Refractive error evidence gap map

Kalpana gets her eyes tested in the Sundarbans.

What this map shows

At Sightsavers, our EGMs summarise, appraise, and present evidence from systematic or literature reviews.

The refractive error gap map compiles evidence from 188 reviews. Five of these reviews cover more than one thematic area and were thus included in the EGM multiple times. Among these, 95 reviews address the treatment of refractive error, 53 tackle the burden of disease (epidemiology), and 19 cover risk/prevention of refractive error. The remaining reviews address screening (10), quality of life (four), quality of clinical care (four), cost benefit (four), quality of non-clinical care (four), and access to services (two). This gap map reveals clear evidence gaps at the health-systems sector level, with no reviews identified around access to healthcare services.

In response to the authors’ research questions, 103 reviews provide strong evidence, 61 reviews present weak or no evidence, and 27 reviews yield inconclusive (mixed) results. The reviews were assessed for quality: 90 reviews are graded as low quality, 77 as medium quality, and 24 as high methodological quality.


Find out more about the key messages from this EGM in our Refractive error evidence brief.

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This evidence gap map was last updated in 2024.
Help us keep this gap map up to date by sending us an email: [email protected]


Sightsavers (2015). Refractive Error Evidence Gap Map [online] Available at:

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