Purpose: To evaluate structure and function improvement in central retina by optical coherence tomography (OCT) and multifocal electroretinography (mf-ERG) in diabetic macular edema (DME) patients after intravitreal injection of ranibizumab (IVR) treatment.
Methods: Twenty-seven eyes in 27 patients with DME received three consecutive monthly injections of IVR (0.05 ml, 10 mg/ml) and as needed thereafter. The clinical parameters of best-corrected visual acuity (BCVA), central foveal thickness (CFT) and mf-ERG were monitored for 6 months before and after IVR. The findings at baseline, 1, 3 and 6 months were analyzed. Correlation and regression analyses were performed on BCVA, CFT, mf-ERG amplitude and implicit time of the N1 and P1 waves.
Results: IVR significantly improved visual acuity from the beginning of the treatment (P < 0.05). There were significant decreases in the CFT compared with the baseline after IVR (P < 0.05). The mean amplitude of P1 and N1 in the central ring at all examinations increased significantly compared with the baseline (P < 0.05). The mean P1 and N1 implicit times in the central ring were shortened, but not significantly (P > 0.05). There were significant correlations of BCVA with CFT, P1 and N1 amplitudes in the central retina (P < 0.05).
Conclusion: In addition to the improvement in BCVA and the reduction in CFT, IVR improved macular retinal function, as assessed by mf-ERG, in diabetic eyes. The combination of OCT and mf-ERG for macular evaluation may better assess DME.
Keywords: Diabetic macular edema; Mf-ERG; OCT; Ranibizumab.