| Purpose The aim of this prospective study was to establish the normal reference values of macular neurosensory retinal thickness and P1-wave amplitude density and latency period of multifocal electroretinogram in healthy volunteers from 45 to 60 ages in our laboratory. To investigate the changes in the P1-wave latency period and response density of multifocal electroretinogram using different diabetic macula edema scales.Methods To establish a normal reference value for the optical coherence tomography and mfERG, in healthy volunteers from 45 to 60 ages, then 192 eyes of 97 patients with diabetes mellitus were examined using OCT and mfERG.. The thickness of the retinal neuroepithelial layer in the macula region was measured using OCT and the values were compared between healthy and diabetic samples. According to the test results and standardization of the international clinical diabetic macular edema disease severity scales, the diabetic eyes were divided into different DME scales. After mydriasis and topical anesthesia, diabetic eyes were examined using mfERG and the detection values of the first-order kernel of mfERG P1-wave were compared with the corresponding normal reference values. The relationship between the changes in the P1 latency period and response density of mfERG and the diabetic macular edema scores was estimated.Results The macular neurosensory average thickness for the optical coherence tomography were messured into nine sections, and the latency period and response density of multifocal ERG were tested from ring one to ring five, then the normal reference value in healthy volunteers from 45 to 60 ages were established. The DME classification for the 192 eyes examined is listed as follows: 61 cases had no apparent DME, 44 cases displayed mild DME, 48 cases had moderate DME and 39 cases showed severe DME. For the eyes with no apparent DME, the amplitude density of ring one was 60.95±18.25nv/deg2 (P<0.05, healthy vs. diabetic). For the cases of mild DME, the amplitude density of ring one was 55.37±15.08nv/deg2, the amplitude density of ring two was 34.04±9.86nv/deg2 and the amplitude density of ring three was 23.27±4.51nv/deg2 (all P<0.05, healthy vs. diabetic). In the samples that displayed moderate DME, the latency period of ring one was 49.32±4.03ms, the amplitude density of ring one was 29.70±9.91nv/deg2, the latency period of ring two was 46.20±3.81ms, the amplitude density of ring two was 20.16±6.37nv/deg2, the amplitude density of ring three was 14.76±3.88nv/deg2, the amplitude density of ring four was 12.01±2.92nv/deg2, the amplitude density of ring five was 10.47±2.81nv/deg2 (P<0.05, healthy vs. diabetic). For eyes with severe DME, the latency period of ring one was 49.99±5.16 ms, the amplitude density of ring one was 23.44±9.39 nv/deg2, the latency period of ring two was 48.34±4.34 ms, the amplitude density of ring two was 19.98±5.33nv/deg2, the latency period of ring three was 45.64±3.99ms, the amplitude density of ring three was 13.07±3.87nv/deg2, the latency period of ring four was 44.53±4.07ms, the amplitude density of ring four was 11.59±3.22 nv/deg2 (P<0.05), the amplitude density of ring five was 8.88±2.27nv/deg2 (P<0.05, healthy vs. diabetic).Conclusions The OCT may quantitatively measure the macular thickness and accurately stage the DME scales, the mfERG P1-wave latency period was delayed and the response density was decreased between the different stages of DME. OCT combined mfERG provide us early precaution means for the diabetic maculopathy which would allow us to take early interventions to prevent the decline of visual function caused by diabetes mellitus.
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