The prevalence and progression of astigmatism and myopia in children

Optometrists are commonly asked how to manage and reduce progression of refractive errors. Epidemiological studies on refractive error are not representative of optometric practices. Therefore this study aimed to provide knowledge on prevalence and progression of astigmatism and myopia in children, allowing optometrists to use information collected routinely to advise on potential for refractive change, and to more accurately determine when the next examination should be. It also investigated the possible influence of astigmatism and myopia on one another. It was the first to investigate birth season and refractive progression,and in the UK to assess the influence of birth season on astigmatism and myopia in children. This retrospective study analysed 900 subjective refractions of children under 19years of age (mean 11.1 years) from two optometric practices in Liverpool. A subset of 242 of these children, tested longitudinally for a mean 5.97 years, was assessed for progression of astigmatism and myopia, using Decision Tree statistical Analysis to determine a possible association between astigmatism and myopia progression. Cross-sectional data showed that boys were more likely to have astigmatism than girls (p = 0.004). Age affected astigmatic axis, with against-the-rule and oblique astigmatism more prevalent in the older children, and with-the-rule prevalence reducing with age (p = 0.004). Myopia increased with age (p = < 0.0001). Astigmatism increased by 0.04D/year (SD 0.087), and myopia by -0.15D/year (SD0.23D). The presence of astigmatism was related to faster astigmatic progression(p = < 0.0001). Being myopic was the sole risk factor for faster myopic progression(p = < 0.0001). Birth season was unrelated to prevalence or progression of refractive error. Advice on how sex, age and birth season may influence refraction can be discussed with patients and their families. Progression of astigmatism and myopia were not linked, suggesting that whilst they may share some risk factors, they appear to be independent of one another.