Background: Impaired visual acuity is common in older adults. Screening for impaired visual acuity in primary care settings could identify older adults who are unaware of or do not report vision problems, and lead to interventions to improve vision, function and quality of life.
Purpose: To assess the effects of screening for impaired visual acuity in primary care settings in older (age > 65 years) adults.
Data Sources: We searched the Cochrane Controlled Trials Registry and Cochrane Database of Systematic Reviews (through 3rd Quarter 2008) and MEDLINE database (1996 – July 2008) for relevant studies and meta-analyses. We supplemented electronic searches with reviews of reference lists of relevant articles and solicited additional citations from experts.
Study Selection: We selected randomized trials and controlled observational studies that directly evaluated screening for impaired visual acuity in older adults. To evaluate indirect evidence on screening, we also included studies evaluating the diagnostic accuracy of screening tests for impaired visual acuity used in primary care settings, and randomized trials and controlled observational studies of treatments for impaired visual acuity due to refractive errors, cataracts, and age-related macular degeneration that reported clinical outcomes (visual acuity, quality of life, functional capacity, adverse events, or mortality).
Data Extraction: One investigator abstracted data and a second investigator checked data abstraction for accuracy. Two investigators independently assessed study quality using methods developed by the United States Preventive Services Task Force.
Data Synthesis (Results): Direct evidence from three fair-quality cluster randomized trials (N=4,728) found vision screening as part of multi-component primary care intervention associated with no benefits compared to usual care, delayed screening, or no screening on visual acuity or other clinical outcomes. One randomized controlled trial found vision screening by an ophthalmologist in frail older adults associated with an increased risk of falls (relative risk 1.57, 95% CI 1.20 to 2.05) and a trend towards increased risk of fractures (relative risk 1.74, 95% CI 0.97 to 3.11). No other trial evaluated harms associated with screening, and no studies evaluated optimal screening intervals.
Four studies found screening questions associated with low accuracy compared to visual acuity testing or an ophthalmologic examination for identification of vision impairment and four studies found visual acuity testing associated with low accuracy compared to an ophthalmologic examination for identification of any visual condition. Evidence on the diagnostic accuracy of the Amsler grid is limited to one study, and no studies evaluated diagnostic accuracy or utility of fundoscopic examination in primary care settings.
A large population-based study found that about 60% of older adults with vision impairment could achieve visual acuity of 20/40 or better with refractive correction. Based on numerous observational studies, over 90% of patients undergoing cataract surgery achieve visual acuity of 20/40 or better. Antioxidant vitamins and minerals are more effective than placebo for reducing progression of dry age-related macular degeneration (adjusted odds ratio 0.68, 99% CI 0.49 to 0.93), though conclusions are largely influenced by results of a single, large, good-quality trial. For wet age-related macular degeneration, laser photocoagulation (relative risk 0.67 for 6+ lines visual acuity loss; 95% CI 0.53 to 0.83, five trials), photodynamic therapy (relative risk 0.22 for 3+ lines visual acuity loss, 95% CI 0.13 to 0.30, three trials), and vascular endothelin growth factor inhibitors (for 3+ lines visual acuity loss: pegaptanib [two trials] relative risk 0.71, 95% CI 0.61 to 0.84; ranibizumab [two trials] relative risk 0.21, 95% CI 0.16 to 0.27) are superior to placebo for prevention of visual acuity loss, though evidence on laser photocoagulation is limited by methodological shortcomings. Harms of commonly used interventions for uncorrected refractive error, cataract, and age-related macular degeneration appear to be substantially outweighed by benefits, though data on long-term benefits and harms of photodynamic therapy and vascular endothelin growth factor inhibitors are limited.
Limitations: We excluded non-English language studies, could not evaluate for publication bias because of small numbers of trials, included previously published systematic reviews on treatments that met quality threshold criteria, and did not construct outcomes tables.
Conclusions: Direct evidence is relatively limited, but shows that screening for impaired visual acuity 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 risk of falls. Effective treatments (benefits outweigh harms) are available for uncorrected refractive error, cataracts, and age-related macular degeneration. The Snellen chart is the standard for screening for impaired visual acuity in primary care, but its diagnostic accuracy is difficult to assess because a clinically relevant reference standard is not established. There remains no evidence on accuracy of fundoscopic examination by primary care providers. More research is needed to understand why the direct evidence on vision screening in older adults shows no benefit, despite the availability of effective treatments for common conditions associated with impaired visual acuity.