Researchers identified a contrast sensitivity threshold that may mark the point at which older US adults begin experiencing self-reported functional visual disability.

In a longitudinal cohort study, the researchers analyzed data from 4,475 community-dwelling Medicare beneficiaries aged 65 years and older who participated in the 2022 and 2023 National Health and Aging Trends Study. They measured binocular contrast sensitivity using a tablet-based assessment and evaluated self-reported visual disability, defined as difficulty recognizing familiar faces, reading newspaper print, or seeing a television across a room. The researchers sought to identify a clinically meaningful contrast sensitivity threshold associated with self-reported visual disability, while a secondary analysis examined whether baseline contrast sensitivity was associated with incident visual disability over 1 year.

The researchers identified 1.60 logarithm-scaled, binocular-presenting contrast sensitivity (logCS) as the threshold that best distinguished patients with and without self-reported visual disability. Those with visual disability at baseline had lower mean contrast sensitivity compared with those without visual disability, and patients who developed new visual disability during follow-up also experienced declines in contrast sensitivity.

Among the patients without visual disability at baseline, every 0.1-unit decrease in baseline logCS was associated with 12% higher odds of developing incident self-reported visual disability during the following year. The researchers noted that the proposed threshold demonstrated moderate sensitivity and specificity and was intended to provide a functionally meaningful benchmark rather than serve as a diagnostic cutoff.

The researchers acknowledged several limitations. Contrast sensitivity was measured at only two time points, limiting the assessment of long-term changes. Self-reported visual disability is subjective, detailed ocular diagnoses and refractive data were unavailable, and the study population consisted primarily of community-dwelling older US adults with generally preserved vision, which may limit generalizability. The researchers noted that the threshold requires validation in broader clinical and demographic populations.

In an invited commentary, Noemi Lois, MD, PhD, of the Wellcome-Wolfson Institute for Experimental Medicine and the Belfast Health and Social Care Trust in Northern Ireland, said identifying clinically meaningful thresholds is important but emphasized that the proposed cutoff should be replicated in other populations. She also noted that patients and the public should play an active role in defining clinically meaningful thresholds and minimal important differences for vision outcomes.

"The identified threshold should not be interpreted as a 'diagnostic cutoff' for SRVD. Rather, the purpose of this analysis was to establish a functionally anchored benchmark at which CS begins to correspond with meaningful patient-perceived visual difficulty," wrote lead study author Shu Xu, PhD, of the University of Michigan Institute for Social Research, and colleagues.

Senior study author Lindsey B. De Lott, MD, MS, reported consulting fees from argenx and honoraria from the American Academy of Neurology outside the submitted work. No other disclosures were reported by the study or invited commentary authors.

Source: JAMA Ophthalmology, Editorial