Abstract
Purpose :
Axial length (AL) is increasingly used to monitor myopia progression in children. The assessment of excessive eye growth in childhood has proven to be challenging as eye growth varies with age. The aim of this study is to investigate the association between AL eye growth from age 6-9 and from 9-13 years, and to relate eye growth during these periods to risk of myopia and spherical equivalent (SER) at 13 years. The second aim is to validate and extend normative values to existing growth curves for eye growth.
Methods :
A total of 3600 children from the population-based birth cohort study Generation R underwent ocular biometry measurements with AL at ages 6, 9, and 13 years of age, with measurements of objective cycloplegic refractive error at 9 and 13 years. Myopia was defined as mean SER of ≤-0.5D in both eyes. Risk of myopia and effect on SER was calculated with logistic and linear regression adjusted for age and gender. Correlation between growth before and after age 10 was calculated using Pearson correlation. Percentiles were calculated at all ages.
Results :
Children were on average (SD) 6.2 (0.5), 9.8 (0.3) and 13.6 (0.4) years old at the different examinations. Myopia increased from 12.5% at age 9 to 22.2% at age 13. AL increased from 22.36 (0.75) mm at 6 years; 23.10 (0.84) mm at 9 years to 23.48 (0.95) mm at 13 years. AL growth was on average 0.21 (0.08) mm/year between 6-9 years and 0.10 (0.08) mm/year between 9-13 years; this was 0.34 and 0.19 mm/year in myopic children. Each additional 0.01 mm/year growth had an increased risk of myopia OR=1.24 (95%CI 1.21 – 1.27 P <0.001) and -0.10±0.005D (P <0.001) more myopic SER at age 13 years. Each additional 0.01 mm/year extra growth between 6 and 9 years had an -0.10±0.005 (P <0.001) more myopic SER at age 13 years. Correlation between growth before age 10 and after age 10 was 0.39 (P < 0.001). The percentiles followed our earlier designed growth curves based on data at 9 in Generation R and at 15 years in ALSPAC.
Conclusions :
This study validated normative values for AL in European children. Children more than average eye growth had an increased risk of myopia. Every 0.01 mm/year extra growth after age 6 years increased the degree of myopia at age 13 years. These growth data and growth curve charts will help clinicians diagnose excessive eye growth at an early age, and substantiate the instigation of intervention for progressive myopia.
This is a 2020 ARVO Annual Meeting abstract.