Abstract
Purpose: :
The pupillary light response is mediated by retinal rod and cone photoreceptors, as well as the recently identified melanopsin-expressing photoreceptive retinal ganglion cells (pRGCs). pRGCs are maximally sensitive to short wavelength light, the transmission of which is reduced by cataract. Here we investigate the effects of cataract surgery on the pupillary light response.
Methods: :
Patients undergoing cataract surgery and intraocular lens implantation with an ultraviolet-only blocking lens implant (Acrysof, Alcon Laboratoreis, Inc.) had pupillometry measurements taken prior to and 2-4 weeks after surgery. The pupil of the operated eye was dilated with g.tropicamide 1%, and following dark adaptation a white light stimulus of 4 lux was provided to that eye. Measurements of the consensual response were taken with a P3000 pupillometer (Procyon). An infrared camera recorded the response at 25fps, which was then analyzed using PupilFit software (Procyon) looking at both pupil area and dynamics. Paired t-tests were carried out comparing the responses before and after surgery.
Results: :
In this ongoing study, 6 patients have been screened to date (4 female and 2 male), with a mean age of 77 years (range 70-86). All 6 patients showed an increased pupil constriction following surgery as measured by pupil area following 10s of light exposure (p=0.0051). There was also a change in pupil dynamics with the postoperative measurements showing a more sustained constriction.
Conclusions: :
The change in maximal pupil constriction following cataract surgery is consistent with an increase in light transmission into the eye following removal of the cataract. The observed changes in sustained pupillary constriction may be attributed to increased pRGC stimulation due to an increase in short wavelength light transmission, as would be expected following cataract removal. This data suggest that pupillometry may provide a useful assay to study ocular function following surgical intervention.
Keywords: cataract • pupillary reflex • photoreceptors