Abstract
Purpose: :
To study the sensitivity and specificity with which a commercially available pupillometer (Procyon P3000) can differentiate patients with primary open angle glaucoma from normal subjects based on relative afferent pupillary defect (RAPD).
Methods: :
Fifty normal subjects and thirty three glaucoma patients receiving treatment were enrolled. Pupillary light reflexes were elicited at three light intensities (7 lux, 0.7 lux, 0.07 lux). The data from direct pupillary responses were processed to obtain a measure of RAPDDIR and consensual responses to obtain RAPDCONS in decibels (dB). Combination of RAPDDIR and RAPDCONS at each light level were used to determine if the patient had a clinically significant RAPD based on predetermined cut-off values. The diagnosis of glaucoma was determined clinically, independently from the RAPD measured with the pupillometer.
Results: :
Sensitivity of 94% (95% CI, 79.8% to 99.3%) and specificity of 82% (95% CI, 68.6% to 91.4%) were achieved when the optimal cut-off values of 0.09dB and 0.12dB were used for RAPDDIR and RAPDCONS. In this group of patients, one patient with very mild glaucoma and a second with moderate but very symmetrical glaucoma had false negative results.
Conclusions: :
The RAPD elicited by the pupillometer can categorise a subject as normal or as having primary open angle glaucoma with high sensitivity and specificity. The method is objective, and quickly and easily administered. Although this pilot study has produced encouraging results, more subjects are required to confirm the usefulness of these settings.
Keywords: pupillary reflex • neuro-ophthalmology: optic nerve