Objective:To investigate the damage of visual function in the early stage of diabetes mellitus and the response characteristics of primary visual cortex neurons in diabetic mice.Methods:Twenty 7-week-old SPF grade male C57BL/6J mice were randomly divided into diabetes group and normal control group by the random number table method, with 10 mice in each group.The diabetes model in diabetes group was established by the intraperitoneal injection of streptozotocin.Fasting blood glucose concentration and body mass of mice were measured before and 1, 2 and 3 weeks after modeling, and intraperitoneal glucose tolerance test was performed 4 weeks after modeling to evaluate the establishment of diabetes model.At 4 weeks after modeling, the electroretinogram (ERG) responses of mice were recorded at dark adaptation luminances of 0.01 and 3.0 cd·s/m 2, and the ERG response to light adaptation luminance of 3.0 cd·s/m 2 was recorded 10 minutes after light adaptation to evaluate the retinal function of mice.The fundus of mice was examined with an ultra-wide field laser scanning ophthalmoscope.The visual function of mice was evaluated via the cutoff frequency of grating discrimination detected by visual water maze.The spatial frequency tuning curves of primary visual cortex (V1) neurons were detected by in vivo electrophysiology technique and the maximum firing intensity, self-firing intensity, optimal spatial frequency, cutoff frequency and bandwidth of neurons were calculated to evaluate the neuronal function of mice.The research scheme was approved by the Experimental Animal Ethics Committee of Anhui Medical University (No.LLSC20230419). Results:The diabetic model was successfully established in 10 mice in the diabetes group.At 4 weeks after modeling, compared with the normal control group, the b-wave amplitudes of mice at a dark adaptation luminance of 0.01 cd·s/m 2, the a- and b-wave amplitudes of mice at a dark adaptation luminance of 3.0 cd·s/m 2 and the b-wave amplitudes of mice at a light adaptation luminance of 3.0 cd·s/m 2 after 10 minutes of light adaptation showed a downward trend in diabetes group, but the differences were not statistically significant (all at P>0.05).Ultra-wide field laser scanning ophthalmoscopy showed no obvious vascular changes in the retina of diabetic mice.The results of visual water maze detection showed that the cutoff frequency of diabetes group was (0.45±0.06)c/d, which was significantly lower than (0.58±0.05)c/d of normal control group ( t=5.10, P<0.05). In vivo electrophysiological results showed that the maximum firing intensity of neurons in V1 region in diabetes group 4.29(2.60, 8.33)spikes/second, which was significantly lower than 7.10(4.34, 11.6)spikes/second in normal control group( Z=-4.29, P<0.05).The optimal spatial frequency, cutoff spatial frequency and bandwidth were 0.03(0.02, 0.05), 0.07(0.05, 0.12) and 0.14(0.07, 0.22)c/d in diabetes group, which were significantly lower than 0.41(0.03, 0.05) and 0.10(0.07, 0.14), 0.14(0.10, 0.26)c/d of normal control group, and the differences were statistically significant ( Z=-3.22, -3.19, -2.19; all at P<0.05). Conclusions:The abnormal visual function may occur in the early stage of diabetes before the appearance of retinal vasculopathy, which is related to the damage of neurons in the V1 region.

Objective: To investigate the effect of obstructive sleep apnoea-hypoapnoea syndrome(OSAHS)on diabetic retinopathy(DR)in elderly patients with type 2 diabetes mellitus(T2DM)and analyze risk factors for DR process. Methods: Data of elderly diabetic patients without DR admitted into our hospital from January 2012 to December 2014 were retrospectively analyzed.Based on whether or not to combine OSAHS, patients were divided into the OSAHS group(n=42)and the control group(n=85). After 36 months' follow-up, the incidence and progression of DR were compared, and the effect of different degree of OSAHS on DR was analyzed.Multivariate logistic regression analysis was used to analyze the risk factors for DR. Results: The systolic pressure, diastolic pressure and Epworth sleepiness scores were higher in the OSAHS group than in the control group(P<0.05). At the(34.5±6.7)months of follow-up versus baseline, body mass index, renal function and cardiac function were markedly decreased in both groups(P<0.05). The systolic pressure, diastolic pressure, 2-h postprandial blood glucose and Epworth sleepiness scores were higher in the OSAHS group than in the control group; and the glomerular filtration rate(GFR)and left ventricular ejection fraction were lower in the OSAHS group than in the control group(P<0.05). The incidences of mild, moderate and severe non-proliferative DR were higher in the OSAHS group than in the control group(P<0.05). The results of subgroup analysis showed that the incidence of DR was higher in patients with moderate to severe OSAHS than in controls(OR=4.57, 95%CI: 1.24~13.78, P=0.002), while the incidence of DR in patients with mild OSAHS was similar to that in the controls(OR=2.33, 95%CI: 0.66~12.56, P=0.29). Multivariate logistic regression analysis showed that T2DM duration ≥7 years(OR=3.24, 95%CI: 1.80-9.59, P<0.05), haemoglobin A1c(HbA1c)≥7.5%(OR=2.07, 95%CI: 1.41-8.52, P<0.05), GFR<60 ml/min(OR=4.52, 95%CI: 1.75-14.26, P<0.05)and apnea/hyponea index ≥15/h(OR=2.03, 95%CI: 1.37-11.24, P<0.05)were independent risk factors for DR. Conclusions OSAHS patients tend to have hypertension and high glucose level, and are more prone to cardiac and renal dysfunction and DR.T2DM duration ≥7 years, HbA1c ≥7.5%, GFR<60 ml/min and AHI ≥15/h are independent risk factors for DR progression.And more studies are needed to confirm the independent risk factors.