Clinical, anatomical, and electrophysiological assessments of the central retina following intravitreal bevacizumab for macular edema secondary to retinal vein occlusion

The purpose of this study is to evaluate the long-term visual, anatomical and electrophysiological outcomes of repeated intravitreal injections of bevacizumab for macular edema due to retinal vein occlusion (RVO) and investigate any possible toxic effects on the central fovea. This is a prospective, noncomparative, interventional case series. Thirty-three eyes of 33 patients with macular edema secondary to RVO were treated with 1.25 mg/0.05 ml intravitreal bevacizumab. Nine patients had nonischemic central retinal vein occlusion (CRVO) and 24 patients had branch retinal vein occlusion (BRVO). The main outcome measures were best-corrected visual acuity, central retinal thickness (CRT), and multifocal electroretinography (mfERG) responses changes at baseline, 1 month after the third injection and at the end of the 2-year long follow-up period. Patients with CRVO had mean best-corrected Snellen visual acuity of 0.10 at baseline, which improved significantly to 0.31 after 2 years (P = 0. 028).The mean CRT at presentation was 756.28 mu m and reduced significantly to 439.14 mu m after 2 years (P = 0.05). Patients with BRVO had mean best-corrected Snellen visual acuity of 0.19 at baseline, which improved significantly to 0.40 after 2 years (P < 0.001). The mean CRT at presentation was 681.04 mu m and reduced significantly to 369.81 mu m after 2 years (P < 0.001). Mean mfERG responses within central 10A degrees (ring1, ring2) showed statistically significant differences on P1 parameters in terms of response density and implicit time after 2 years in both CRVO and BRVO patients. Repeated intravitreal bevacizumab injections for macular edema due to either CRVO or BRVO resulted in long-term improvement of visual acuity, a reduction in CRT and statistically significant changes in the mfERG responses with nondemonstrable toxic effects on the central fovea.