Diabetic Macular Edema Treatment with Bevacizumab vs. Ranibizumab: A Microperimetry Study

Abstract

Purpose: To compare macular sensitivity in patients with diabetic macular edema (DME) treated with intravitreal Bevacizumab (IVB) vs Ranibizumab (IVR) using microperimetry.

Methods: Forty-eight patients (63 eyes) with center-involving DME were randomly assigned to receive either 1.5 mg/0.06 cc IVB or 0.5 mg/0.06 cc IVR. Injections were performed at baseline and monthly if central subfield thickness (CSFT) measured by spectral domain optical coherence tomography (SDOCT) was 275 μm or higher. Evaluations were done monthly, including SDOCT and best-corrected visual acuity (BCVA). Microperimetry (MAIA - CenterVue) was performed before, 3, 6, 9 and 12 months of follow up, to determine the fixation stability (95 % bivariate contour ellipse area - BCEA), and the sensitivity threshold (ST) on 37 test points: a central point, and 3 concentric rings: 1, 3 and 5 degrees from the fixation location, with 12 test points each.

Results: Forty-three patients (61 eyes; IVB n=32; IVR n=29) completed the 12 months follow-up. Significant improvement was observed for BCVA and CSFT within each of the two study groups at all study visits compared to baseline (p<0.05). BCEA was comparable in IVB: 20.2 ± 5.1 and IVR: 23.3 ± 4.8 at baseline (P=0.3334), and no significant improvement was observed for BCEA during follow-up. On the other hand, ST at central ring significantly improved (P<0.05) in all study visits, going from 16.6 ± 1.0 dB, and 15.1 ± 1.0 dB at baseline, to 19.1±1.1 dB and 18.1 ± 1.2 dB at 12 months, for IVB and IVR respectively. The ST improvement was significant at 12 months, but not in all study visits for the external rings 3 and 4 for IVB and IVR. There was no difference for ST improvement between IVB and IVR during follow-up.

Conclusions: Fundus-related microperimetry showed a significant increase in central retinal sensitivity for IVB and IVR in DME, particularly for the internal (1 degree) microperimetry ring. IVB and IVR were not significantly different improving central retinal sensitivity up to 12 months follow-up.

Keywords: 585 macula/fovea • 505 edema • 499 diabetic retinopathy