图形视觉诱发电位鉴别伪盲的临床应用研究

目的　用图形视觉诱发电位（ｐａｔｔｅｒｎｖｉｓｕａｌｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ，Ｐ-ＶＥＰ）来评价客观视力以及用来鉴别伪盲的临床应用价值。方法　取志愿受检者１５８例（１５８眼）患黄斑病变或视神经病变眼，其中６５眼为黄斑病变组（Ａ组），９３眼为视神经病变组（Ｂ组），通过多元回归分析Ｐ-ＶＥＰ波幅和潜伏期与最佳矫正视力的关系。由此得出最佳关系方程，进而得出１５８眼Ｐ-ＶＥＰ推算视力（ＰＶＥＰ-ＶＡ），以及５３只伪盲眼（包括２１眼黄斑病变及３２眼视神经病变）的ＰＶＥＰ-ＶＡ，最后用受试者工作特征曲线（ＲＯＣ曲线）得出可接受ＰＶＥＰ-ＶＡ及主观视力差值范围，从而鉴别伪盲。结果　在１５′视角黑白棋盘格刺激下引出的Ｐ-ＶＥＰ波形，该波形的Ｐ１００波幅（记录为Ａｍｐ１５′）与主观视力的相关性最好，Ａｍｐ１５′与主观视力显著相关（Ａ组:Ｐ＝０．０１６；Ｂ组:Ｐ＜０．０００１）。Ａｍｐ１５′的对数［ｌｏｇ（Ａｍｐ１５′）］与主观视力（ｌｏｇＭＡＲ）的回归方程为:Ａ组:ｙ＝１．８６７－１．１００ｘ，Ｐ＜０．０００１，Ｂ组:ｙ＝１．５０２－０．７９９ｘ，Ｐ＜０．０００１［ｘ为ｌｏｇ（Ａｍｐ１５′），ｙ为ｌｏｇＭＡＲ］。利用回归曲线和ＲＯＣ曲线可以得到Ａ组辨别伪盲的截断值为０．３９７２时，其诊断敏感性为７３．３％，特异性为６８．０％；Ｂ组辨别伪盲的截断值为０．４１５０，其诊断敏感性为９０．５％，特异性为６７．５％。结论　Ｐ-ＶＥＰ的Ａｍｐ１５′用来判断客观视力最有效，对于鉴别伪盲也很有意义。

Clinical investigation of P-VEP in identifying malingerer

Objective To validate the value of pattern visual evoked potentials ( P-VEP) in estimating the objective visual acuity ( VA) and identifying the malingerers. Methods The data from 158 consecutive patients (158 eyes) aged from 20 years t0 65 years were included. There were 65 eyes with macular diseases ( group A) and 93 eyes with optic nerve diseases ( group B). The relationship between the amplitudes,latencies of P-VEP and best corrected visual acuity was deduced by a regression analysis. The best-correlated mode of P-VEP was found,the relationships was determined,and then the pattern VEP-estimated VA ( PVEP-VA) of 158 eyes and 53 malingering eyes which including 21 eyes with macular diseases and 32 eyes with optic nerve diseases were calculated. And then the malingerers were identified by a receiver operating characteristic ( ROC) curve which determining a cutoff for acceptable variance between PVEP-VA and subjective VA.Results The amplitude of 15’checkerboard size (Amp15’) was better correlated with VA in every group. Significant correlation was found between Amp15’ and VA,where P = 0. 016 in group A and P < 0. 000 1 in group B. A logarithmic curve was better fitted the correlation in the regression analysis,where y = 1. 867 - 1. lOOx,P < 0. 000 1 in group A and y = 1. 502 - 0. 799x,P < 0. 000 1 in group B [ x:log ( Arup15’) ,y:logMAR ] . The best cutoff value in identifying malingerers was 0. 397 2 (logMAR) ,which the sensitivity was 73. 3% and specificity was 68. 0% in group A, and 0. 415 0 (logMAR) ,which the sensitivity was 90. 5% and specificity was 67. 5% in group B by using the relations and ROC curve. Conclusion Amp15’of P-VEP is confirmed as a clinically useful tool in the objective assessment of VA and mearungful in identifying malingerers in possible non-organic visual loss.