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 (RNFLtemporal) 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 (VAi) and visual acuity after simulation examination techniques (VAaset) were assessed. The subjects whose VAaset were two or more lines higher than VAi were determined as malingerers. Thickness of the peripapillary RNFL was determined with OCT (Stratus OCT™, Carl Zeiss Meditec, Inc.). RNFLtemporal 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 RNFLtemporal thickness in diagnosing malingering were 84.6%, 75.0%, 68.8%, 88.2%, respectively. ROC curve showed that RNFLtemporal 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 RNFLtemporal thicknesses were significant; the correlation coefficient for LogMAR-VAi was lower than the correlation for LogMAR-VAaset (r=−0.447, P=0.009 for LogMAR-VAi; r=−0.676, P<0.001 for LogMAR-VAaset). Conclusions: RNFLtemporal thickness assessment may be a valuable tool in determining malingering in subjects with ODTP objectively.

Asymmetry Analysis of the Retinal Nerve Fiber Layer Thickness in Normal Eyes using Optical Coherence Tomography

PURPOSE: To investigate the asymmetry of the retinal nerve fiber layer thickness (RNFLT) with respect to the horizontal and vertical meridian and between the right and left eye in normal subjects. METHODS: The RNFLT was measured in 121 normal volunteers by optical coherence tomography (OCT). The RNFLT was analyzed by dividing the circle scanning area (diameter 3.4 mm) around the optic disc into 4 quadrants and 12 sectors. RESULTS: There was a significant difference between the RNFLT of the nasal and temporal quadrant in individual eyes. There was a significant difference between the RNFLT of corresponding sectors with respect to the vertical or horizontal meridian in individual eyes. The nasal and temporal RNFLTs were asymmetrical between the right and left eye in the quadrant and sector analysis. The RNFLT of the nasal and temporal quadrant was thicker in the right eye. The nasal and inferior RNFLT measured by OCT had a significant correlation with degree of refractive error. CONCLUSIONS: In normal subjects without significant anisometropia, there was significant asymmetry of the RNFLT for each eye as well as between the right and left eye.