Comparison of the Effects of Bevacizumab Before vs After Pattern Panretinal Photocoagulation

Abstract

Purpose: : To compare the effect of an intravitreal injection of bevacizumab before vs. after panretinal pattern-laser photocoagulation (PRLP) with PASCAL and to prevent and reduce diabetic macular edema (DME) in patients with proliferative diabetic retinopathy (PDR).

Methods: : Fifteen patients with clinical diagnosis of PDR were randomized into two groups: 9 patients were treated with intravitreal injection of bevacizumab prior to PRP (group A); 6 patients were treated with intravitreal injection of bevacizumab after PRP (group B). The initial exam included the best corrected visual acuity (BCVA) by ETDRS protocol, contrast sensitivity and color exams, electroretinogram (ERG), optic coherence tomography (OCT), fluorescein angiography (FA), and an indirect fundus examination. Follow-up examinations were done at days 10, 52, 85.

Results: : The visual acuity registered in group A at 10 days improved a mean of 4 letters, 3.6 letters at 52 days, and 5.6 letters at day 85 (p>0.05). The visual acuity in group B decreased at 10 day follow-up visit by a mean of -1 letter, and the VA improved at 52 days follow-up by a mean of 9 letters. 100% of the patients in group A, that started with abnormal ishihara test maintained abnormal results throughout, on the other hand, in group B 100% of the patients that started with abnormal exams finished with normal exams. In the farnsworth Munsen examination group A, 60% of the patients started with a tritanomaly and finished with a tritanomaly, 40% maintained normal studies. In group B, 50% presented changes from normal to tritanomaly and 50% with protanomaly, this was maintained until the end of the study. The contrast sensitivity in group A was improved by 0.35 in 40% of the patient population, 40% showed a decreased of 0.25. In group B, 100% of the patients showed a decreased of 0.5 to -1.25. In both groups the "a" and "b" wave decreased in 100% of the ERGs, and increased in the implicit time. Optical coherence tomography in group A macular thickness and volume decreased a mean of 153µm, and 2.0mm³, in group B macular thickness and volume decreased a mean of 109µm, and 1.18 mm³.

Conclusions: : It is better to use an intravitreal injection of bevacizumab after PRP where the visual acuity improvement was demonstrated to be p<0.05. In other studies there was no statistical difference shown.

Keywords: diabetic retinopathy • edema • laser