Effects of macular ischemia on the outcome of intravitreal bevacizumab therapy for diabetic macular edema

Purpose: To evaluate the effects of macular ischemia on visual outcomes in patients with diabetic macular edema (DME), after intravitreal bevacizumab injections. Methods: Data on 59 eyes of 53 consecutive patients treated with intravitreal bevacizumab for DME were retrospectively reviewed. Data from preoperative fluorescein angiography (FA) tests were examined. Patients with an enlarged foveal avascular zone (FAZ), >= 1000 mu m, or a broken perifoveal capillary ring at the border of the FAZ, with a distinct area of capillary nonperfusion within one disk diameter of the foveal center in the transit phase of fluorescein angiography, were defined as having macular ischemia. The patients were thus divided into two groups: with or without macular ischemia. Early Treatment Diabetic Retinopathy Study (ETDRS) scores, and foveal thicknesses measured using third generation ocular coherence tomography (OCT), were evaluated at baseline and at 1 month and 3 months after treatment. Results: At 3 months after treatment, the mean visual acuity (VA) score decreased from a baseline VA of 0.52 +/- 0.27 (approximate Snellen equivalent, 20/63) to 0.57 +/- 0.21 (20/80) in the ischemic group. In the nonischemic group, by contrast, the VA improved from 0.66 +/- 0.34 (20/100) at baseline to 0.59 +/- 0.33 (20/80) at 3 months post-treatment. Nine of 18 eyes (50%) in the ischemic group, but only 9 of 41 eyes (21%) in the nonischemic group, experienced visual losses of >= 1 line on the ETDRS chart (P = 0.031, Pearson chi-square test). Four eyes (22%) in the ischemic group, but only 2 eyes (5%) in the nonischemic group, lost >= 3 lines (P = 0.042, Pearson chi-square test). Conclusion: Macular ischemia may have a negative effect on short term visual outcomes after intravitreal bevacizumab injections in patients with DME.