Risk factors associated with myopia onset in pre-myopic children aged 5–9 years old: ATOM3

AIM: Identification of risk factors associated with incident myopia at 1 and 2 years in eyes of young pre-myopic children. METHODS: 150 eyes of 75 placebo-treated pre-myopic children (spherical equivalent (SER) -0.49 to +1.0D) from the Atropine Treatment of Myopia (ATOM3) study were analysed. Cycloplegic SER and axial length (AL) were assessed at 6 month intervals. Univariate and multivariate logistic analyses were used to study associations between myopia incidence and demographic factors, SER, AL, parental myopia and lifestyle factors. Generalised estimating equations (GEE) were used to account for clustering of eyes. RESULTS: 35 (23%) and 59 (39%) eyes became myopic by 1 and 2 years, respectively, with 91 (60%) remaining emmetropic. 74% of eyes with SER of -0.49 to 0.01D became myopic within 1 year. In eyes with SER of 0 to +0.50D, 32% and 55% became myopic at 1 and 2 years, respectively; while only 13% with SER>+0.5D became myopic at 2 years. Myopia progression was greater 6 months prior to myopia onset in eyes becoming myopic (-0.73±0.39D or 0.34±0.15 mm) compared with eyes remaining emmetropic (-0.17±0.28D or 0.13±0.08 mm). Myopia progressions of >0.3 mm or -0.5D within the first year showed the best sensitivity-specificity balance in predicting myopia onset over 1-2 years. No associations were noted with baseline AL, parental myopia, books read and time outdoors. CONCLUSION: Eyes of children aged 5-9 years with a cycloplegic SER <±0.5D and myopic shift more/equal to 0.30 mm or -0.5D within the first year were at higher risk of becoming myopic within the next 2 years.