In diabetic eyes, multifocal ERG reflects differences in function between the nasal part and the temporal part of the...

The purpose of the present study was to compare retinal function between the perifoveal nasal and perifoveal temporal areas of diabetic eyes using multifocalERG (mfERG).

We included 36 eyes from 27 patients with diabetes (age 58 ± 14 years; duration of diabetes 13 ± 9 years; HbA(1c) 7.1 ± 1.8%) and a control group with 18 eyes from 18 healthy subjects (age 57 ± 11 years). Retinal thickness was assessed with optical coherence tomography (OCT) in the perifoveal areas corresponding to the summed nasal and temporal inner and outer areas. MfERG amplitude and implicit time were recorded from corresponding areas.

Diabetic eyes showed lower mfERG amplitude in the nasal area than in the temporal area (14 ± 6 vs 17 ± 7 nV/deg(2); p < 0.0001) and longer implicit time (31 ± 3 vs 30 ± 3 ms; p = 0.005). In the control group, there were no significant differences between the two areas.

Diabetic eyes showed lower amplitude and longer implicit time in the nasal area than in the temporal, which might indicate that the nasal area is more vulnerable. These findings may be of importance for evaluation of diabetic maculopathy and outcome after laser treatment.