Retinal nerve fiber layer thickness analysis in suspected malingerers with optic disc temporal pallor

PURPOSE: To investigate the value of temporal retinal nerve fiber layer (RNFL(temporal)) thickness in the prediction of malingering. MATERIALS AND METHODS: This prospective, cross-sectional study was conducted on 33 military conscripts with optic disc temporal pallor (ODTP) and 33 age-and sex-matched healthy controls. Initial visual acuity (VA(i)) and visual acuity after simulation examination techniques (VA(aset)) were assessed. The subjects whose VA(aset) were two or more lines higher than VA(i) were determined as malingerers. Thickness of the peripapillary RNFL was determined with OCT (Stratus OCT™, Carl Zeiss Meditec, Inc.). RNFL(temporal) thickness of the subjects were categorized into one of the 1+ to 4+ groups according to 50% confidence interval (CI), 25% CI and 5% CI values which were assessed in the control group. The VAs were converted to LogMAR-VAs for statistical comparisons. RESULTS: A significant difference was found only in the temporal quadrant of RNFL thickness in subjects with ODTP (P=0.002). Mean LogMAR-VA increased significantly after SETs (P<0.001). Sensitivity, specificity, positive and negative predictive values of categorized RNFL(temporal) thickness in diagnosing malingering were 84.6%, 75.0%, 68.8%, 88.2%, respectively. ROC curve showed that RNFL(temporal) thickness of 67.5 μm is a significant cut-off point in determining malingering (P=0.001, area under the curve:0.862). The correlations between LogMAR-VAs and RNFL(temporal) thicknesses were significant; the correlation coefficient for LogMAR-VA(i) was lower than the correlation for LogMAR-VA(aset) (r=−0.447, P=0.009 for LogMAR-VA(i); r=−0.676, P<0.001 for LogMAR-VA(aset)). CONCLUSIONS: RNFL(temporal) thickness assessment may be a valuable tool in determining malingering in subjects with ODTP objectively.