Myopia over the lifecourse: prevalence and early life influences in the 1958 British birth cohort

Purpose: To investigate the hypothesis that the excessive growth of the eye in myopia is associated with general growth and thus influenced by early life biological and social factors, and that these associations underlie recent secular trends of increasing prevalence and severity of myopia.

Design: Cohort study.

Participants: A total of 2487 randomly selected 44-year-old members of the 1958 British birth cohort (27% subsample).

Methods: Diverse and detailed biological, social, and lifestyle data have been collected by following members since birth through a series of clinical examinations or face-to-face interviews carried out by trained examiners. At 44 years, cohort members underwent autorefraction using the Nikon Retinomax 2 (Nikon Corp., Tokyo, Japan) under non-cycloplegic conditions. A lifecourse epidemiologic approach, based on 4 sequential multivariable "life stage" models (preconceptional; prenatal, perinatal, and postnatal; childhood; and adult), was used to examine the influence of early life biological, social and lifestyle factors, growth patterns, and "eye-specific" factors on myopia.

Main outcome measures: Myopia severity (all, mild/moderate: spherical equivalent -0.75 to -5.99 diopters [D]; severe: ≥-6.00 D extreme vs. emmetropia -0.74 to +0.99 D) and myopia onset (early [<16 years] vs. later).

Results: A total of 1214 individuals (49%; 95% confidence interval, 48.8-50.8) were myopic (late onset in 979 [80.6%]). Myopia was positively associated with low birthweight for gestational age, gender, greater maternal age, higher paternal occupational social class, and maternal smoking in early pregnancy. Myopia was independently associated with proxy markers of near work and educational performance, with some differences by onset and severity. In adults, greater height and higher educational attainment and socioeconomic status were associated with myopia.

Conclusions: Trends in the key influences on child health and growth identified as novel putative risk factors in this study are consistent with global trends of increasing myopia: increasing births to older mothers, increasing rates of intrauterine growth retardation and survival of affected children, increasing persistence of smoking in pregnancy, and changing socioeconomic status. Prospects for prevention of myopia would be improved by a paradigm shift in myopia research, with lifecourse and genetic epidemiologic approaches applied in tandem in large unselected populations.