NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Chou R, Dana T, Bougatsos C. Screening for Visual Impairment in Older Adults: Systematic Review to Update the 1996 U.S. Preventive Services Task Force Recommendation [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2009 Jul. (Evidence Syntheses, No. 71.)

  • This publication is provided for historical reference only and the information may be out of date.

This publication is provided for historical reference only and the information may be out of date.

Cover of Screening for Visual Impairment in Older Adults

Screening for Visual Impairment in Older Adults: Systematic Review to Update the 1996 U.S. Preventive Services Task Force Recommendation [Internet].

Show details

2Methods

Using the methods of the USPSTF that are fully detailed in Appendix B and with the input of members of the USPSTF, we developed an analytic framework (Figure 1) and key questions (KQs) to guide our literature search and review. The target population is adults older than 65 years evaluated in primary care settings and not known to have impaired visual acuity, including those with impaired visual acuity despite current use of corrective lenses. We also included studies of vision screening in eye specialty settings, but evaluated their applicability to primary care settings. We defined impaired visual acuity as visual acuity worse than 20/40 but better than 20/200. For treatments, which are typically provided in eye specialty settings, we focused on corrective lenses and photorefractive surgery for uncorrected refractive errors; cataract surgery and antioxidants or vitamins for cataracts; antioxidants or vitamins for dry ARMD; and laser photocoagulation, photodynamic therapy, and VEGF inhibitors for wet ARMD. Outcomes of interest were visual acuity, vision-related function or quality of life, general function or quality of life, falls, accidents, mortality, and adverse events related to treatment (such as surgical complications, keratitis, visual field deficits, loss of vision, and others). We excluded persons with glaucoma or diabetes. 5, 6

Figure 1. Analytic Framework and Key Questions.

Figure

Figure 1. Analytic Framework and Key Questions. KQ 1. Does vision screening in asymptomatic older adults result in improved morbidity or mortality or improved quality of life? KQ 2. Are there harms of vision screening in asymptomatic older adults?

The KQs are:

  • KQ1: Does vision screening in asymptomatic older adults result in improved morbidity or mortality or improved quality of life?
  • KQ2: Are there harms of vision screening in asymptomatic older adults?
  • KQ3: What is the accuracy of screening for early impairment in visual acuity due to uncorrected refractive error, cataracts or age-related macular degeneration?
  • KQ4: Does treatment of early impairment in visual acuity due to uncorrected refractive error, cataracts or age-related macular degeneration lead to improved morbidity/mortality, or quality of life?
  • KQ5: Are there harms of treating early impairment in visual acuity due to uncorrected refractive error, cataracts or age-related macular degeneration?

Search Strategies

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 (search strategies described in Appendix B1). We also reviewed reference lists of relevant articles and queried experts in the field for additional citations.

Study Selection

Studies pertaining to screening, diagnosis, and treatment of impaired visual acuity were selected based on pre-defined inclusion and exclusion criteria developed for each KQ (Appendix B2). Two reviewers evaluated each study at the title/abstract and full-text article stages to determine eligibility for inclusion. The flow of studies from initial identification of titles and abstracts to final inclusion or exclusion is diagrammed in Appendix B3. We focused on studies reporting results in persons 65 years of age or older, but included studies of younger adults if sufficient data in the older age group were not available. We included systematic reviews of randomized trials if they met criteria for a good-quality study, 62 and fair- or good-quality systematic reviews of observational studies when no randomized trials were available. Studies that were excluded after review of the full-text articles and reasons for exclusion are listed in Appendix B4.

Appendix B3. Literature Flow Diagram.

Figure

Appendix B3. Literature Flow Diagram.

Data Abstraction and Quality Rating

We abstracted details about the patient population, study design, data analysis, follow-up, and results. One author abstracted data and another author verified data abstraction for accuracy. We used predefined criteria developed by the USPSTF to assess the internal validity of studies. 63 Two authors independently rated the internal validity of each study as “good,” “fair,” or “poor”. For cluster randomized trials, in addition to standard USPSTF methods for assessing quality of randomized trials (described in Appendix B5), we also evaluated whether the statistical analyses adjusted for the cluster correlation. 64 For diagnostic accuracy studies, we used the diagti procedure (confidence intervals based on the exact method) in Stata (Stat version 10, StataCorp, College Station, TX) to calculate sensitivities and specificities and the cci procedure (confidence intervals based on the normal approximation) to calculate positive likelihood ratios (PLRs), negative likelihood ratios (NLRs), and diagnostic odds ratios (DORs). For all studies we evaluated applicability to populations likely to be encountered in primary care screening settings (e.g., whether patients were recruited from primary care settings, and the inclusion of patients with mild to moderate vision impairment). Discrepancies in quality ratings were resolved by discussion and consensus. We rated quality of systematic reviews using criteria described in Appendix B6 and verified the accuracy of data abstraction by systematic reviews by independently abstracting and rating the quality of all trials comparing a treatment to no treatment, placebo, or sham treatment.

Data synthesis

We assessed overall strength for each body of evidence addressing a particular KQ or part of a KQ (for example, different treatments) using methods developed by the USPSTF. 63 To assign an overall strength of evidence (“good,” “fair,” or “poor”) we considered the number, quality and size of studies, consistency of results between studies, and directness of evidence.

For efficacy of treatments, we reported quantitative estimates for treatment effects from previously published systematic reviews meeting inclusion criteria after verifying data abstraction and analyses. 62 For treatments with new, placebo-controlled trials not included in systematic reviews, we calculated updated relative risks with the new trials and corresponding confidence intervals using a random effects model (Review Manager Version 4.2.8, Copenhagen: The Nordic Cochrane Center, 2003).

For diagnostic tests, we classified PLRs > 10 and NLRs ≤ 0.1 as “large,” PLRs > 5 and ≤ 10 and NLRs > 0.1 and ≤ 0.2 as “moderate,” and PLRs > 2 and ≤ 5 and NLRs > 0.2 and ≤ 0.5 as “small.” 65

External review

We distributed a draft of the report for review by external experts not affiliated with the USPSTF (Appendix B7). Revisions have been made based on their comments.

Views

  • PubReader
  • Print View
  • Cite this Page
  • PDF version of this title (2.0M)

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...