Intravitreal bevacizumab (Avastin) therapy for persistent diffuse diabetic macular edema

Abstract

Purpose: To evaluate the efficacy of bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA) for the treatment of diabetic macular edema.

Methods: This prospective, consecutive, noncomparative case series included 51 consecutive patients (26 females and 25 males; mean age, 64 years) with diffuse diabetic macular edema. Inclusion criteria were determined independently of the size of edema, retinal thickness, visual acuity, age, metabolic control, type of diabetes, or previous treatments beyond a 6-month period. At each visit, patients underwent complete eye examination, including determination of best-corrected visual acuity, slit-lamp examination, intraocular pressure measurement, stereoscopic biomicroscopy of the macula, retinal thickness measurement by optical coherence tomography, fluorescein angiography, and fundus photography. After written informed consent was obtained, all patients were treated with a 0.05-mL injection containing 1.25 mg of bevacizumab.

Results: All patients completed 6 weeks of follow-up; 23 (45%) completed 12 weeks of follow-up. Sixteen patients (70%) had received at least two intravitreal injections. All patients had undergone previous treatments, such as focal laser therapy (35%), full-scatter panretinal laser therapy (37%), vitrectomy (12%), and intravitreal injection of triamcinolone (33%). The mean diameter of the foveal avascular zone was 503 micro m, with 49% with values of >500 micro m. At baseline, mean visual acuity +/- SD was 25.88 +/- 14.43 ETDRS letters (0.86 +/- 0.38 logMAR of Snellen letters). Mean central retinal thickness by optical coherence tomography +/- SD was 501 +/- 163 micro m (range, 252-1,031 micro m). Mean visual acuity +/- SD increased to 0.75 +/- 0.37 logMAR of Snellen letters at 6 weeks after injection (P = 0.001), with some regression to 0.84 +/- 0.41 logMAR of Snellen letters after 12 weeks. Changes in ETDRS letters were not significant throughout follow-up. Mean retinal thickness +/- SD decreased to 425 +/- 180 micro m at 2 weeks (P = 0.002), 416 +/- 180 micro m at 6 weeks (P = 0.001), and 377 +/- 117 micro m at 12 weeks (P = 0.001). Changes of retinal thickness and visual acuity correlated weakly (r = -0.480 and P = 0.03 at 6 weeks; r = -0.462 and P = 0.07 at 12 weeks). The increase of visual acuity after 6 weeks as measured by ETDRS charts could be predicted best by baseline visual acuity. No other factors investigated, such as age, thickness by optical coherence tomography, or previous treatments, were predictive for the increase in visual acuity.

Conclusion: Even in cases of diffuse diabetic macular edema not responding to previous treatments such as photocoagulation, intravitreal injection of triamcinolone, or vitrectomy, improvement of visual acuity and decrease of retinal thickness could be observed after intravitreal injection of bevacizumab. Although our follow-up period was too short to provide specific treatment recommendations, the short-term results encourage further prospective studies with different treatment groups and longer follow-up.