Age-Specific Causes of Bilateral Visual Impairment

OBJECTIVES: To describe the age-specific prevalence of common eye diseases causing bilateral visual impairment and estimate the total number of Australians with cause-specific visual impairment. METHODS: Cluster-stratified random sample of 5147 residents aged 40 years and older from urban and rural areas and aged-care facilities. Participants completed a standardized interview and eye examination. Four levels of bilateral visual impairment were defined: less than 20/40 to 20/60 and/or homonymous hemianopia (mild), less than 20/60 to 20/200 or better and/or less than 20 degrees to 10 degrees radius field (moderate), less than 20/200 to 10/200 and/or less than 10 degrees to 5 degrees radius field (severe), and less than 1O/ 200 and/or less than 50 radius field (profound). The major cause of vision loss was identified for all participants found to be visually impaired. RESULTS: Uncorrected refractive error was the most common cause of bilateral visual impairment across all decades of life, rising from 0.5% in 40- to 49-year-olds to 13% among those aged 80 years and older. Prevalence of visual impairment due to diabetic retinopathy was 0.7% in 50- to 59-year-olds and 0.8% in those older than 80 years. Visual impairment due to glaucoma had a prevalence of 0.7% among 60-year-olds and rose to 4% of those older than 90 years. The prevalence of visual impairment due to cataract (only present in those aged 70 years or older) rose from 0.6% to 11% in those older than 90 years, and the prevalence of visual impairment due to age-related macular degeneration rose from 0.8% to 16% in those older than 90 years. CONCLUSIONS: The predominant causes of visual impairment change with age. Recognition of these patterns is fundamental for early diagnosis and treatment of eye disease and, where appropriate, referral for rehabilitation.