The prognostic value of post-treatment retinopathy after panretinal photocoagulation for proliferative diabetic retinopathy in type 1 diabetes.

PURPOSE: To study the prognostic value of post-treatment retinopathy after panretinal laser photocoagulation for proliferative diabetic retinopathy in type 1 diabetes mellitus. Proliferative diabetic retinopathy is treated with panretinal photocoagulation, which significantly reduces the risk of visual loss from this complication. However, no parameters are presently known that can be used to define an optimal control interval after the initial panretinal photocoagulation treatment that ensures enhancement of the treatment in cases where this is needed. METHODS: In this retrospective cohort study, 85 eyes from 56 type 1 diabetic patients were identified who had been subjected to panretinal photocoagulation for proliferative diabetic retinopathy before 1990. The patients were divided into two groups: Group 1 had four or fewer microaneurysms only at the first post-treatment examination whereas Group 2 had more retinopathy. RESULTS: At the first photographic examination after treatment the eyes in Group 1 had a significantly lower visual acuity (VA) (mean =0.23, range: 0.01-1.00) than the patients in Group 2 (mean=0.48, range: 0.01-1.6). During the follow-up period the VA was further reduced in Group 2 but not in Group 1. Three eyes out of six in Group 1 had improvement of VA from below to above 0.1, whereas 6 eyes out of 12 in Group 2 experienced progression of retinopathy with a consequent worsening of VA to below 0.1 after a mean of 10.8 years (range: 6.8-15.9) after treatment. CONCLUSIONS: The severity of post-treatment retinopathy can be used to assess the need for enhancing photocoagulation of proliferative diabetic retinopathy in type 1 diabetes. The interval between post-treatment examinations can be increased to several years when the initial treatment has reduced retinopathy to a minimal level.