糖耐量异常及2型糖尿病患者早期视网膜损伤的观察

Study of early retinal damage in patients with impaired glucose tolerance and type 2 diabetes mellitus

目的 观察糖耐量异常（IGT）人群和已确诊2型糖尿病（DM）尚未进展至糖尿病视网膜病变（DR）人群的视觉功能的异常及视网膜神经纤维层（RNFL）厚度的变化,探讨糖代谢异常造成的视网膜损伤.方法 横断面研究.随机选取2012年6月至2013年6月间于沧州市中心医院就诊的有2型DM病史10～15年但尚未进展至DR的患者76例为2型DM组,同期、同院就诊的IGT病史3年以上尚未进展至DM的患者79例为IGT组,随机选取同龄健康体检者80例为对照组.所有受检者进行OCT、视觉对比敏感度（CS）、视力、眼底镜等检测,2型DM患者进行FFA检查.以上受检者均取左眼的OCT和CS测量值计入统计结果.采用方差分析的方法,比较2型DM组和IGT组的视盘周围RNFL厚度与对照组的差异,分不同的年龄段比较2型DM组、IGT组与对照组CS检测值的差异,并采用相关分析分析RNFL厚度和CS检测值的相关性.结果 2型DM组RNFL的厚度值全周为（98.3±10.3） μm、视盘上方象限（114.8±14.7） μm、下方象限（128.5±15.4）μm和鼻侧（71.4±8.6） μm,明显低于对照组（P＜0.05）,IGT组的RNFL的厚度与对照组比较无明显差异.2型DM组的CS检测值与对照组比较,40岁～年龄段在6、12、18 c/d频段有明显差异（P＜0.01）,50岁～年龄段和60～70岁年龄段在3、6、12、18 c/d频段有明显差异（P＜0.05）,IGT组40岁～年龄段在12、18 c/d频段有明显差异（P＜0.05）,50岁～年龄段在6、12、18 c/d频段有明显差异（P＜0.05）,60～70岁年龄段在6、12 c/d频段有明显差异（P＜0.05）.CS在6 c/d频段的检测值与RNFL平均厚度相关性分析显示两者呈正相关（r=0.596,P＜0.01）.结论 2型DM患者在视网膜尚未出现可视的微血管病变以前,已经存在RNFL变薄和CS代表的部分视功能的减低;CS等视功能的减低的出现可能早于RNFL变薄.

Objective To evaluate the effect of early damage to the retina caused by impaired glucose tolerance （IGT） by studying the changes in visual function and the retinal nerve fiber layer （RNFL）.Methods This was a cross-sectional study.Patients who visited Cangzhou Center Hospital from June 2012 to 2013 were randomly selected to be assigned to 3 groups：the diabetes mellitus （DM） group （76 patients with type 2 diabetes mellitus for 10 to 20 years without diabetic retinopathy）,the IGT group （79 patients with IGT for 3 or more years who have not yet progressed to DM） and a normal control group （80 healthy people）.All groups underwent optical coherence tomography （OCT）,contrast sensitivity （CS）,visual acuity tests,and ophthalmoscope examination.In the DM group,patients were further checked by FFA.Differences in these results,including RNFL thickness of the optic disk and CS measurements,were statistically compared between the different groups （one-way ANOVA）.In addition,the correlation of RNFL thickness and CS measurements were analyzed.Results The RNFL thicknesses of patients in the DM group were much lower than in the normal controls in an average 360＆#176; circumference （98.3±10.3,P〈0.01）,in the quadrant above the optic disk （114.8±14.7,P〈0.01）,beneath the optic disk （128.5±15.4,P〈0.01） and in the nasal quadrant （71.4±8.6,P〈0.05）.No significant difference was found between the IGT group and normal control group.At the same time,there was a significant difference in CS measurements between the DM group and normal controls,including patients in their 40s at 6 c/d,12 c/d and 18 c/d （P〈0.01）,in their 50s at 3 c/d,6 c/d,12 c/d and 18 c/d （P〈0.05）,and in their 60s and 70s at 3 c/d,6 c/d,12 c/d,and 18 c/d （P〈0.05）.Obvious differences were found in the IGT group for patients in their 40s at 12 c/d and 18 c/d （P〈0.05）,in their 50s at 6 c/d,12 c/d and 18 c/d （P〈0.05） and in their 60s and 70s at 6 c/d and 12 c/d （P〈0.05）.There was also a positive correlation between CS measurements at the intermediate frequency （6 c/d） and the average RNFL thickness （r=0.596,P〈0.01）.Conclusion Results of the present study show that a thinner RNFL and visual dysfunction appear before significant microangiopathy in the retina of type 2 DM patients.Visual function decreases in steps in patients with IGT,and this occurs earlier than a thinning of the RNFL.