Time trends on the prevalence of myopia in India – A prediction model for 2050

Authors: Priscilla JJ, Verkicharla PK.

Geographical coverage: India

Sector: Burden of disease

Sub-sector: Prevalence and time trends

Equity focus: None specified

Study population: School- and population-based  

Review type: Other review

Quantitative synthesis method: Narrative synthesis and meta-analysis

Qualitative synthesis method: Not applicable

Background:

The surging prevalence of myopia in India remained unpredictable as the dramatic increase in the prevalence rates of myopia in East Asian regions have caught global attention. While the prevalence of myopia in rural regions of India did not change much over the past two decades, a significant increase in myopia prevalence was noted in urban school children (aged 5 to 15 years).

Objectives:

This study aimed to predict myopia prevalence in urban Indian children and to describe the generational effect of myopia in different age groups over the next three decades from the year 2020.

Main findings:

Authors included seven studies, five school-based and two population-based studies, conducted in urban areas of India including Andhra Pradesh, New Delhi, Kolkata, Hyderabad, Delhi, Chennai and Haryana.

Authors found an increase in prevalence of myopia in children aged between 5 and 15 years old of 4.4% in the year of 1999 to 21.1% in 2019. The predictions based on a slope of 0.8% per year (4.05% for every five years) indicate, according to the authors, that the prevalence of myopia will likely increase to 31.89% in 2030, 40.01% in 2040 and 48.14% in 2050.

Across the different age groups, authors note that the ageing effect leads to a significant increase in myopia prevalence over the next three decades, probably doubling the numbers of the prevalence of myopia in adults by 2050. Authors predict an increase of 10.5% increase in the prevalence of myopia across all age groups.

Based on these findings, authors predict a possible future epidemic of myopia in India within a few decades if, like the situation on East Asian countries, preventative measures are not put in place and changes in lifestyle are not promoted to counteract the condition in India. They also report a need for better designed eye care services focusing on anti-myopia strategies to control the rise of myopia in India.

Methodology:

Authors included population-based/school-based studies that investigated myopia prevalence in children aged between 5 and 15 years of age in India and were published between 1995 and March 2020 and written in English language only. Authors included studies from the urban areas of India only. For this review, studies that defined myopia as a spherical equivalent ≤-0.50 D were included. To identify eligible studies, authors searched PubMed and reviewed references of included studies. The quality of methods was assessed in the eligible studies.

To analyse the best fit for the prediction model, the baseline prevalence data plotted against years were fitted with multiple mathematical regressions (linear, second order polynomial, third order polynomial and exponential) and the quality of the fit was assessed by the coefficient of determination (R²) values, sum of squared residuals (SSR) and statistical significance of F-test using IBM SPSS statistical software. The R² and SSR values were further inspected by changing the type of study (population-based or school-based) to assess the sensitivity of each model. Authors note considering that only two population based studies were included, the sensitivity analysis was not conducted by eliminating these studies individually.

To describe the generational effect on myopia prevalence for the next three decades, the prevalence of myopia including children and adults from available literature from 1999 to 2020 was plotted against age as the baseline. The predicted estimates for the years 2030, 2040 and 2050 from the 5 to 15-year age group obtained from the linear regression model were used as a reference to show the generational effect, that is, to describe the overall prevalence of myopia among children and adults over a period of three decades.

Applicability/external validity:

Authors acknowledge restricting the inclusion of studies from the urban areas of India in the review. Therefore, authors do not generalise the findings of this review.

Geographic focus:

The findings of this review are based on school- and population-based studies conducted in urban regions of India, therefore, findings may be applicable to this geographical region only. Authors note findings of this review are not consistent to other studies from other low and middle income regions.

Summary of quality assessment:

Important limitations were identified in this review. This review included published literature written in the English language and was based on a single database search. The search was not comprehensive enough to ensure that all available literature was identified. In addition, methods used to screen studies for inclusion and extract data of included studies were not reported. This is an important limitation, because if rigorous methods were not employed, findings from the review may be biased. Quality assessment of each included study was not reported; therefore, it is not clear if the findings of this review are based on high, medium or low quality studies. Based on these limitations, there is low confidence in the conclusions about the effects of this study.