AIM: To investigate the changes of first order kernel(FOK)and second order kernel(SOK)of multifocal electroretinogram(mf-ERG)in detecting the early retinal abnormalities in sub-clinical stage of diabetic retinopathy.

METHODS: Totally 32 patients(58 eyes)with type 2 diabetes mellitus(DM)without apparent diabetic retinopathy(DR)were detected by mf-ERG, from June 2014 to May 2015. Thirty cases(60 eyes)of normal control group had also been taken to compare the difference of the amplitude and latency between the two groups.

RESULTS: Compared with the control group: there was no statistical difference in the FOK b-wave latency of the diabetic group, and the FOK b-wave amplitude was significantly decreased(t=3.099, P=0.012). The SOK b-wave latency in diabetes group was statistically delayed(t=2.643, P=0.025), and the SOK b-wave amplitude statistically decreased(t=4.833, P<0.01). There was no statistically difference in the a-wave latency and amplitude of FOK and SOK. The b-wave amplitude of FOK and SOK was negatively correlated with the course of the disease. However, the b-wave amplitude was not statistically correlated with the duration of diabetes mellitus.

CONCLUSION: The function of the post-polar outer and inner retina detected by FOK and SOK had been damage even before retinopathy. The anomaly is mainly reflected by the decreasing amplitude of b-wave.