糖尿病患者视网膜神经纤维层厚度的测定及相关因素分析

Measurement of retinal nerve fibre layer thickness and related factors in patients with diabetics

目的用GDx神经纤维分析仪(GDxVCC)测定眼底表现正常的2型糖尿病患者双眼视网膜神经纤维层(RNFL),了解有无早期RNFL变薄,分析危险因素与RNFL厚度的相关性。方法收集42例2型糖尿病患者相关病例资料。眼科常规检查后,用GDxVCC仪强化角膜补偿(ECC)和可变角膜补偿(VCC)测定双眼颞侧、上方、鼻侧、下方、颞侧曲线平均(TSNIT平均)、上方平均、下方平均、TSNIT标准差和神经纤维指数(NFI)5项值。分析糖尿病组的ECC、VCC5项检测值在诊断能力上的差异,即受试工作者曲线下面积(ROC);糖尿病组5项检测值的最大值、最小值和均数;血糖水平与糖尿病组检测值的相关性;糖尿病组中ECC与VCC5项检测值的差异比较;糖尿病组与对照组5个检测指标的差异;建立年龄与NFI值的线性回归方程。结果NFI值的ROC最大;ECC和VCC的NFI值均约为20;血糖与RNFL延迟量间无明显相关性。糖尿病组ECC与VCC5项指标的NFI值的差异无统计学意义(t=1.787,P=0.072);年龄对糖尿病患者NFI值的影响远远大于其对正常人NFI值的影响。结论NFI值为反映RNFL厚度的主要参考指标,年龄对糖尿病患者RNFL厚度存在较大影响;眼底表现正常的糖尿病患者存在早期RNFL变薄;ECC和VCC模式检测的NFI值无明显差异。糖尿病组2个测量模式间TSNIT标准差差异有统计学意义。

Objective GDx is scanning laser polarimetry. It can quamtitatively evaluate retinal nerve fibre layer （RNFL） thickness. The aim of this study was to detect RNFL thickness in the patients with type 2 diabetics mellitus and explore relevant risk factors. Methods A case-control study was performed. In this study, 42 patients with type 2 diabetics mellitus were enrolled with the mean age 60 ± 7.3. No the evidence of diabetic retinopathy was seen in all the patients upon the fundus fluorescine angiography. Ninety eyes from 45 normal subjects with matched-age were as controls. The demography of each patient was collected including age, disease course and disease severity. GDxVCC Nerve Fiber Analyzer with variable corneal compensation （VCC） mode and enhanced corneal compensation （ECC） mode was used for the RNFL scanning. GDx parameters included temporal-superior-nasal-inferior-temporal average （TSNITave）, superior average, inferior average, TSNIT standard deviation,and nerve fiber indicator （NFI） were compared between ECC mode and VCC mode. Area under receiver operating characteristic （ROC） was calculated. The relationship between age and NFI was evaluated by logistic linear regression analysis. This trail was assessed and approved by Ethics Committee of Eye ＆ ENT Hospital, and written information consent form was obtained before initial of the trial. Results In the five GDx parameters,the area under ROC of NFI was the biggest one. A significant difference was seen in TSNITstdDev value between ECC and VCC in diabetes group（27.21 ± 3.79 versus 22.61 ± 11.81 ,t = 2. 254,P = 0. 006）. NFI values tested by ECC mode and VCC mode were not significantly different（ 23.73 ± 13.05 versus 20. 28 ± 15.35 ,t = 1. 787,P =0. 072）. According to the linear regression equation,age showed more obvious influence on NFI of diabetic patients in ECC mode and VCC mode （ bECC = 0. 950, P = 0. 001, bVCC = 0. 690, P = 0. 006 ） in comparison with normal controls. Conclusion NFI is the main index reflecting the RNFL thickness. Age has important influence on NFI of diabetic patients. Those diabetic patients with ocular fundus seem to be normal have actually thinning RNFL. There is no significant difference between NFI tested in ECC and VCC modes, but TSNITstdDev obtained by ECC and VCC modes is different in diabetes mellitus.