To the Editor:

Well-conducted systematic reviews and meta-analyses (SRMAs) can serve as a basis for formulating clinical practice guidelines [1,2,3], identifying areas where there is insufficient evidence to answer a research or clinical question [2], and minimizing duplication of effort (“research waste”) [3,4,5]. To ensure that existing systematic reviews in eyes and vision are identifiable and accessible, we constructed a database of SRMAs to inform decision-making and to identify gaps in eye and vision research.

Methods

We searched PubMed/MEDLINE, Embase, and The Cochrane Library (search strategies found in Appendix) annually for SRMAs that met the following eligibility criteria: (1) the publication reported on at least one eye/vision condition and (2) the publication described one or more systematic reviews and/or meta-analyses. Research assistants worked independently, in pairs, to screen titles/abstracts and review full texts for records which were labeled as an SRMA or met the National Academy of Medicine’s definition of an SRMA [1]. We classified the reviews by condition and summarized bibliographic characteristics.

To support the American Academy of Ophthalmology’s updating of Preferred Practice Patterns (methods reported elsewhere), we assessed the reliability of SRMAs that had addressed the effectiveness of therapeutic and preventive interventions for cataract, corneal diseases, glaucoma, refractive error, and retinal diseases [2,3,4].

Results

We identified 19,964 potentially relevant records as of July 2020; among them, 4786 met our inclusion criteria (Supplementary Fig.). Most (4692/4786, 98%) were published after 2000 (Table 1). Among all journals, The Cochrane Library contributed more systematic reviews than any other journal (325/4786, 7%) (Table 1). The conditions with the most SRMAs were glaucoma (639/4786, 13%), diabetic retinopathy (486/4786, 10%), and age-related macular degeneration (427/4786, 9%). Approximately 30% of all SRMAs in the database are for retinal and vitreous diseases if considering all retinal sub-conditions. Of 692 reviews assessed for reliability (full results reported elsewhere), the proportion of reliable systematic reviews varied by condition from 28% (corneal diseases) to 66% (refractive error) (Table 1).

Table 1 Characteristics of records included in the database of eyes and vision systematic reviews, N = 4786 (as of July 2020).
Full size table

Discussion

To our knowledge, our database is the first database of SRMAs for eyes and vision. Our database provides a comprehensive view of the landscape of eye and vision primary research, secondary analyses, meta-analyses, and an “overview” of reviews. Using our database: investigators can support the scientific premise underlying their research questions or identify “research gaps” that need further investigation; sponsors and reviewers of applications for research funding can evaluate the novelty and significance of proposals; journal editors and peer-reviewers can gauge the scientific value of the research reported in newly submitted manuscripts; guideline developers can identify evidence to support recommendations; and patients can use the plain language summaries available in some SRMAs to improve their understanding of eye conditions [5].

Members of the public can request access to view the database through the Cochrane Eyes and Vision Website (https://eyes.cochrane.org/resources/cev-database-systematic-reviews-eyes-and-vision). Users should note that we included SRMAs regardless of their potential reliability; we have published criteria that users of our database can use to assess the reliability of SRMAs [2,3,4]. We also are committed to updating the database annually as long as resources permit.