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.