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Alice Lynne Williams, Xuanchu Duan, Priyanka Gogte, Michael Waisbourd, Lisa A Hark, George L Spaeth; A Novel Testing Sequence for RAPDx Pupillography. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1036.
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© ARVO (1962-2015); The Authors (2016-present)
The presence of a relative afferent pupillary defect (RAPD), traditionally detected with the swinging flashlight method, is a sign of optic nerve pathology but is often subjective. An objective tool that identifies and quantifies the degree of an RAPD could be useful in identifying and staging patients with glaucoma. The purpose of this study is to compare the standard testing sequence on the RAPDx pupillograph (Konan Medical USA, Irvine, CA) to a customized sequence. This novel sequence evokes a pupil response curve which more closely resembles that produced by the swinging flashlight method and allows for the measurement of a novel pupillary response parameter, the duration of maximum constriction (MC).
Forty-eight (48) patients with glaucoma underwent Humphrey visual field testing and RAPDx pupillography using a standard sequence and a custom sequence. Exclusion criteria included active inflammation of the eye, recent intraocular procedure, and any non-glaucomatous condition that may cause an RAPD, anisocoria or corectopia. RAPDx testing results included the response amplitude asymmetry (RAA), response latency asymmetry (RLA), and MC. These parameters were correlated with the visual field mean deviation (MD). Two-tailed p-values of Pearson correlation coefficients were calculated to determine the significance of these correlations.
Disease severity, as measured by average MD between the fellow eyes, was significantly correlated with higher RAA values (r= -0.3, p=0.04 for the standard sequence and r= -0.3, p=0.04 for the custom sequence). Average MD was also significantly correlated with higher RLA values for the custom sequence (r= -0.36, p=0.02) but not the standard sequence (r= -0.18, p=0.20). Correlations between average MD values and the novel pupillary response parameter, MC, failed to reach significance.
RAA and RLA, quantitative measures of asymmetric pupillary response between the two eyes, correlate with disease severity as measured by visual field MD in a group of patients with glaucoma. The custom testing sequence produces RLA values that correlate more closely to disease severity than those produced by the standard testing sequence. Further research is needed to determine the most useful testing sequences and combinations of clinical and pupillary response parameters for detecting and staging glaucoma.
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