Myopia is responsible for around one-third of global uncorrectable visual impairment

Published:

Research Abstract Summary

Paper Title: The Role of Myopia in 2020 Uncorrected Global Visual Impairment

Authors: Monica Jong (1), Noel Brennan (1), Mark Bullimore (2)

  1. Johnson and Johnson Vision
  2. University of Houston

Date: May 2022

Reference: ARVO Meeting 2022, Denver [Link to conference abstract]

Summary

This study aimed to estimate the global prevalence of uncorrectable visual impairment (VI) (20/40 or worse) in 2020. The global population in 2020 is 7.79 billion people, of whom 2.64 billion (33.9%) are myopic and 0.46 million have high myopia (<–5D). 

The estimated global population with uncorrectable VI is 113 million, which equates to 1.5% of the population. 60 million of these people are myopic and 32 million of these cases can be directly attributed to increased risk of eye disease associated with myopia. This means an estimated 29% of the cases of uncorrectable VI is attributable to myopia-related disease. Over 40% of these patients are below 60 years of age. This provides insight into the mammoth burden of disease that myopia-related disease creates globally. 

At 65 years, myopes comprise 60% of individuals with VI, with half of the visually impaired being myopes at 81 years.  

The authors predict that in 2020, 1% increase in myopia prevalence results in an additional 1.2 million VI. Projecting for 2050, each 1% increase in myopia is associated with 2.7 million increased VI.

What does this mean for my practice?

This provides eye care practitioners with a better understanding of the prevalence of uncorrectable visual impairment worldwide, with 29% of cases of uncorrectable visual impairment is attributable to myopia-related disease.

The globally increasing prevalence of myopia and myopia-related disease will likely see this number rise in the future. This drives the impetus to implement measures to control myopia development progression in clinical practice, and as a corollary the development of myopia-related pathology.

What do we still need to learn?

Further research is required to treat diseases associated with myopia to reduce VI, along with programs that reduce myopia prevalence and severity.

Abstract

Title: The Role of Myopia in 2020 Uncorrected Global Visual Impairment

Authors: Monica Jong, Noel Brennan, Mark Bullimore

Purpose: Previous estimates of the prevalence of global uncorrectable visual impairment (VI) have not accounted for the increasing prevalence of myopia, particularly in older individuals. We estimate the global prevalence of uncorrectable VI in 2020 accounting for the distribution of both age and myopia.

Methods: Age distribution of the global population in 2020 were taken from www.populationpyramid.net. Overall prevalence of myopia (<–0.50 D) of 33.9% was used, based on Holden et al. (2016). Distribution of myopia, by severity, was calculated using the model of Brennan et al. (2020) Uncorrectable VI as a function of age and refractive error was modelled by multiple linear regression (Bullimore et al., 2021) from a large data set of an advanced European population (Tideman et al., 2016). This data set is agnostic with respect to the disease condition associated with VI. By convolving the distributions of myopia and age with the cumulative risk of VI, the number of individuals with uncorrectable VI in 2020 was calculated.

Results: The 2020 global population is 7.79 billion, of whom 2.64 billion are myopic and 0.46 million have high myopia (<–5D). The cumulative odds of uncorrectable VI (20/40 or worse) is 10(0.057Age – 0.122Rx – 4.03) and the estimated global population with uncorrectable VI is 113 million (1.5%). Of these, 60 million are myopes compared with 53 million non-myopes. An estimated 32 million cases of VI (29%) can be directly attributed to increased risk of eye disease associated with myopia; > 40% of cases below 60 years. At 65 years, myopes comprise 60% of individuals with VI, while representing 33.9% of the population. At 81 years, myopes still account for half of the visually impaired.

Conclusion: Assuming that the data from Tideman et al. are applicable to the global population, we estimate that some 29% of global uncorrectable VI is attributable to myopia. Failure to account for the increasing prevalence of myopia among the aging population leads to a substantial underestimate of the prevalence of VI. In our 2020 model each 1% increase in myopia prevalence results in an additional 1.2 million VI. Projecting for 2050, each 1% increase in myopia is associated with 2.7 million increased VI. Approaches that treat diseases associated with myopia are needed to reduce VI, along with programs that reduce myopia prevalence and severity.

Clare Maher_small

About Clare

Clare Maher is a clinical optometrist in Sydney, Australia, and a third year Doctor of Medicine student, with a keen interest in research analysis and scientific writing.