Chromatic multifocal pupillometer for objective diagnosis of neurodegeneration in the eye and the brain.

Abstract

Purpose : To evaluate the use of chromatic multifocal pupillometry (CMP) for objective diagnosis of neurodegeneration in the retina and brain.

Methods : A CMP device (Accutome, Inc.) was used to record pupillary responses to red and blue light presented at 76 different locations of a 30-degree visual field (VF). Maximal percentage of pupil constriction (PPC), maximal constriction velocity (MCV) and the latency of MCV (LMCV) were determined. In the eye study, 13 patients with retinal dystrophy, 5 patients with macular dystrophy and 27 aged-matched controls were included. Patient's CMP results were compared to subjective VF testing [Humphrey 24-2 VF (HFA-VF) or Dark Adapted Goldmann VF (DA-GVF)]. In the brain study, 12 cognitively normal, subjects (ages 60-74) were included and CMP results were associated with cognitive (Montreal Cognitive Assessment, MoCA) testing.

Results : In retinal dystrophy patients, test points in which the PPC was lower than 4 standard errors (SEs) away from the mean of controls correlated with VF areas that were abnormal by DA-GVF. The variability in LMCV between different test points in response to red light was significantly higher in patients (range: 0.16-0.47) than in controls (range: 0.02-0.16; p<0.0001) and indicated its usefulness as a diagnostic tool with high sensitivity and specificity (Mann–Whitney–Wilcoxon analysis, area under the curve = 0.97.) Patients with macular degeneration demonstrated reduced PPC and MCV, more than 2 SEs away from the mean of controls, in response to red light in the majority of central (16 degree) HFA-VF locations. In the brain study, low MoCA (<26) was associated with reduced PPC in response to red light in the nasal region compared to normal MoCA (≥26) (3.3% [SE=0.3] vs 10.1% [SE=0.8]; p=0.018). Subjects with MoCA<26 compared to MoCA ≥26 showed reduced PPC in response to blue light in all regions except the inferior (nasal 5.8% vs 15.1% p=0.032; temporal 4.6% vs 13.9% p=0.028; superior 4.8% vs 13.8% p=0.033).

Conclusions : This study demonstrated the feasibility of using the CMP for identification of defects in visual pathways in different locations of the retina associated with VF defects and cognitive impairment. Different parameters of pupil response to chromatic multifocal stimuli may clarify the pathophysiology of different neurodegeneration diseases.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.