Abstract
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.
Conclusions :
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.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.