Background:

In 2016, the United States Preventive Services Task Force (USPSTF) concluded that the current evidence was insufficient to assess the balance of benefits and harms of screening for impaired visual acuity in older adults (I Statement). Although the USPSTF found that screening can identify persons with impaired visual acuity and that effective treatments are available for common causes of impaired visual acuity, direct evidence found no differences between vision screening and no screening on visual acuity or other clinical outcomes.

Purpose:

To systematically review the evidence on screening for impaired visual acuity in older adults for populations and settings relevant to primary care in the United States.

Data Sources:

We searched the Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and MEDLINE (through February 9, 2021), reviewed the studies in the prior USPSTF report, and manually reviewed reference lists. Surveillance was conducted through January 21, 2022.

Study Selection:

Randomized controlled trials (RCTs) and controlled observational studies on benefits and harms of screening compared with no screening; studies on diagnostic accuracy of screening tests and instruments (including questionnaires); and benefits and harms of vascular endothelial growth factor (VEGF) inhibitors for wet age-related macular degeneration (AMD) and antioxidant vitamins and minerals for dry AMD in adults age 65 years and older.

Data Extraction:

One investigator abstracted data and a second checked accuracy. Two investigators independently assessed study quality using methods developed by the USPSTF.

Data Synthesis (Results):

A total of 25 studies (N=33,586) were included in this review (13 trials, 11 diagnostic accuracy studies, and 1 systematic review [of 19 trials]). Sixteen studies were carried forward from the 2016 review for the USPSTF, eight studies were new, and the systematic review utilized in the 2016 review for the USPSTF was updated to include six new trials.

Four trials (N=4,819) of screening compared with no screening, usual care, or delayed screening of older adults found no differences in visual acuity or other clinical outcomes. Visual acuity tests (3 studies; N=6,493) were associated with suboptimal diagnostic accuracy for identifying visual conditions compared with a complete examination by an ophthalmologist (sensitivity 0.27 to 0.75 and specificity 0.51 to 0.87); evidence on other screening tests was limited. Three studies (N=5,203) found that a screening question was not accurate for identifying older persons with impaired visual acuity compared with a visual acuity eye chart (sensitivity 0.17 to 0.81 and specificity 0.19 to 0.84).

For wet AMD, four trials (N=2,086) found VEGF inhibitors associated with greater likelihood of ≥15 letters (3 lines) of visual acuity gain (risk ratio [RR] 2.92, 95% confidence interval [CI] 1.20 to 7.12, I²=76%; absolute risk difference [ARD] 10%), <15 letters (3 lines) of visual acuity loss (RR 1.46, 95% CI 1.22 to 1.75, I²=80%; ARD 27%) and having vision 20/200 or better (RR 1.47, 95% CI 1.30 to 1.66, I²=42%; ARD 24%) at 1 year compared with sham injection. VEGF inhibitors were associated with better vision-related function and quality of life measures compared with sham injection at 1 and 2 years; the difference (~8 points on a 0 to 100 scale) was above the minimum clinically important difference threshold.

For dry AMD, a systematic review of 19 trials found antioxidant multivitamins associated with decreased risk of progression to late AMD (3 trials, N=2,445 people, odds ratio [OR] 0.72, 95% CI 0.58 to 0.90) and ≥3 lines visual acuity loss (1 trial, N=1,791 people, OR 0.77, 95% CI 0.62 to 0.96) compared with placebo. Results were primarily driven by the large (n=3,640) Age-Related Eye Disease Study (AREDS). Zinc was associated with decreased risk of progression to late AMD compared with placebo (3 trials, N=3,790 people, OR 0.83, 95% CI 0.70 to 0.98) and decreased risk of ≥3 lines visual acuity loss that was of borderline statistical significance (2 trials, 3,791 people, RR 0.87, 95% CI 0.75 to 1.00). Evidence on the effects of other vitamins and mineral treatments was limited or showed no clear effects on AMD progression or visual acuity. The AREDS trial found zinc use associated with increased risk for hospitalization due to genitourinary causes compared with nonuse (7.5% vs. 4.9%, RR, 1.47, 95% CI 1.19 to 1.80); other serious harms were infrequent, with no differences between groups. The AREDS 2 trial found the AREDS formulation with beta carotene was associated with increased risk of lung cancer compared with the AREDS formulation without beta carotene when current smokers were excluded from the analysis (2.0% vs. 0.9%, p=0.04); almost all lung cancers occurred in former smokers.

Limitations:

Screening trials had methodological limitations that could have attenuated potential benefits; utilized an update to a previously included systematic review on antioxidant multivitamins and minerals for dry AMD; evidence on the effectiveness of treatment for dry AMD relied heavily on results of a single trial (AREDS); non-English-language studies were excluded; too few RCTs to perform formal assessments for publication bias with graphical or statistical methods for small sample effects; and statistical heterogeneity in pooled estimates for VEGF inhibitors compared with sham, though inconsistency was in magnitude (not direction) of effect.

Conclusions:

Impaired visual acuity is common in older adults and effective treatments are available for common causes of impaired visual acuity. Visual acuity testing is the reference standard for identifying impaired visual acuity, but has low diagnostic accuracy compared with an ophthalmological exam for identifying visual conditions not necessarily associated with impaired visual acuity; screening questions have low diagnostic accuracy compared with visual acuity testing. Direct evidence found no significant difference between vision screening in older adults in primary care settings and no screening in visual acuity-related outcomes or other clinical outcomes.