Randomized comparison of Krypton versus Argon scatter photocoagulation for diabetic disc neovascularization : the Krypton Argon regression neovascularization study report number 1

The Krypton Argon Regression of Neovascularization Study (KARNS) was designed to compare the efficacy of red krypton versus blue-green argon laser photocoagulation for the management of high-risk proliferative diabetic retinopathy. A prospective, randomized clinical trial was performed in 24 clinical centers. Patients (n = 696, 907 eyes) with diabetes and neovascularization of the disc (NVD) of one-third disc area or greater in extent were assigned at random to either argon or krypton laser scatter (panretinal) photocoagulation. The major endpoint of the regression of NVD to less than one-third disc area in extent at 3 months was evaluated by comparisons of gradings of the fundus photographs obtained at baseline and follow-up. At 3 months' follow-up, the proportion of eyes with regression of NVD to less than or equal to one-third disc area in extent were 41.1% in the argon-treated group and 41.8% in the krypton-treated group (P = 0.92). The odds of regressing to this extent of NVD at 3 months for argon-treated eyes versus krypton-treated eyes was 0.98 (95% confidence interval, 0.74-1.31). Scatter laser photocoagulation with either krypton red or argon appears to be equally effective in the treatment of proliferative diabetic retinopathy with NVD.