TRANSSCLERAL DIODE LASER CYCLOPHOTOCOAGULATION FOR THE TREATMENT OF ABSOLUTE GLAUCOMA IN DOGS

Abstract

Diode laser transscleral cyclophotocoagulation (TSCP) for the treatment of absolute glaucoma, is a noninvasive procedure which induces coagulation necrosis to the ciliary epithelium by laser light to reduce aqueous humor production. This study was to assess outcomes using TSCP in dogs with absolute glaucoma. Location of pars plicata in 12 buphthalmic canine globes was anatomically studied. Mean distance from limbus to posterior border of pars plicata was ranged from 4.44 ± 0.74 to 6.11 ± 0.73 mm. Diode laser TSCP at a setting of 1500mW power and 1500ms duration was performed on 31 eyes of 26 dogs diagnosed with absolute glaucoma. Laser probe was applied in 64 spots, 360 degrees around the globe at 3, 4 and 5 mm distance posterior to the limbus. 71.97% of ‘pop’ sounds were observed. Mean IOP significantly reduced from 62.1 ± 2.5 to 6.6 ± 1.0 mmHg by the end of the study. Axial globe length was significantly decreased, comparable to that of normal eyes. Significant reduction in numbers of topical hypotensive application was first observed at day 21 post TSCP. Hypotony was the most frequent complication, followed by superficial corneal ulcer and hyphema. Six eyes that were histologically examined revealed coagulative necrosis of ciliary body. Tissue separation and disruption were demonstrated if overheated. This laser protocol was suitable as a treatment for canine absolute glaucoma. Qualified success in accordance with IOP level of less than 20 mmHg was 96.77% and clinical complications were controllable.