AIM:To study the retinal function of macular edema of diabetic retinopathy.

METHODS: Thirty cases(48 eyes, 18 eyes of local macular edema, 24 eyes of diffuse macular edema and 6 eyes of cystoid macular edema)and fifteen normal cases(30 eyes)were enrolled in the study. Multifocal electroretinogram(mfERG)system(version 3.15)was used and the recordings were evaluated.

RESULTS: Compared with the control group, a-wave and b-wave amplitude densities at the fovea, the macula and paramacular of diabetic macular edema(DME)retina were attenuated(P<0.01). The amplitude densities of a-wave at the fovea of two groups were 25.2±10.48 nv/deg² and 37.93±7.19 nv/deg². The amplitude densities of b-wave at the fovea of two groups were 77.16±27.97nv/deg² and 113.42±11.79nv/deg². The amplitude densities of a-wave at the macula of two groups were 14.27±4.99 nv/deg² and 27.42±2.86 nv/deg². The amplitude densities of b-wave at the macula of two groups were 43.14±14.77nv/deg² and 69.99±10.07 nv/deg². The amplitude densities of a-wave at paramacular of two groups were 7.82±2.79nv/deg² and 11.46±1.54nv/deg². The amplitude densities of b-wave at paramacular of two groups were 19.85±6.5nv/deg² and 31.56±6.0nv/deg². There were significant difference in a-ware amplitude density and b-ware amplitude density among three groups(local macular edema, diffuse macular edema and cystoid macular edema)(P<0.01). There were no significant differences in a-ware latency and b-ware latency among three groups(P>0.05).

CONCLUSION: The amplitude densities of a-wave and b-wave of DME retina are attenuated. The latency of a-wave and b-wave are longer. The amplitude densities are more sensitive than the latency.