Efficacy and Safety of Diode Laser Transscleral Cyclophotocoagulation in Patients with Glaucoma.

Purpose: To evaluate the efficacy and safety of transscleral diode cyclophotocoagulation (TSCPC) at 2 years of follow up.

Methods: This is a retrospective review of the records of all adult patients who underwent their first TSCPC treatment between 2014 and 2019 at Unidade Local de Saúde de São João, Porto, Portugal. Data regarding intraocular pressure (IOP), best corrected visual acuity, number of IOP-lowering medications, use of oral acetazolamide, retreatments and complications during a 2-year period following TSCPC were registered. The primary outcome was overall success at 2 years, defined as IOP≥ 6 and ≤21 mmHg, with at least 20% IOP reduction from baseline, with or without IOP-lowering medications (qualified and complete success, respectively), without the development of phthisis bulbi or loss of light perception due to glaucoma and no further glaucoma procedures except TSCPC retreatment.

Results: Ninety-six eyes from 96 patients were included, mean age was 63 (±14) years. Mean IOP at baseline was 39.1 (±13.3) mmHg. Mean IOP reduction at 2 years was 18.5 (42.9%) mmHg (±16.0, min -16.0, max 56.0) (p < 0.001) and a significant reduction in the number of IOP-lowering medications and use of oral acetazolamide was observed. IOP reduction at 2 years was positively correlated with baseline IOP (r=0.682; p < 0.001). Overall success (including complete and qualified) was achieved in 42 patients (43.8%), with 34 (35.4%) presenting qualified success. Neovascular glaucoma (NVG) was the predominant diagnosis (n = 30, 31.3%), with a higher mean baseline IOP of 46.3 mmHg (±11.8, min 21.0, max 70.0) and a larger mean IOP reduction at 2 years of 24.7 (51.0%) mmHg (±16.4, min -2.0, max 55.0). Thirteen patients (13.5%) developed persistent hypotony, eight of which converted to phthisis bulbi, of which half had NVG.

Conclusion: TSCPC can be an effective IOP-lowering procedure, demonstrating a stronger effect when the preoperative IOP is highest. However, there is a wide variability in the effect (specially in eyes with NVG) and some relevant complications, including 8.3% of patients developing phthisis bulbi after 2 years of follow up.