Correlation between inter-eye difference in average retinal nerve fiber layer thickness and afferent pupillary response as measured by an automated pupillometer in glaucoma

Purpose: To assess the correlations between the relative afferent pupillary defect measured by a binocular, computerized, and commercially available pupillometer and the inter-eye differences in average retinal nerve fiber layer (RNFL) thickness measured by spectral-domain optical coherence tomography (SD-OCT) and visual field index (VFI) and mean deviation (MD) measured by automated static perimetry in patients with glaucoma. Design: Cross-sectional study. Participants: Thirty four patients with open-angle glaucoma. Methods: Pupillary constriction amplitudes were measured with an automated pupillometer. SD-OCT imaging of the circumpapillary RNFL and automated static perimetry were performed within 6 months of pupillometry. Main Outcome Measures: Main outcome measures included Spearman correlation coefficients between relative afferent pupillary defect as measured by pupillometry and inter-eye differences in average RNFL thickness, VFI, and MD. Results: Correlation coefficients between relative afferent pupillary defect and inter-eye difference in average RNFL thickness, MD, and VFI were -0.81 (P<0.001), -0.73 (P<0.001), and -0.68 (P<0.001), respectively. Conclusions: The automated pupillometer quantifies asymmetry in afferent pupillary responses in proportion to structural and functional asymmetry as measured SD-OCT and automated static perimetry.