cost-utility. The incremental cost-utility ratio (lCUR) is the comparison of the cost-effectiveness of two different treatments, in terms of cost per QALY.[7,8] “GATT combined with cataract surgery is three times more effective and fifty times less expensive than iStent combined with cataract surgery.” IMPLEMENTATION CHALLENGES AND CONSIDERATIONS While the benefits of MIGS/GATT are clear, its implementation in India does come with some challenges: TRAINING AND EXPERTISE Despite its relative simplicity, MIGS/GATT still requires skilled surgeons who are trained in the glaucoma subspecialty and clinical indirect and direct gonioscopy. In India, there is a shortage of trained ophthalmologists; hence, ensuring widespread training and education for ophthalmic surgeons is essential. Collaborative programs between academic institutions and hospitals could be a potential solution to this challenge. It is advised to practice routine clinical gonioscopy in the OPD with a 2-mirror gonio lens for all glaucoma cases to visualize the angle anatomy and also to document the gonio diagram on the pre-op case sheet before attempting MIGS surgery. The next advised step in learning MIGS is to start using direct gonioscopy (a Swan-Jacob lens is advised since it can be autoclaved) at the end of routine phacoemulsification. The head position of the patient is adjusted 30 degrees away from the surgeon, and the microscope is tilted 30 to 35 degrees toward the surgeon to achieve an en face view of the angle structures. Once the surgeon is comfortable with intraoperative gonioscopy, a limited goniotomy procedure—such as Tanito microhook ab-interno trabeculotomy or a Bent Ab-interno needle goniectomy with the help of a 25G or 26G needle—will be an ideal procedure to start with. WHAT HAMPERS A SURGEON FROM PERFORMING GATT ROUTINELY: POSTOPERATIVE HYPHEMA Reflux hyphema is known to occur intraoperatively, in the early postoperative period, and even in the late postoperative period, especially in angle-based surgeries involving 360 degrees, like GATT. The incidence of hyphema following GATT procedures varies from 0.97% to 38%. Over time, we have adopted a four-step technique that involves tamponading with air, saline, and adrenaline, and filling the anterior chamber with 20%–30% viscoelastic (1.4% Na hyaluronate) at the end of surgery, along with a wait-and-watch approach. With the adoption of our four-step technique, we were able to substantially reduce the occurrence of postoperative hyphema from 21.22% to 5.22% following GATT and the need for an anterior chamber washout from 9.4% to 1.3%. This technique may be invaluable in light of the rising trend of MIGS, in which the risk of hyphema tends to be higher.[9–15] CONCLUSION MIGS, specifically the suture GATT technique, offers a promising solution to the challenges of glaucoma management in India. The cost-effectiveness, reduced risk of complications, and faster recovery times make GATT a viable option, particularly in resource-limited settings. However, successful implementation of GATT on a large scale will require overcoming challenges related to training, awareness, and financial accessibility. By addressing these issues, GATT could play a pivotal role in reducing the burden of glaucoma-related blindness in India—especially among underserved populations. Special remarks from the father of GATT: “Keep up the work in the canal, a fertile area that needs continued exploration” Dr Ronald L. Fellman M “Need to continue advancing the field of GATT, especially in India” Dr Davinder S. Grover MD