Chromatic pupillometry as an effective screening tool for heritable retinal disease in rhesus macaques

Abstract

Purpose : Inherited retinal diseases (IRD) are important causes of blindness in humans and animals. Non-human primates (NHP) are useful animal models for human retinal disease due to similar retinal morphology and function. Identification of spontaneous disease models in NHP colonies requires quick screening tools due to the laborious, expensive nature of individual examination. Chromatic pupillometry is a noninvasive method of identifying IRD in humans; however, standard protocols employ time-consuming dark adaptation. We used this tool to compare chromatic pupillary light reflex characteristics utilizing a shortened dark adaptation protocol as well as standard dark-adaptation in rhesus macaques with PDE6C associated achromatopsia to controls with normal retinal function.

Methods : This prospective study evaluated red-, blue-, and white-light chromatic pupillometry following a shortened 1-minute versus standard 20-minute dark adaptation in rhesus macaques with PDE6C associated achromatopsia and sex- and age-matched controls without IRD. Pupil latency, degree of pupil constriction, pupil constriction time, and average constriction velocity were measured and compared between groups.

Results : Nine rhesus macaques (7 females and 2 males) homozygous for the PDE6C mutation and nine age-, sex-matched normal controls were used in this study. Pupil constriction latency was significantly longer in achromats versus controls with red- and blue-light stimulation (P<0.05); but did not differ between groups with white-light stimulation (P=0.2). Degree of pupil constriction was significantly less in achromats compared to controls with red-, blue-, and white-light stimulation (P<0.0001). Pupil constriction time was significantly shorter in achromats versus controls with red- and white-light stimulation (P<0.05), but did not significantly differ between groups following blue-light stimulation (P=0.9). Pupil constriction velocity was significantly slower in achromats versus controls with red-, blue-, and white-light stimulation (P<0.001). Dark adaption time was only a significant factor for degree of pupil constriction (P=0.008) and pupil constriction time (P=0.02) following blue-light stimulation.

Conclusions : Chromatic pupillometry is an effective tool for screening NHPs for achromatopsia. A 1-minute dark adaptation protocol was sufficient to discern NHPs with and without achromatopsia.

This is a 2021 ARVO Annual Meeting abstract.