To compare the functional and structural effects of ranibizumab versus macular laser therapy in patients with center-involving diabetic macular edema.

Prospective, randomized, single-masked clinical trial.

Setting: Single center. Study Population: Thirty-three eyes of 33 patients with center-involving diabetic macular edema, with best corrected visual acuity of 55 to 79 Early Treatment Diabetic Retinopathy Study letters at baseline, completing the 48-week study period. Intervention: Subjects were randomized 2:1 to 3 loading doses of ranibizumab then retreatment every 4 weeks as required; or macular laser therapy at baseline, repeated as required every 12 weeks. Exploratory Outcome Measures: Structural imaging studies included greatest linear dimension and area of foveal avascular zone, perifoveal capillary dropout grade, and presence of morphologic features of diabetic macular edema on Spectralis optical coherence tomography (Heidelberg Engineering GmbH, Heidelberg, Germany). Functional measures: Visual acuity, retinal sensitivity in the central 4 and 12 degrees on microperimetry, color contrast sensitivity protan and tritan thresholds, pattern and full-field electroretinogram amplitudes and implicit times, and multifocal electroretinogram amplitude distribution. These were reported at 12, 24, and 48 weeks.

Ranibizumab-treated subjects gained 6.0 vs 0.9 letters lost for laser, demonstrated improved tritan and protan color contrast thresholds, and improved retinal sensitivity. Electrophysiologic function also improved after ranibizumab therapy. No safety issues were evident. Better retinal thickness reduction and structural improvement in optical coherence tomography features of diabetic macular edema were seen with ranibizumab therapy than in the laser group. There was no evidence of progressive ischemia with ranibizumab therapy.

Ranibizumab therapy in the treatment of diabetic macular edema seems to improve retinal function and structure as demonstrated by this evaluation of different assessment methods.