Age-specific causes of bilateral visual impairment

Objective: To describe the age-specific prevalence of common eye diseases c ausing bilateral visual impairment and estimate the total number of Austral ians with cause-specific visual impairment. Methods: Cluster-stratified random sample of 5147 residents aged 40 years a nd older from urban and rural areas and aged-care facilities. Participants completed a standardized interview and eve examination. Four levels of bila teral visual impairment were defined: less than 20/40 to 20/60 and/or homon ymous hemianopia (mild), less than 20/60 to 20/200 or better and/or less th an 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 les s than 10/200 and/or less than 5 degrees radius field (profound). The major cause of vision lass was identified for all participants found to be visua lly impaired. Results: Uncorrected refractive error was the most common cause of bilatera l 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 visu al impairment due to diabetic retinopathy was 0.7%, in 50- to 59-year-olds and 0.8% in these older than 80 years. Visual impairment due to glaucoma ha d a prevalence of 0.7% among 60-year-olds and rose to 4% of those older tha n 90 years. The prevalence of visual impairment due to cataract (only prese nt in those aged 70 years or older) rose from 0.6% to 11% in those older th an 90 years, and the prevalence of visual impairment due to age-related mac ular degeneration rose from 0.8% to 16% in those older than 90 years. Conclusions: The predominant causes of visual impairment change with age. R ecognition of these patterns is fundamental for early diagnosis and treatme nt of eye disease and, where appropriate, referral for rehabilitation.