Visual acuity and contrast sensitivity at various stages of cognitive impairment in the COMPASS-ND study

Abstract

Purpose : Beyond changes related to normal aging, visual disturbances have been reported in individuals with Alzheimer’s disease (AD) and other neurological disorders, and have been proposed as possible complementary biomarkers for cognitive decline. Here we report preliminary visual findings from the COMPASS-ND study of the Canadian Consortium on Neurodegeneration in Aging (CCNA) in a diverse group of individuals at different stages of cognitive impairment, diagnosed via clinical consensus and stringent criteria.

Methods : We used data from 109 older adults (age 60 to 89, M= 72.94, SD= 7.01) that are part of the CCNA cohort with various clinically confirmed diagnoses (subjective cognitive impairment, SCI, n = 24; mild cognitive impairment, MCI, n = 64; mild AD, n = 21). Reading acuity (MNRead) and contrast sensitivity (Mars test) were tested with habitual correction. We additionally report scores on the Montreal Cognitive Assessment (MoCA) scale for our three groups.

Results : Twenty-five percent of participants had reduced reading acuity (> .5 logMAR [20/63]) and 23% presented with moderate to severe loss of contrast sensitivity (< 1.48 log CS [3.3% contrast]). Only 6.5% had combined reduced visual acuity and moderate to severe contrast sensitivity. Notably, only 8.3% of individuals with SCI presented with reduced acuity, compared to 32.3% and 23.8% of those with MCI and AD, respectively (χ² = 5.28 p = .071). Individuals with AD had significantly lower contrast sensitivity than those with MCI and SCI (p = .04, ω² = .04; Figure 1), after adjusting for age, sex and education. No differences in visual acuity were observed p = .46, ω² = .004.

Conclusions : Using a chart-based measure, the Mars test, we were able to replicate previous reports of declines in contrast sensitivity in individuals with AD relative to those with MCI and SCI. We also observed higher rates of reduced reading acuity in the AD and MCI groups relative to those reported the general population. These results set the groundwork for examining the relationship between vision status and cognitive function, brain integrity, quality of life, in these groups.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Figure 1. Unadjusted Contrast Sensitivity scores across participant groups