[Photocoagulation with the argon laser in cystoid macular edema in retinal venous occlusions. Apropos of 68 cases].

Sixty-eight consecutive eyes with cystoid macular edema due to venous occlusion were treated by grid laser photocoagulation. The diagnosis of cystoid macular edema was based on both the biomicroscopic and angiographic findings. The treatment was applied with blue-green or green argon laser. The criteria for treatment were the presence of cystoid macular edema, visual acuity of 0.5 or less and duration of the venous occlusion for more than 6 months. The technique of treatment included direct photocoagulation of certain microaneurysms and of collateral dilatations exhibiting fluorescein leakage in the macular area, followed by grid photocoagulation applied to the area of cystoid edema. No laser burn was placed within 300 microns of the center of the macula. The patients were followed for periods of 6 to 24 months with a mean follow-up of 15 months. Forty-five eyes presented with a branch vein occlusion. Photocoagulation resulted in the decrease or disappearance of macular edema in 42 of these eyes (93%) and the improvement of visual acuity by 0.2 or more in 12 (27%). Twenty-three eyes presented central vein occlusion. In these cases, photocoagulation resulted in the decrease or disappearance of macular edema in 20 eyes (87%), and visual acuity improved by 0.2 or more in 4 (17%). These results indicate that grid laser photocoagulation is an effective method, reducing persistent cystoid macular edema due to venous occlusion. However, visual results were better in the branch vein occlusions than in the central vein occlusions.