Increasing myopia in Scotland at age 3.5-5.5 years: a retrospective epidemiological study

Abstract

Purpose: Scotland has comprehensive child vision screening at age 3.5-5.5 years, with ~85% participation (40,000-50,000 screening episodes annually). Orthoptists deliver the screening, including presenting vision, cover test, and other tests. Screening failures are referred for eye examinations, including cycloplegic refraction. The study aims to report refractive error data from these examinations (~5,000-6,000 annually) for three years pre- and two years postpandemic and to investigate correlations between myopia and socio-economic factors. Methods: Right eye data from eight Scottish Health Boards (HB) are reported for spherical equivalent refraction (SER) for the years 2013-14, 2014-15, 2015-16, 2020-21, 2021-22. Associations were investigated between the proportion of the sample in each HB with myopia and the proportion of the population in each HB with different levels of deprivation index, classification on a rural/urban continuum, and dwelling type. Results: Refractive error frequency distributions revealed a myopic shift in SER over the five years. Median SER (interquartile range) was, in 2013-14, +1.38D (+0.50 to +2.75); 2014-15, +1.38D (+0.25 to +2.63); 2015-16, +1.38D (+0.50 to +2.75); 2020-21, +1.13D (+0.25 to +2.25); 2021-22, +1.25D (+0.38 to +2.25). The increase in myopia was statistically significant in each of the last two years compared with each of the first three (p<0.0005). The proportion of myopes (≤-0.50D) increased from <7.8% annually 2013-16 to 11.51% in 2020-21, 10.65% in 2021-22 (linear trend: r 2=0.94, p=0.006). Associations between the proportions of children in each HB with myopia and: deprivation index was low and not statistically significant; proportion of population in the most urban environment was high (r2 = 0.79; p=0.003), and proportion of dwellings that were flats/apartments was high (r2 = 0.83, p=0.002). Conclusions: In this predominantly Caucasian population, proportions of children with myopia have increased post-COVID. A strong association exists between myopia and living in flats/apartments and urbanicity, but not with a deprivation index