Abstract
Purpose: :
To study the correlation between relative afferent pupillary defects (RAPD) and quantitative measures of functional and structural damage in glaucoma patients with unilateral visual field defects.
Methods: :
Twenty consecutive adult patients with a diagnosis of glaucoma and normal Humphrey visual field (HVF) in one eye and a repeatable glaucomatous visual field defect in the fellow eye were prospectively enrolled in this study. Subjects with ocular pathology likely to interfere with visual field testing or assessment of RAPD were excluded from the study. The RAPD was identified using the swinging flashlight test (SFT) method and was quantified with neutral-density filters. HVF indices of glaucoma damage [mean deviation (MD) and pattern standard deviation(PSD)], global measurements of retinal nerve fiber layer thickness on optical coherence tomography (OCT) and clinically assessed cup to disc ratio were recorded.
Results: :
Relative afferent pupillary defects were seen in 8 patients. Subjects with RAPD had a greater difference in HVF MD between the 2 eyes as compared to subjects without RAPD (15.13 ± 7.73 dB with RAPD vs. 4.66 ±2.23 dB without RAPD, p<0.01). The difference in HVF PSD between the 2 eyes was higher in the RAPD group as compared to subjects without RAPD (8.68 ± 3.00 dB with RAPD vs. 5.44 ± 3.06 dB without RAPD, p=0.03). The linear correlation between the difference in MD and PSD and the density of RAPD was statistically significant (R2 =0.73, p<0.001 for MD; R2=0.23, p=0.03 for PSD). The cup to disc asymmetry and inter eye difference in OCT measurements was not significantly different between the 2 groups.
Conclusions: :
RAPD density as measured clinically using SFT was found to correlate well with the difference in MD and PSD between the 2 eyes in asymmetric glaucomatous visual field defects. The findings support the potential use of clinical quantitative RAPD assessment as a surrogate for visual fields in glaucoma subjects unable to undergo formal visual field testing. A new onset RAPD may suggest glaucoma progression in such cases.
Keywords: visual fields • optic nerve • pupillary reflex