Effectiveness and safety of long duration versus short duration diode laser transscleral cyclophotocoagulation

Abstract

Purpose: To compare the efficacy and safety of diode laser transscleral cyclophotocoagulation using either the long duration or short duration protocol. Methods: Retrospective series of 23 consecutive patients with glaucoma who underwent continuous-wave diode laser transscleral cyclophotocoagulation from August 2016 to July 2018 at a tertiary hospital in Hong Kong. Laser pulse duration for the long and short duration protocols was defined as 3.0–4.0 and 1.5–2.0 s, respectively. Results: There were 15 male and 8 female Chinese subjects (23 eyes), age 49–90 (71.3 ± 2.7), with 10 subjects that underwent long duration cyclophotocoagulation (power 1239.2 ± 78.3 mW, spots 13.9 ± 1.4) and 13 subjects that had short duration cyclophotocoagulation (mean power 1817.3 ± 85.7 mW, spots 14.4 ± 1.0). Six months after long and short duration cyclophotocoagulation, intraocular pressure decreased significantly from 29.9 ± 7.8 to 21.1 ± 6.5 (p < 0.01), and from 35.4 ± 2.7 to 24.1 ± 3.4 (p = 0.04), respectively, while glaucoma medications decreased significantly by 1.4 ± 0.5 (p = 0.02) in the long duration group only. Reduction of medications after short duration cyclophotocoagulation was less and did not reach statistical significance (0.9 ± 0.9, p = 0.15). There was no significant difference of visual deterioration and complication rates. Conclusion: Both types of cyclophotocoagulation were equally effective in lowering intraocular pressure by 6 months, but the short duration protocol, using higher laser power, was able to achieve a greater and earlier reduction, at 3 months. However, the long duration protocol, using less laser power, appears better at reducing medication requirement by 6 months.