Screening older adults for impaired visual acuity: a review of the evidence for the U.S. Preventive Services Task Force.

BACKGROUND: Impaired visual acuity is common in older adults. Screening for impaired visual acuity could lead to interventions to improve vision, function, and quality of life.
PURPOSE: To update the 1996 U.S. Preventive Services Task Force evidence review on benefits and harms of screening for impaired visual acuity in primary care settings in adults age 65 years or older. DATA SOURCES: MEDLINE and the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews were searched for studies published in English from 1996 to July 2008. STUDY SELECTION: Randomized trials and controlled observational studies that directly evaluated screening for impaired visual acuity in older adults were selected. To evaluate indirect evidence on screening, investigators included studies of diagnostic test accuracy and systematic reviews, randomized trials, and controlled observational studies of treatments for uncorrected refractive errors, cataracts, and age-related macular degeneration (AMD). DATA EXTRACTION: Details were abstracted about the patient sample, study design, data analysis, follow-up, and results. Quality was assessed by using predefined criteria. DATA SYNTHESIS: Direct evidence on screening and evidence on accuracy of diagnostic tests were synthesized qualitatively. For benefits and harms of treatments, quantitative estimates for treatment effects from good-quality systematic reviews were reported or relative risks using a random-effects model were calculated. Direct evidence shows that screening for vision impairment in older adults in primary care settings is not associated with improved visual or other clinical outcomes and may be associated with unintended harms, such as increased falls. Effective treatments are available for uncorrected refractive error, cataracts, and AMD. A visual acuity test (for example, the Snellen eye chart) is the standard for screening for vision impairment in primary care, but its diagnostic accuracy is uncertain because no studies compare it against a clinically relevant reference standard. There remains no evidence on accuracy of funduscopic examination. LIMITATIONS: A relatively small number of primary studies and methodological shortcomings made it difficult to reach conclusions with a high degree of confidence. In addition, studies not published in English and studies of community- or home-based screening were not included.
CONCLUSION: More research is needed to understand why direct evidence shows no benefits of screening, even though impaired visual acuity is common and effective treatments are available.