Methodological quality of the review: Medium confidence

Author: Sethu Sheeladevi, Bharani Seelam, Phanindra B Nukella, Rishi R Borah, Rahul Ali, Lisa Keay

Region: India

Sector: Refractive error, uncorrected refractive error and presbyopia

Subsector: Prevalence of RE

Equity focus: No

Study population: Adults

Type of programme: Community based

Review type: Other review

Quantitative synthesis method: Systematic review and meta-analysis

Qualitative synthesis method: Not applicable

Background: Refractive error (RE) is one of the most common ocular conditions affecting all age groups. Despite the availability of a cost‑effective intervention to address this problem, uncorrected refractive error (URE) is a major public health challenge. There has been an increase in the number of population‑based studies from India in the last decade on various eye conditions to determine the prevalence of REs among various age groups across different populations. However, a variety of methodologies and different definitions have been used to make these estimates.

Objectives: This study aimed to determine the prevalence of REs among adults aged ≥30 years in India and the need for refractive services through estimates of the prevalence of URE and uncorrected presbyopia.

Main findings: Eighteen studies that reported prevalence of REs were included in the final analysis. Fifteen studies were included from South India, one each from Western and Central India, and one study covered 15 states across India. The prevalence of RE of at least 0.50 D of spherical equivalent ametropia was 53.1% [(95% confidence interval (CI): 37.2-68.5), of which myopia and hyperopia was 27.7% and 22.9%, respectively. The prevalence of URE was 10.2% (95% CI: 6.9-14.8), but heterogeneity in these estimates was very high. The prevalence of uncorrected presbyopia was 33% (95% CI: 19.1-51.0).

Methodology: Authors included all incidence and prevalence reports from epidemiological studies. We also reviewed all relevant national, regional and international reports published from 1990 onwards. The search was performed on Medline, Embase, CINAHL and the Cochrane Library from 1990 to 2018. (The date of the last search was September 2018 via OVID and EBSCOHOST.) The search was based on medical terms using MeSH for medical subject headlines and keywords to search in the title and abstract. RE was defined by spherical equivalent (SE) ametropic with the two major subgroups: myopia as SE worse than -0.50 D and hyperopia as SE worse than +0.50 D. URE was defined as presenting VA <6/18 and improving to ≥6/18 on using a pinhole in either eye or with spectacle correction. Uncorrected presbyopia was defined as binocular presenting near vision <N8 and improving to ≥N8 with correction and presenting distance VA of at least 6/18 in the better eye. Both the lead and second reviewers (SB) assessed the included studies independently based on the abstract and title according to the inclusion criteria, and shortlisted the studies for full-text review. Methodological quality assessment was done independently on the full‑text of shortlisted studies, using the critical appraisal checklist developed for prevalence studies by Munn et al. 2014. Analysis: heterogeneity was performed using the χ2 test on Cochrane’s Q statistic and quantified by calculating the I². A value of 0% indicates no heterogeneity and larger values indicate increasing levels of heterogeneity.

Applicability/external validity: Not discussed, the authors did not acknowledge limitations to consider when reading the results. In addition, the review was focused on India’s population, which limited the external applicability of the results to other populations, for example.

Geographic focus: Focus on Indian population.

Summary of quality assessment:

There is medium confidence in the conclusions about the effects of this study, as authors did not conduct thorough searches of the literature to ensure that all relevant studies were identified.