GATT appears safe and effective for lowering IOP following corneal transplant

Investigators evaluated 24-month efficacy and safety outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) to determine its viability in eyes with a history of prior corneal transplant.

Study design

This was a retrospective case series of 39 eyes of 32 patients with a history of prior corneal transplant, including penetrating and/or lamellar keratoplasty, undergoing GATT at a single US center between 2016 and 2019. The main outcome measure was reduction in IOP and medication use at 24 months following GATT.

Outcomes

At 24 months, mean IOP had significantly decreased from baseline, from 30.9 mm Hg to 13.9 mm Hg. The number of IOP-lowering medications significantly decreased as well, from 4.2 to 0.6 medications. Visual acuities were also stable, with no significant Snellen line changes at 24 months compared with baseline. Seven eyes required reoperation for uncontrolled glaucoma after GATT (median: 8.5 months). Long-term graft survival was observed in patients following GATT, with 2.6% of patients needing repeat corneal surgery at 24 months and 14.3% of patients needing repeat surgery at 36 months. At 1 month post-surgery, 77% of patients had no complications, 3% had persistent hyphema, and 10% had corneal edema. Corneal edema resolved in all patients between 3 and 9 months after surgery, except in 1 patient who had corneal edema prior to GATT.

Limitations

This retrospective analysis had potential selection bias, as the decision to perform GATT was made at the surgeon’s discretion. Furthermore, the number of cases was small and the cases were reported from a single practice (where the GATT procedure was first described); this may limit generalizability of outcomes, especially in areas where GATT is not frequently performed.

Clinical significance

Treating glaucoma in post-corneal transplant patients can be challenging. While traditional glaucoma surgeries such as trabeculectomy, glaucoma drainage device, or cyclodestructive procedures are considered standard of care for eyes following corneal transplant surgery, they are associated with varying rates of success and carry significant risk of complications, including shorter time to graft rejection, greater likelihood of multiple rejection episodes, and greater chance of graft failure. Also, fitting contact lenses to optimize vision is challenging with a bleb or a drainage implant and carries with it the increased risk of endophthalmitis. This case series provides evidence suggesting that GATT may be considered as a reasonable, safe, and effective alternative for surgically lowering IOP in patients with glaucoma following corneal transplantation.