Photocoagulation of the Retinal Nonperfusion Area Prevents the Expression of the Vascular Endothelial Growth Factor in an Animal Model

Abstract

The purpose of this study was to evaluate whether photocoagulation of the retinal nonperfusion area suppresses ocular vascular endothelial growth factor (VEGF) expression in a rabbit retinal vein occlusion (RVO) model. The retinas of pigmented rabbits were made ischemic by a laser on the main branch of retinal veins following intravenous injection of Rose Bengal. The eyes were enucleated before treatment and at 1, 7, and 14 days after laser occlusion. VEGF protein levels in the vitreous humor, sensory retina, and retinal pigment epithelium-choroid were measured with enzyme-linked immunosorbent assay. In situ hybridization of VEGF messenger RNA was performed to detect the location of VEGF expression in the sensory retina. In the vitreous body, the VEGF protein level in the RVO group, but not that in the RVO + panretinal photocoagulation group, significantly increased on day 14. In the retina, the VEGF protein level in the RVO + panretinal photocoagulation group was significantly higher than that in the RVO group on day 1, but was significantly lower than that in the RVO group on days 7 and 14. In the in situ hybridization analysis, the RVO group showed a high expression of VEGF in the inner nuclear and ganglion cell layers on days 7 and 14. In contrast, VEGF expression in the RVO + panretinal photocoagulation group was strongly suppressed in both the inner nuclear and ganglion cell layers on days 7 and 14. This study is the first using an animal RVO model to demonstrate that laser photocoagulation of the retinal nonperfusion area suppresses VEGF-A expression in the retina.