Comparative study of 3 techniques to detect a relative afferent pupillary defect

Abstract

Purpose: To compare the standard method of testing for a relative afferent pupillary defect (RAPD) using the Standard Swinging Flashlight Method (S-SFM) with 2 novel techniques, to evaluate the validity and reproducibility of each method, and to validate the clinical significance of detecting more subtle RAPDs by correlating the extent of glaucoma damage with the presence or absence of an RAPD as assessed by each method.

Patients and methods: In this prospective, observational study 101 consecutive patients (68 diagnosed glaucoma patients, 20 glaucoma suspects including ocular hypertensives, and 13 controls) were screened for the presence or absence of an RAPD using the S-SFM, Magnifier-Assisted Swinging Flashlight Method (MA-SFM), and Ophthalmoscopic Swinging Flashlight Method . Humphrey visual field mean deviation (MD) of each eye and the intereye differences in MD and Disc damage likelihood score (DDLS) and intereye difference in DDLS were calculated. Sensitivities for each method (S-SFM, MA-SFM, and Ophthalmoscopic Swinging Flashlight Method) were calculated at increasing levels of change in DDLS and MD. Weighted κ scores were calculated for agreement between tests.

Results: MA-SFM is the most sensitive method for determining an RAPD in terms of both intereye difference in DDLS and intereye differences in MD at all levels of change. Weighted κ scores revealed substantial agreement between tests for the same method, and moderate to substantial agreement among the observers.

Conclusions: This study confirms results of our earlier study suggesting that swinging flashlight test modified with magnification (MA-SFM) can provide a simple, inexpensive, reproducible method of detecting an RAPD.