Chromatic pupilloperimetry for objective diagnosis and monitoring of optic neuritis

Abstract

Purpose : To characterize rod-, cone- and melanopsin-mediated pupil responses (PLR) for small focal chromatic light stimuli presented in peripheral and central retinal locations in optic neuritis patients.

Methods : Ten acute optic neuritis (ON) patients (mean age ± standard deviation: 32.3 ± 9.29 years) 7 females and 3 males, and 26 age-similar healthy controls (35.4 ± 12.4 years) 15 females and 11 males, were enrolled. The pupil light responses (PLR) for small (0.43°) red and blue light stimuli (peak 485 nm and 625 nm, respectively) presented at 54 locations of a 24-2 visual field were recorded. In addition, the melanopsin-mediated sustained pupil responses (pupil response, recovery, PRP) were evaluated at central and peripheral VF locations. All patients underwent Optical Coherence Tomography imaging, standard perimetry (Humphrey SITA Standard protocol), and their best corrected visual acuity was determined.

Results : Attenuated melanopsin-mediated PLR was recorded in the peripheral VF in ON eyes compared to controls, with ROC AUC = 91.1% (p=0.001). The rod and cone-mediated percentage of pupil contraction (PPC) were lower by more than 2 standard errors (SEs) from the mean of controls in the majority of visual field test targets (mean ± SE: 60% ± 12 % and 55% ± 10 %, respectively) in optic neuritis eyes, even in patients with normal visual acuity. Furthermore, even though normal visual acuity and VEP P100 were recorded in the fellow eyes, substantially lower rod- and cone-mediated PPC values (lower than 2SEs from the mean of controls) were identified in the fellow eyes of all patients (mean ± SE: 33% ± 9 % and 30%± 7 % of test targets, respectively). Peripapillary OCT of both eyes was within normal limits.

Conclusions : Substantially lower rod-, cone- and melanopsin-mediated PLR are recorded in ON and fellow eyes of patients, even in eyes with normal VA. The melanopsin-mediated pupil response to blue light at the peripheral retina may present a novel, highly sensitive surrogate functional biomarker for detection of ON.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.