Prevalence and determinants of visual impairment in Canada: cross-sectional data from the Canadian Longitudinal Study on Aging
The objective of this study is to determine the prevalence and determinants of visual impairment in Canada.
The design of the study was a Cross-sectional population-based study with 30,097 people in the Comprehensive Cohort of the Canadian Longitudinal Study on Aging.
Inclusion criteria included being between the ages of 45 and 85 years old, community-dwelling, and living near one of the 11 data collection sites across 7 Canadian provinces. People were excluded if they were in an institution, living on a First Nations reserve, were a full-time member of the Canadian Armed Forces, did not speak French or English, or had cognitive impairment.
Visual acuity was measured using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart while participants wore their usual prescription for distance, if any. Visual impairment was defined as presenting binocular acuity worse than 20/40.
Of Canadian adults, 5.7% (95% CI 5.4–6.0) had visual impairment. A wide variation in the provincial prevalence of visual impairment was observed ranging from a low of 2.4% (95% CI 2.0–3.0) in Manitoba to a high of 10.9% (95% CI 9.6–12.2) in Newfoundland and Labrador.
Factors associated with a higher odds of visual impairment included older age (odds ratio [OR] = 1.07, 95% CI 1.06–1.08), lower income (OR = 2.07 for those earning less than $20 000 per year, 95% CI 1.65–2.59), current smoking (OR = 1.52, 95% CI 1.25–1.85), type 2 diabetes (OR = 1.20, 95% CI 1.03–1.41), and memory problems (OR = 1.44, 95% CI 1.04–2.01).
Refractive error was the leading cause of visual impairment. Older age, lower income, province, smoking, diabetes, and memory problems were associated with visual impairment.