Breakdown of the Blood-aqueous Barrier after Laser Retinal Photocoagulation

Abstract

Abstract: : Purpose: To study and to compare breakdown of the blood-aqueous barrier after laser photocoagulation of peripheral retina or posterior pole in different pathological conditions using a laser-flare-meter. Methods: 80 eyes of 80 patients were included in this prospective study. A frequency-doubled Nd:YAG laser was used for all patients. 63 patients underwent peripheral retinal photocoagulation : 25 had proliferative diabetic retinopathy, 38 had previously operated retinal detachment. Each patient received 120 to 1000 burns in one single procedure. Power levels were ajusted to produce a mild blanching of the retina.17 patients suffering from clinically significant macular edema (12 patients) or perifoveolar neovascular membrane (5 patients) underwent posterior retinal photocoagulation ; 30 to 230 burns were delivered in one single procedure. Laser photometry was performed on both eyes before and 7 and 28 days after treatment. Results: There was a significant increase in flare values at 7 days in both groups of peripheral retinal photocoagulation compared to baseline (Student's paired t test) but the increased flare was sustained at 28 days only in the diabetic retinopathy group. A significant difference of evolution was found between the diabetic retinopathy group and the retinal detachment group (Repeated Measures ANOVA). A significant correlation was found between the number of burns and the increase in flare values (Pearson's test). The increase in flare values was significantly highier in pseudo-phakic eyes than in phakic ones. No significant difference was found in flare values at 7 or 28 days compared to baseline in the posterior retinal photocoagulation group (Student's paired t test). Conclusions: A significant increase in aqueous flare was found 7 days after peripheral retinal photocoagulation. Flare values returned to baseline at 28 days in patients previously operated for retinal detachment whereas they remained elevated in patients with proliferative diabetic retinopathy. No significant variation of aqueous flare was found 7 or 28 days after posterior pole photocoagulation for clinically significant macular edema or neovascular membrane.

Keywords: laser • diabetic retinopathy • retinal detachment