Retinal Vascular Caliber Changes in Diabetic Retinopathy after Panretinal Photocoagulation and Additive Bevacizumab Injections

Abstract

Purpose:To evaluate the effect of panretinal photocoagulation and additive intravitreal bevacizumab injections on central retinal vessel diameters and characteristic retinal vascular caliber changes in diabetic retinopathy. Methods: Changes in central retinal vessel diameters were retrospectively analyzed before and 6 months after panretinal photocoagulation with or without additive intravitreal bevacizumab injections in 64 eyes first diagnosed with diabetic retinopathy. Vessel diameters and arteriovenous ratio (AVR) were measured using Interactive Vessel Analysis (IVAN) software and the Big six formula. Results: There were significant decreases in central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) in both groups, with and without additive intravitreal bevacizumab injections, 6 months after completion of panretinal photocoagulation (p < 0.001, p = 0.008), but no significant change in AVR (p = 0.338). Additive intravitreal bevacizumab injections did not produce significant changes in central retinal vessel diameters after 6 months compared to vessel diameters treated with panretinal photocoagulation only. Retinal vascular caliber of progressed diabetic retinopathy showed smaller CRAE, larger CRVE, and smaller AVR compared to those of normal or diabetic Korean subjects in a previous study and showed no significant association with age. Conclusions: CRAE and CRVE decreased significantly 6 months after panretinal photocoagulation in diabetic retinopathy, but additive intravitreal bevacizumab injections did not cause significant additive changes to central retinal vascular calibers in this study. We established the standard retinal vascular caliber of Korean subjects in diabetic retinopathy and analyzed the effects of retinopathy on retinal vessel caliber. J Korean Ophthalmol Soc 2016;57(6):917-923

Retinal vascular caliber changes after laser photocoagulation in diabetic retinopathy

“…1,3,4 Laser photocoagulation aims to reduce the oxygen demand of the retina for ischemic changes in diabetic retinopathy. 5 After laser photocoagulation, oxygen flow increases from the choroid to the inner retina, causing the constriction of retinal blood vessels. This hypothesis is supported by the possibility that oxygen tension level plays an important role in the autoregulation of retinal blood vessels, in which arterioles dilate when oxygen decreases and constrict when oxygen tension increases.…”