| Purpose:To measure the thickness of the retinal nerve fiber layer(RNFL)and retinal ganglion cell complex(GCC)in diabetic patients in preclinical stage and early stage with or without diabetic complications by optical coherence tomography(OCT).To analyze the correlation in patients with or without extra-ocular diabetic complications.To observe the correlation between retinal nerve layer thickness and visual field/pattern visual evoked potential(PVEP)changes in diabetic patients in preclinical stage and early stage,which may provide an effective method for early DR diagnosis.Methods:The study recruited 252 patients with type 2 diabetes as experimental group,who were divided into non-diabetic retinopathy(NDR)group,mild non-proliferative diabetic retinopathy(NPDR)group,diabetic kidney disease group,diabetic lower extremity arterial disease group,and diabetic neuropathy group according to the clinical diagnosis.The control group consisted of 34 ophthalmic inpatients who had no diabetics and other retina diseases.The following data was collected for each patient: medical history information,basic information,general ophthalmological examination,mean deviation(MD)and pattern standard deviation(PSD)of visual field,P100 latency and amplitude of pattern visual evoked potential(PVEP),the thickness of the peripapillary RNFL(pRNFL)and the thickness of macular GCC(m GCC).The differences in pRNFL layer and m GCC layer thickness were compared between patients with early DR and extra-ocular diabetic complications,as well as between the control group.The correlation between diabetic complications and pRNFL layer / m GCC layer thickness was analyzed.The difference in VF and PVEP were compared between groups if correlation existed in patients with diabetic complications.The correlation between pRNLF/m GCC thickness and VF/PVEP was analyzed to explore the relationship between retinal structural changes and functional changes in early DR.Statistical analysis was performed by SPSS 25.0 software,and significant differences were reported if P<0.05.Results:(1)There was no significant difference in sex,age,left or right eye and intraocular pressure(IOP)among the three groups(P>0.05).(2)There were significant differences in the thickness of nasal RNFL layer between NDR group and control group(P =0.032).The average,superior,inferior and nasal RNFL layer thickness of NPDR group were thinner than that of control group.The inferior thickness had the most significance(P <0.001).Compared with NDR group,the thickness of RNFL layer became thinner in A,S and I regions in NPDR group(P<0.05).(3)There were significant differences in the thickness of RNFL layer between the non-nephropathy group and the control group in S and N regions(P < 0.05).Between the nephropathy group and the control group,the thickness of RNFL layer were significantly thinner in A,S and N regions(P<0.05).There were significant differences in the thickness of RNFL layer between the non-nephropathy group and the nephropathy group in A,I and N regions(P<0.05).(4)There were significant differences in the thickness of RNFL layer between the non-angiopathy group and the control group in A,S and N regions(P<0.05).There were significant differences in the thickness of RNFL layer between the angiopathy group and the control group in A,S,I and N regions(P < 0.05).(5)There were significant differences in the thickness of RNFL layer between the non-neuropathy group and the control group in area A,S and N regions(P<0.05).Between the group with neuropathy and the control group,the thickness of RNFL layer were significantly thinner in S,I and N regions(P<0.05).(6)There were significant differences in the thickness of GCC layer in A and N regions between the NDR group and the control group(P<0.05).There were significant differences in the thickness of GCC layer in A,S,I and N regions between the NPDR group and the control group(P < 0.05).The thickness of GCC layer in area A,S and I regions in NPDR group was significantly thinner than that in NDR group(P<0.05).(7)Compared with the control group,the thickness of GCC layer in non-nephrotic group became thinner in A and N regions(P<0.05).Compared with the control group,the thickness of GCC in nephropathy group was thinner in area A,S and N(P<0.05).(8)There were significant differences in the thickness of GCC layer between the non-angiopathy group and the control group in area A and N(P<0.05).Compared with the control group,the thickness of GCC in area A,S and N in angiopathy group was significantly thinner(P < 0.05).(9)There were significant differences between the thickness of GCC layer between the non-neuropathy group and the control group in A,S,and N regions(P < 0.05).Compared with the control group,the thickness of GCC in neuropathy group were significantly thinner in A and N regions(P<0.05).(10)The thickness of RNFL layer around the optic disc was negatively correlated with DR in S and I regions.The thickness of GCC in macular area was negatively correlated with DR in S and I regions.(11)There were significant differences in MD between NDR group and control group in VF(P = 0.049).There were significant differences in MD,PSD and amplitude in NPDR group compared with control group(P<0.05).There were significant differences in MD and PSD between NPDR group and NDR group(P <0.01).The average defect value of visual field in control group,NDR group and NPDR group was aggravated gradually.There was localized visual field defect in NPDR group compared with control group and NDR group.(12)The MD of VF was positively correlated with nasal pRNFL thickness,superior,inferior and nasal m GCC thickness,while PSD was negatively correlated with inferior pRNFL thickness.The P100 latency of PVEP was negatively correlated with the upper m GCC thickness,and the P100 amplitude was positively correlated with the superior and nasal pRNFL thickness and the average nasal and temporal m GCC thickness,but there were no significant differences(P<0.05,r<0.6).Conclusion:The results indicated that retinal nerve fiber layer(pRNFL)thickness and macular ganglion cell layer(m GCC)thickness changes were associated with diabetic retinopathy(DR)and happened before clinical diagnosis.The changes in pRNFL and m GCC thickness were found to be specific to DR and not related to extra-ocular diabetic complications.The study also found that visual function impairment,including increased average visual field defect and decreased P100 amplitude of visual evoked potential,appeared in the early stages of DR.Finally,there maybe a slight correlation between the structural changes in pRNFL and m GCC layers and the changes in visual function detected by visual field and visual evoked potential. |
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