Structural and Functional Correlates of Macular Laser Photocoagulation in Diabetic Maculopathy

Abstract

Purpose: : To assess the effect of focal macular laser photocoagulation on retinal structure and on photopic and scotopic retinal function in patients with clinically significant diabetic macular oedema.

Methods: : Ten patients with clinically significant diabetic macular oedema (as per ETDRS criteria) were examined. Structural changes were assessed using fluorescein angiography (FA), fundus autofluorescence (AF) and optical coherence tomography (OCT). Macular function was assessed objectively using ISCEV–standard Pattern ERGs (PERG). Fine matrix mapping (FMM) was used to measure photopic and scotopic thresholds over treated and untreated macular areas. All tests were repeated four months following laser treatment.

Results: : Macular oedema resolved in all cases following laser coagulation according to FA. Three patients showed persistent intraretinal fluid on OCT. AF remained stable in all cases. All the patients had BCVA of 20/20 following treatment. Pattern ERG P50 improved in 7 of 8 treated eyes (mean increase 34%). Photopic thresholds were stable or showed marginal improvement (average 0.2 log units) in all but 1 treated eye; scotopic thresholds decreased by an average of 0.8 log units in 5 out of 9 treated eyes. Improvements in sensitivity occurred over treated and remote macular locations.

Conclusions: : Reduced oedema may be accompanied by improved macular function over areas significantly larger than those treated. Scotopic retinal sensitivity shows marked improvement in most cases.

Keywords: electroretinography: clinical • clinical (human) or epidemiologic studies: systems/equipment/techniques • diabetic retinopathy