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

Purpose: Scotland has comprehensive child vision screening at age 3.5-5.5 years of age, with similar to 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 (similar to 5000-6000 annually) for 3 years before and 2 years following the COVID-19 pandemic, 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 and 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 5 years. Median SER (interquartile range) in 2013-14, 2014-15, 2015-16, 2020-21 and 2021-22 was +1.38 D (+0.50 to +2.75), +1.38 D (+0.25 to +2.63), +1.38 D (+0.50 to +2.75), +1.13 D (+0.25 to +2.25) and +1.25 D (+0.38 to +2.25), respectively. The increase in myopia was statistically significant in each of the last 2 years compared with each of the first 3 years (p < 0.0005). The proportion of myopes (<=-0.50 D) increased from <7.8% annually in 2013-16 to 11.51% in 2020-21 and 10.65% in 2021-22 (linear trend: r(2) = 0.94, p = 0.006). Associations between the proportion of children in each HB with myopia and: (1) deprivation index was low and not statistically significant; (2) the proportion of the population in the most urban environments was high (r(2) = 0.79; p = 0.003); (3) the proportion of dwellings that were flats/apartments was also high (r(2) = 0.83, p = 0.002). Conclusions: In this predominantly Caucasian population, the proportion of children with myopia has increased post-COVID. A strong association exists between myopia and living in flats/apartments and urbanicity, but not with a deprivation index.