Abstract
Abstract: :
Purpose:We report on myopia progression in 7376 myopic children of mixed gender and ethnicity aged between 5 and 15 years of age with the purpose of 1) providing a current comprehensive cross–sectional data base on myopia progression specifically for UK children; 2) comparing progression data with a recently published multicenter US study on refractive error change between 6 and 14 years of age (CLEERE study Zadnik et al. Optometry & Vision Science, 2003: 80; 226–236); 3) informing prospective clinical trials that utilise optical and/or pharmaceutical control of myopia progression. Methods:Data were obtained from electronic practice data records of community optometry practices (N= 61) within the UK West Midlands conurbation. Refractive error data were obtained for children who had undergone a non–cycloplegic routine optometric examination between January 2002 and January 2003. Data were filtered to include only those children with a mean spherical myopic error of –0.50D or more. Results:The mean sample size per year group was 671 (SD 531) with a range from 56 (5 years) to 1327 (15 years). The mean level of myopia across all years was –1.58D (SD 1.43). The percentage of children with high myopia (≥ 6D) did not differ significantly between age groups (p =0.36). Analysis of mean level of myopia across years showed significant linear and inverse quadratic effects (linear p=0.007, quadratic p=0.002) and indicating a peak at 9 years of age corresponding to –1.43D (SD 1.17) and levels of –1.68 (SD 1.48) and –1.64D (SD 1.38) for 5 and 15 years of age respectively. Whereas no clear trend was evident for data between 5 and 8 years of age, a clear monotonic increase in mean sphere myopia of 0.04D per annum was evident between 9 years and 15 years of age, with a maximum change of –0.09D occurring between 12 and 13 years. Conclusions:Progression data for myopic UK children show similar trends to those reported by the CLEERE study on 2583 US children unselected for refractive error. The trends suggest that optimum entry age for clinical trials aiming to control juvenile myopia progression, is 9 years which would preclude the potential compliance and ethical constraints associated with younger children.
Keywords: myopia • clinical (human) or epidemiologic studies: natural history • refraction