To evaluate multifocal electroretinogram (mfERG) parameters in eyes with diabetic macular edema (DME) and its correlation with vision and optical coherence tomography (OCT) features.

Fifty-four eyes of 27 subjects with DME due to non-proliferative diabetic retinopathy were evaluated. MfERG responses in three concentric rings were measured. Macular thickness was measured by OCT in each segment of the concentric rings and mfERG rings were superimposed on macular thickness map. Correlation between VA, localized macular thickness, and retinal structural abnormalities with mfERG parameters at each segment was evaluated.

Mean of BCVA was 0.5 ± 0.3 in logMAR and central macular thickness was 392.6 ± 123.4 microns. The central ring P1 and N2 amplitude were both significantly correlated with BCVA in univariate and multivariate analysis (P=0.001). Retinal thickness was correlated significantly with N1 amplitude in central ring (p=0.02). Outer retinal layer disruption (ELM and ellipsoid zone) was correlated with prolonged P1 implicit time at corresponding location (p=0.005). Disorganization of retinal inner layers (DRIL) was associated with reduced P1 and N2 amplitude (p=0.037 and p=0.019 respectively). Presence of cyst was correlated with lower central P1 amplitude (p=0.033).

Central retinal thickness or different OCT biomarkers (as an anatomical indicator of diabetic macular edema) can be correlated with different mfERG features. Predictive models such as those described in this report, may make it possible to identify correlation of specific anatomic and functional characteristics in diabetic macular edema.