Electrophysiological and Structural Assessment in Retinal Vein Occlusion with Macular Edema Following Repeated Intravitreal Bevacizumab Injection

Abstract

Purpose: : To investigate electrophysiological and structural response after repeated intravitreal injections of bevacizumab for macular edema attributable to retinal vein occlusion, prospectively.

Methods: : Thirty-six eyes of 36 patients with macular edema attributable to central retinal vein occlusion (CRVO) in 19 patients and branch retinal vein occlusion (BRVO) in 22 patients received three times of intravitreal injections of bevacizumab 1.25mg at 6-week intervals. Complete ophthalmic examinations including full-filed electroretinography (ffERG) and optical coherence tomography (OCT) were conducted before treatment and 4 weeks after each injections. Pre-treatment measurements of affected eyes were compared with that of unaffected fellow eyes with paired samples T-test. The differences between pre-treatment measurements and each post-treatment measurement of affected eyes were analyzed with repeated-measures ANOVA test. Post-hoc analysis was conducted via Bonferroni test.

Results: : LogMAR visual acuity (VA), central retinal thickness (CRT) and ffERG parameters were worse significantly in affected eyes compared to unaffected eyes. VA was improved significantly from 0.96 ± 0.20 before treatment to 0.48 ± 0.39 after the 1^st injection (P=0.031). Though, VA was continually improved to 0.39 ± 0.13 and 0.25 ± 0.07 after the 2^nd and 3^rd injections respectively, the differences did not reach statistical significance. CRT was decreased significantly from 640.85 ± 53.99µm before treatment to 333.85 ± 67.91µm after the 1^st injection (P=0.000). After the 2^nd and 3^rd injections, CRT was 288.57 ± 38.30µm and 314.57 ± 40.30µm and the differences were not significant. None of the scotopic or photopic ERG parameters were evidenced significant changes between before and after the treatments. There was no significant difference in subgroup analysis between BRVO and CRVO.

Conclusions: : Three repeated injections of bevacizumab appear to result in significant improvement of VA and macular edema secondary to retinal vein occlusion. However, repeated injections of bevacizumab do not affect the electrophysiological retinal function.

Keywords: electroretinography: clinical • retina