Correlation Of Relative Afferent Pupillary Defect With Retinal Nerve Fiber Layer Thickness In Asymmetric Glaucoma

Abstract

Purpose: : The presence of a relative afferent pupillary defect (RAPD) is indicative of an asymmetric defect in anterior visual pathway. The aim of this study is to examine the correlation of the amount of retinal nerve fiber layer (RNFL) thickness reduction and the depth of a clinically detectable RAPD in patients with asymmetric glaucoma.

Methods: : Enrolled were 30 glaucoma patients with the RAPD more than 0.6 log unit. RAPD was quantified by placing log–scaled neutral density filters in 0.3 logarithmic step–wise fashion while performing the swinging flashlight test until the defect disappeared. The RNFL thickness around the optic disc was determined using Fast RNFL thickness (3.4) of optical coherence tomography 3000 with the average RNFL thickness program. Linear regression analysis was used in assessing the relationship between RAPD and the ratio of RNFL thickness in more affected eyes relative to that in less affected eyes.

Results: : Average of mean deviation was –20.61±7.75 dB in more affected eyes, whereas –3.42±5.37 dB in less affected eyes (p<0.0001). RAPD ranged from 0.6 to 2.4 log unit. The mean of average RNFL thickness was 51.51±14.46 in more affected eyes and 84.12±16.97 in less affected eyes, respectively (p<0.0001). There was a statistically significant correlation between RAPD and the RNFL thickness ratio (r=0.718, p<0.0001; Y = 0.847 – 0.18X).

Conclusions: : RAPD with 0.6 log unit was detectable when more than 24% retinal nerve fibers were reduced in more affected eyes compared with in less affected eyes.

Keywords: nerve fiber layer • pupillary reflex • ganglion cells