Prevalence and causes of unilateral vision impairment and unilateral blindness in Australia the national eye health survey

IMPORTANCE This study determines the prevalence of unilateral vision impairment (VI) and unilateral blindness to assist in policy formulation for eye health care services. OBJECTIVE To determine the prevalence and causes of unilateral VI and unilateral blindness in Australia. DESIGN, SETTING, AND PARTICIPANTS This cross-sectional population-based survey was conducted from March 2015 to April 2016 at 30 randomly selected sites across all strata of geographic remoteness in Australia. A total of 1738 indigenous Australians 40 years or older and 3098 nonindigenous Australians 50 years or older were included. MAIN OUTCOMES AND MEASURES The prevalence and causes of unilateral vision impairment and blindness, defined as presenting visual acuity worse than 6/12 and 6/60, respectively, in the worse eye, and 6/12 or better in the better eye. RESULTS Of the 1738 indigenous Australians, mean (SD) age was 55.0 (10.0) years, and 1024 participants (58.9%) were female. Among the 3098 nonindigenous Australians, mean (SD) age was 66.6 (9.7) years, and 1661 participants (53.6%) were female. The weighted prevalence of unilateral VI in indigenous Australians was 12.5% (95% CI, 11.0%-14.2%) and the prevalence of unilateral blindness was 2.4% (95% CI, 1.7%-3.3%), respectively. In nonindigenous Australians, the prevalence of unilateral VI was 14.6% (95% CI, 13.1%-16.3%) and unilateral blindness was found in 1.4% (95% CI, 1.0%-1.8%). The age-adjusted and sex-adjusted prevalence of unilateral vision loss was higher in indigenous Australians than nonindigenous Australians (VI: 18.7% vs 14.5%; P = .02; blindness: 2.9% vs 1.3%; P = .02). Risk factors for unilateral vision loss included older age (odds ratio [OR], 1.60 for each decade of age for indigenous Australians; 95% CI, 1.39-1.86; OR, 1.65 per decade for nonindigenous Australians; 95% CI, 1.38-1.96), very remote residence (OR, 1.65; 95% CI, 1.01-2.74) and self-reported diabetes (OR, 1.52; 95% CI, 1.12-2.07) for indigenous Australians, and having not undergone an eye examination in the past 2 years for nonindigenous Australians (OR, 1.54; 95% CI, 1.04-2.27). Uncorrected refractive error and cataract were leading causes of unilateral VI in both populations (70%-75%). Corneal pathology (16.7%) and cataract (13.9%) were leading causes of unilateral blindness in indigenous Australians, while amblyopia (18.8%), trauma (16.7%), and age-related macular degeneration (10.4%) were major causes of unilateral blindness in nonindigenous Australians. CONCLUSIONS AND RELEVANCE Unilateral vision loss is prevalent in indigenous and nonindigenous Australians; however, most cases are avoidable. As those with unilateral vision loss caused by cataract and posterior segment diseases may be at great risk of progressing to bilateral blindness, national blindness prevention programs may benefit from prioritizing examination and treatment of those with unilateral vision loss.