Pattern visual evoked potentials for identifying malingering.

Objective: To investigate the efficacy of pattern visual evoked potentials (VEPs) in evaluating objective visual acuity (VA) and discriminating malingerers.

Methods: Two hundred and forty-nine eyes of 249 patients aged 20-65 years were included. There were 147 eyes with macular diseases (group 1) and 102 eyes with optic nerve diseases (group 2). Amplitudes and latencies were analyzed and correlated with best-corrected visual acuity by a regression analysis. We found the best-correlated mode of pattern VEP, determined the relations, and then calculated the pattern VEP-estimated VA (PVEP-VA) of all 249 eyes, another 30 malingering eyes, 13 eyes with macular diseases, and 17 eyes with optic nerve diseases, and used a receiver operating characteristic (ROC) curve to determine a cutoff for acceptable variance between PVEP-VA and subjective VA to discriminate malingerers.

Results: The best correlation was between the amplitude of 50' checkerboard size (Amp50') and VA in every group. Significant correlation was between Amp50' and VA, where p < 0.0001 in group 1 and p = 0.020 in group 2. A logarithmic curve best fitted the correlation in the regression analysis, where y = 1.731 - 1.569x (R(2) = 0.611, p < 0.0001) in group 1 and y = 2.413 - 2.169x (R(2) = 0.531, p < 0.0001) in group 2 [x: log(Amp50'), y: PVEP-VA (logMAR)]. By using the relations and ROC curve, we determined a variance value of 0.4041 (logMAR) with 100% sensitivity and 94.0% specificity in group 1 and 0.3658 with 70.6% sensitivity and 50.5% specificity in group 2 to discriminate malingerers.

Conclusions: The pattern VEP amplitude of 50' checkerboard size was useful to assess VA and can be helpful in discriminating malingering from real disability.