AIM: To analyze the changes in contrast sensitivity of macular nerve fiber layer and visual function and macular visual field in diabetic patients before diabetic retinopathy.

METHODS: Case-control study, from Jan 2015 to Jan 2017 choose 59 cases of type 2 diabetes without diabetic retinopathy were selected as the observation group, 40 normal persons and 40 patients with mild non-proliferative diabetic retinopathy were selected as the control group. The morphology of the nerve fiber layer in the macular area, the contrast sensitivity of visual function, and the threshold of macular field were compared and analyzed.

RESULTS: The average thickness of the fovea(FT)in normal group, DR0 group and DR1 group were 244.45±22.863, 237.53±18.240, 240.78±23.946μm. There was no statistically significant difference in the average FT, retinal nerve fiber layer thickness in foveal central field(RNFL-C), RNFL thickness in perifovea among the three groups(P>0.05). The foveal volume(FV), RNFL thickness in parafove between the three groups was statistically significant(P<0.05). Visual function contrast sensitivity test: the differences in contrast sensitivity of normal group, DR0 group and DR1 group at 3, 6, 12, 18c/d spatial frequency were statistically significant(P<0.05). Visual function of macular field: the difference in visual acuity threshold of the macular centers MS, MS1-4, MS5-16, MS1-16 in the normal group, DR0 group and DR1 group is statistically significant(P<0.05).

CONCLUSION: Before diabetic retinopathy, diabetic patients will have macular nerve fiber thinning and fovea volume reduction, visual function contrast sensitivity decline and visual field changes. OCT, contrast sensitivity and visual field examination can be diabetic retinopathy. Early screening and intervention provide important evidence.