Glaucoma Screening Using Relative Afferent Pupillary Defect

Abstract

To assess the relative afferent pupillary defect (RAPD) by swinging flashlight as a potentially useful screening test for glaucomatous optic neuropathy. One hundred seven subjects prospectively recruited from a mixed population of glaucomatous and nonglaucomatous patients were examined for a RAPD by 1 individual masked with regard to disease presence. All subjects underwent a swinging flashlight test with, when necessary, the aid of neutral density filters, to determine whether or not a RAPD was present. A determination of glaucoma diagnosis, as well as classification of disease stage, was subsequently assessed based upon review of history and ophthalmic examination. This clinical information regarding glaucomatous disease was ascertained without knowledge of study RAPD status. The acquisition of such clinical information and performance of swinging flashlight testing for RAPD was conducted by different individuals with the latter being a nonophthalmologist. Statistical analysis demonstrated an odds ratio of 9.71 (95% CI, 3.72-25.40) for glaucomatous disease if a RAPD was present, with a sensitivity of 66.7% and a specificity of 82.9%. Subanalysis of patients who had not previously undergone cataract surgery revealed an odds ratio of 17.05 (95% CI, 4.73-61.44) for glaucomatous disease if a RAPD was present, with a sensitivity of 68.8% and a specificity of 88.6%. RAPD screening by a swinging flashlight test with neutral density filters was moderately sensitive and strongly specific for glaucoma. Sensitivity, specificity, and predictive value improved when patients who had previously undergone cataract surgery were removed from the analysis.