Age-Related Macular Degeneration and Visual and Physical Disability in a Nationally Representative Sample from the United States

Abstract

Purpose: Outline the association between age-related macular degeneration (AMD) and functional difficulty using novel item response theory (IRT) psychometric techniques, and highlight populations particularly at risk of functional impairment.

Methods: This cross-sectional study included 5604 US adults. Primary outcomes were item response theory-adjusted visual and physical difficulty scores. Secondary analyses of AMD populations at highest risk of reporting greater functional difficulty were undertaken.

Results: In total, there were 386 participants with early AMD (mean presenting visual acuity [pVA], 0.12) and 55 with late AMD (mean pVA, 0.35). Those with late AMD reported substantially higher item visual difficulty, whereas those with both early/late AMD reported significantly higher item physical difficulty versus those with no AMD (P < .05). In univariate regression, only those with late AMD reported significantly higher visual difficulty versus those with no AMD (10.1 points [95% confidence interval (CI), 8.2-12.1 points] vs 7.1 points [95% CI, 7.0-7.2 points]; P = .003). Both early/late AMD reported higher physical difficulty versus those with no AMD (11.6 points [95% CI, 11.1-12.1 points; P = .005]; 13.4 points [95% CI, 11.8-15.0 points; P = .03], respectively, versus 11.0 points [95% CI, 10.9-11.1 points]. After adjustment for sociodemographic and medical variables (excluding pVA), only those with late AMD reported significantly greater visual and physical difficulty versus those with no AMD (10.0 points [95% CI, 8.2-11.9 points] vs 7.1 [95% CI, 7.0-7.2 points; P = .002]; and 12.7 points [95% CI, 11.3-14.0 points] vs 11.0 [95% CI, 10.9-11.1 points; P = .02], respectively); greater visual difficulty in those with late AMD persisted after additionally adjusting for pVA versus those with no AMD (9.1 points [95% CI, 7.6-10.6 points] vs 7.1 points [95% CI, 7.0-7.2 points; P = .01]). Among individuals with AMD, lower income, higher medical comorbidities, depression, and pVA predicted greater visual and physical difficulties.

Conclusions: AMD confers significant functional difficulty among US adults with sociodemographic characteristics influencing dysfunction; highlighting the value of alternatives to Snellen visual acuity in assessing visual characteristics. With aging populations and the increasing prevalence of AMD, health care professionals should be aware of the functional burden of AMD and recognize those at higher risk of functional difficulty.

Translational relevance: Contemporary psychometric validation techniques can be effective in accurately describing the level of functional impairment for those with visual impairment.

Keywords: age-related macular degeneration; function; macular degeneration.