无视网膜病变的糖尿病患者对比敏感度检测分析

Characters of contrmt sensitivity in diabetic patients without diabetic retinopathy

目的探讨无视网膜病变的糖尿病患者对比敏感度（contrast sensitivity，CS）的变化。方法病例对照研究。严格选择52例（89只眼）已确诊的2型糖尿病患者和47例（68只眼）健康人作为受试对象。患者组为眼底无可见的视网膜病变且最佳矫正视力在1．0以上者。采用OPTEC6500型对比敏感度测试仪分别测定受检者1．5、3．0、6．0、12．0、18．0周／度（cycle／degree，c／d）5个空间频率的远、近距离CS值。观察糖尿病组与对照组之间CS值的差异，分析糖尿病组患者性别、年龄、糖尿病的病程及胰岛素使用时间对CS值的影响。组间相同频率及组内远、近距离CS值比较采用t检验或“检验，患者性别、病程、年龄及胰岛素使用时间与CS值的单因素相关分析采用简单直线相关分析法。结果对照组和糖尿病组远距离CS峰值分别为112．67±43．97和85．85±41．83，近距离CS峰值分别为83．68±35．91和55．20±24．14；两组远、近距离Cs峰值均出现于6．0c／d频率。对照组和糖尿病组远距离cs低值分别为26．19±17．69和12．69-4-7．09，近距离Cs峰值分别为18．68±11．81和8．22±5．68；两组远、近距离CS低值均出现在18．0c／d频率。糖尿病组远、近距离5个空间频率间的CS值差异有统计学意义（空间频率由低至高，远距离5个频率：t=3．11，3．38，2．77，3．48，3．86；P〈0．05。近距离5个频率：u=3．70，3．22；t’=3．69，3．88，4．25；P〈0．05）。糖尿病组在远、近距离的高、中、低频率及全频率CS值的异常率均显著高于对照组，两组差异有统计学意义（近距离4个频率：x2=11．86，8．17，9．14，5．81；P〈0．05。远距离4个频率：x2=13．27，6．70，4．01，4．50；P〈0．05）。糖尿病组患者性别与近距离3．0和6．0c／d低、中频率相关（r=0．26，0．28；P〈0．05），患者年龄与近距离12．0和18．0c／d高频率相关（r=-0．45，-0．28；P〈0．05）。糖尿病组患者的病程与近距离的2个高频率显著相关（r=-0．25，-0．39；P〈0．05），与远距离的4个中、高频率相关（r=-0．26，-0．28，-0．30，-0．34；P〈0．05）。糖尿病组患者胰岛素使用时间与远距离的2个高频率相关（r=-0．30，-0．31；P〈0．05）。结论对比敏感度检测指标对提示糖尿病患者早期视功能改变有一定意义。远距离的高频段CS值是糖尿病患者早期视功能损害的敏感指标之一。患者视网膜功能的改变最终与糖尿病的病程相关，病程是糖尿病患者早期cs值异常下降的最危险因素之一。

Objective To explore the change of contrast sensitivity （CS） in diabetic patients without diabetic retinopathy. Methods It was a case-control study. We screened and tested 52 type 2 diabetic patients （89 eyes） and 47 healthy persons （68 eyes）. OPTEC 6500 contrast sensitivity tester was used to examine near and distance CS values on 1.5, 3.0, 6.0, 12.0, 18.0 cycles/degree （c/d） respectively. We kept strict inclusion criteria on subjects, no retinopathy was found and best corrected vision acuity was above 1.0. The difference of CS values between these two groups was investigated, and the influence of gender, age, duration of diabetic mellitus and application time of insulin on CS values, respectively. T-test or u-test was used to compare the means of CS values between these two groups, near and distance CS values in each group. Simple linear correlation and multiple regression analysis were used to analyze the single factor and multiple factors correlation between CS values and age, duration, gender, and application time of insulin, respectively. Results The maximum CS values in both distance and near were 112.67 ±43.97, 85.85 ±41.83 and 83.68 ±35.91, 55.2±24.14, both appeared in 6.0 c/d. The minimum CS values in both distance and near were 26. 19± 17.69, 12. 69 ±7.09 and 18.68± 11.81, 8.22±5.68 ,respectively, both appeared in 18.0 c/d. Distance and near C$ values in diabetic group and control group had very significant differences at these five spatial frequencies （From 1.5 to 18.0 c/d, the test values on distance, t = 3.11, 3.38, 2. 77, 3.48, 3.86 ;P 〈 0. 05 ; the test values on near, u = 3.70, 3.22 ;t＇ = 3.69, 3.88, 4. 25 ; P 〈 0. 05 ）. Abnormal rate in diabetic group on high, medium, low and all frequencies were higher than control group, regardless of distance or near CS values （ in near X2 = 11.86, 8.17, 9. 14, 5.81 ;P 〈0. 05 ; on 4 combinations in distance X2 = 13.27, 6. 70, 4. 01,4. 50;P 〈0. 05）. In diabetic group, gender related with 3.0 and 6. 0 e/d CS values on near-distance （ r = 0. 26, 0. 28 ; P 〈 0. 05） ; age related with high-frequencies on near （ r = - 0.45, - 0. 28 ; P 〈 0. 05 ） ; duration of diabetic mellitus related with high-frequencies on near（ r = - 0. 25, - 0. 39 ; P 〈 0. 05 ） , and related with medium, high frequencies on distance （ r = - 0. 26, - 0. 28, - 0. 30, - 0. 34 ; P 〈 0. 05 ） ; application time of insulin related with high-frequencies on distance （ r = - 0. 30, - 0. 31 ; P 〈 0. 05 ）. Conclusions There exists important sense of CS value on showing visual function changes accurately in early-stage of diabetes mellitus. The high frequencies on distance is the sensitive index in vision impairment. Duration of diabetes closely relates with changes of retinal function ultimately, can be classified as the most important risk factor of CS values decline in early-stage diabetic patients.