The Pupil Response to Large Regional Stimuli in Patients with Focal Visual Field Loss

Abstract

Objective: To develop and use an intraocular analysis of the focal pupil response to large-sized, regional stimuli as a means of detecting areas of visual field loss. Patients and methods: A total of 42 normal subjects and 14 patients were tested with automated threshold perimetry and infrared pupillometry using computer-controlled, large-sized light stimuli (arcuate and quadrant shaped) at 10 apostilb intensity. These novel stimuli were presented (0.2 second duration) to different regions of the visual field of each eye. Each stimulus sequence was repeated 6 times. Results: A regional pupil deficit was detected in 7 of 12 eyes of 14 patients with visual dysfunction. The regional pupil response correctly corresponded to the visual field in 93 of 156 (60%) regions tested in the 14 patients. Conclusion: Detection of regional pupil deficits using large-sized light stimuli generally underestimates the degree of visual dysfunction as compared to automated threshold perimetry. One reason may be that retinal ganglion cells subserving the afferent pupillomotor pathway have larger receptive fields and greater spatial summation properties compared with those subserving the cortical visual pathway.

KEYWORDS:

• pupil
• pupillometry
• pupil perimetry
• afferent pupillary defect