Analysis Of Ganglion Cell Layer-inner Plexiform Layer Thickness And Related Factors In Mild To Moderate Non-proliferative Diabetic Retinopathy

ObjectiveTo investigate the changes of ganglion cell layer-inner plexiform layer thickness and the relationship between the relevant factors in mild to moderate non-proliferative diabetic retinopathy.And to further provide a new perspective on the pathogenesis and diagnosis of diabetic retinopathy.MethodsOne hundred and two eyes of 102 patients who diagnosed as type 2 diabetes in the Second Affiliated Hospital of Fujian Medical University between July 2017 and March2018 were enrolled as experimental group.Thirty eyes in 30 healthy volunteers of the same age were enrolled as normal control group.According to the results of ophthalmoscopy,the experimental group was further divided into two subgroups:the first one is patients without diabetic retinopathy(NDR,50eyes);the second one is patients with mild to moderate non-proliferative diabetic retinopathy(NPDR,52eyes).The macula and optic disc of all participants were scanned by spectral-domain OCT with 768x496 mode for the sectoral(superior,nasal,temporal,inferior)GCL and IPL in the macula,and rapid scanning mode for the retinal nerve fiber layer(RNFL).The data were then automatically analyzed with the OCT definition of early diabetic retinopathy treatment research.Glycosylated hemoglobinwas measured by automatic glycosylated hemoglobin analyzer,while blood lipid indexes(triglyceride[TG],total cholesterol[TC],high-density lipoprotein[HDL]and low-density lipoprotein[LDL]were detected by automatic biochemical analyzer.One-way ANOVA,?~2test,t test and Kruskal-Wallis H test were used for general data.One-way ANOVA was used to compare GCL-IPL thickness and RNFL thickness.LSD test and Dunnett T3 were used for pairwise comparison between different groups.Spearman analysis was used for correlation analysis.ResultsRNFL thicknesses of three groups were listed as follows.NDR group:(Average,G)105±7.23?m,(Superior,S)131.26±10.34?m,(Nasal,N)74.84±10.34?m,(Inferior,I)136.14±16.90?m,(Temporal,T)77.76±10.47?m;NPDR group:G 104.70±10.34?m,S 129.10±17.60?m,N 72.73±13.73?m,I 136.04±20.18?m,T 81.27±13.48?m;Normal group:G 111.26±6.86?m,S 138.87±14.16?m,N 80.97±12.90?m,I 143.53±12.17?m,T 81.67±11.81?m.The diffference in G,S and N in NDR group were thinner than Normal group(P<0.05).so as to NPDR group and Normal group.The difference of each quadrant between NDR group and NPDR group was not significant(P>0.05).Within the 3mm range of mucular:the difference of GCL-IPL thicknesses between NDR group and Normal group in any quadrant were not significant(all P>0.05).However,the average and each quadrant GCL-IPL thicknesses of the NPDR were thinner than Normal groups(P<0.05).the superior GCL-IPL thickness of NPDR group was thinner than NDR group(P<0.05).For the 6mm range:the superior thicknesses of NDR group were thinner than Normal group,The duration of diabetes of NPDR group was longer than NDR group(P<0.05).The level of glycosylated hemoglobin(HbA1c)of NPDR group was higher than NDR group(P<0.05).The thickness of superior RNFL in the optic disc was positively correlated with HbA1c(r=0.200,P=0.044),and negatively correlated with HDL(r=0.200,P=0.044).The average,inferior and nasal GCL-IPL thickness were significantly and negatively correlated with TC in the 3 mm range of the macula(r=?0.211,P=0.033;r=?0.224,P=0.023;r=?0.227,P=0.022).While the average thickness of GCL-IPL in the6-mm macular area was positively correlated with duration of diabetes(r=0.196,P=0.048).ConclusionFor diabetic patients,before microvascular changes occurs,their superior,nasal and average RNFL thickness in the optic disc become thinner than healthy people.RNFL thickness in the optic disc of the mild to moderate NPDR also becomes thinner.The each quadrant and average macular GCL-IPL thickness in both NDR and mild to moderate NPDR groups were thinner than normal group in 3mm range,The superior macular GCL-IPL thickness in both NDR and mild to moderate NPDR groups were thinner than normal group in 6mm range.The superior RNFL thickness in diabetic was positively correlated with HbA1c and negatively correlated with high-density lipoprotein.There was negative correlation between inferior,temporal and average GCL-IPL(3mm range)and total cholesterol in the diabetic.This study shows that the specific disorder of lipid metabolism in diabetic patients is correlated with the RNFL and GCL-IPL thickness,and may be involved in the pathogenic process.