REGIONAL RETINAL BLOOD-FLOW REDUCTION FOLLOWING HALF FUNDUS PHOTOCOAGULATION TREATMENT

Regional changes in retinal blood flow following inferior and subseque nt superior argon laser half fundus photocoagulation treatment were me asured in six diabetic patients with advanced retinopathy. Centreline blood velocity, vessel diameter, and blood flow in major inferior and superior temporal retinal arteries were measured at baseline and follo wing each treatment using the bidirectional laser Doppler technique an d monochromatic fundus photography, Inferior fundus laser treatment pr oduced a significant blood how decrease in inferior temporal arteries ranging from 60% to 78%. Blood flow changes in superior temporal arter ies were not significant, ranging from -7% to +14%. Subsequent superio r fundus laser treatment produced a significant blood how decrease in superior temporal arteries ranging from 50% to 66%. Subsequent blood f low changes in inferior temporal arteries were not significant, rangin g from -19% to +21%. The results indicate that regional laser treatmen t produces a regional reduction in retinal blood how, consistent with measurements of preretinal and intraretinal oxygen tension which have indicated increases in oxygen over photocoagulated regions.