图形视觉诱发电位鉴别伪盲的临床应用研究

Clinical investigation of P-VEP in identifying malingerer

目的用图形视觉诱发电位(pattern visual evoked potential,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(PVEPVA),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(log MAR)的回归方程为:A组:y=1.867-1.100x,P<0.000 1,B组:y=1.502-0.799x,P<0.000 1[x为log(Amp15'),y为log MAR]。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0.397 2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0.415 0,其诊断敏感性为90.5%,特异性为67.5%。结论 PVEP的Amp15'用来判断客观视力最有效,对于鉴别伪盲也很有意义。

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 to 65 years were included. There were 55 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 cal- culated. 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 YA. 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. 857 - 1. 100x, P 〈 0.000 1 in group A andy=1.502-0. 799x,P〈0. 000 1 in group B [x：log（Amp15＇）,y： logMAR]. The best cutoff value in identifying malingerers was 0. 397 2（logMAR） ,which the sensitivity was 73.3% and specificity was 58.0% in group A, and 0. 415 0 （ log- MAR） ,which the sensitivity was 90.5% and specificity was 57.5% in group B by using the relations and ROC curve. Conclusion Amp15＇of P-VEP is confirmed as a clinical- ly useful tool in the objective assessment of VA and meaningful in identifying malinger- ers in possible non-organic visual loss.