Lower energy levels adequate for effective transcleral diode laser cyclophotocoagulation in Asian eyes with refractory glaucoma

Abstract

Purpose: To study the treatment parameters for diode laser cyclophotocoagulation (DLCP) in Asian Indian eyes using laser energy titrated to clinical response. Methods: This prospective interventional longitudinal study included 66 eyes of 66 patients with varied aetiology refractory glaucoma, no previous cycloablation, and minimum 1 year follow-up. DLCP was performed using the Oculight® Diode laser system (IRIS© Medical Instruments Inc., CA, USA). Power used per spot was titrated according to the audible 'pops' indicating tissue microexplosion. The mean laser energy delivered, post-laser intraocular pressure (IOP) reduction, complications, and requirement of re-treatment in various subgroups were analyzed. Differences in energy delivered in each subgroup were assessed by analysis of variance with post hocBonferroni corrections. Linear regression analysis was used to identify possible predictive factors for failure of cyclodiode therapy. Results: The mean total energy delivered per eye was 87.80±31.8J (range 105.4±36.8J in neovascular glaucoma (NVG) to 61.5±8.8J in uveitic glaucoma (P=0.134)). Mean pre treatment IOP was 36.4±10.7 mmHg, which reduced to 19.4±9.8 mmHg (P<0.001) at 1 week, and 15.6±6.6 mmHg at 1 year. At 1 year, 58 of 66 patients had IOP<22.0 mmHg (response rate 87.8%), and six patients had hypotony (success rate 78.8%). The uveitic glaucoma group had 100% success rate. NVG group required maximum re-treatments. Conclusions: DLCP with a titrated energy protocol needs resulted in lower energy in Asian Indian eyes compared to that reported in literature, and different energy levels are needed for different diseases. 'Standard treatment parameters' for DLCP may be inappropriate for all diseases and all races.