Correlation Between Inter-Eye Difference in Average Retinal Nerve Fiber Layer Thickness and Afferent Pupillary Response as Measured by an Automated Pupillometer in Glaucoma

Abstract

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. Cross-sectional study. Thirty four patients with open-angle glaucoma. 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 included Spearman correlation coefficients between relative afferent pupillary defect as measured by pupillometry and inter-eye differences in average RNFL thickness, VFI, and MD. 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. The automated pupillometer quantifies asymmetry in afferent pupillary responses in proportion to structural and functional asymmetry as measured SD-OCT and automated static perimetry.