Abstract
Purpose :
Population-based data on children’s eye growth are rare. This prospective, observational study modelled the developmental trajectory of spherical equivalent refraction (SER) and axial length (AL) in a white population to identify the number of homogenous classes present.
Methods :
Stratified random cluster sampling recruited 1052 white children aged 6-7 years (n=391) and 12-13 years (n=661) (NICER Study). Cycloplegic autorefraction and AL were assessed at baseline and prospectively at 3, 6 and 9 year intervals. Latent growth modelling of SER and AL were conducted using Mplus v7.4. The fit of six models (one to six-class) were used to determine the best fit model for each cohort. Predictive variables for emergent classes were explored for the younger cohort (Odds ratios OR, confidence intervals CI).
Results :
For the younger cohort (6-16 years): a four-class solution was the best fit for SER labelled as ‘Persistent Emmetropes-PEMM’, ‘Persistent Moderate Hyperopes-PMHYP’, ‘Persistent High Hyperopes-PHHYP’ and ‘Emerging Myopes-EMYO’ and a two-class solution fitted AL best (Fig 1 A&B). For the older cohort (12-22 years): a five-class solution was the best fit for SER, labelled as “PHHYP”, “PMHYP”, “PEMM”, “Low Progressing Myopes-LPMYO” and “Moderate Progressing Myopes-MPMYO” and a four-class solution fitted AL best (Fig 2A&B). Those in the EMYO class were significantly more likely to have a longer AL at baseline (OR 2.5, CI 1.05-5.97) and at least one myopic parent (OR 6.28, CI 1.01-38.93). Other variables were not predictive (Gender, socioeconomic status, physical activity, time spent outdoors, time spent doing near work, BMI, breastfed).
Conclusions :
Four distinct classes of refractive development from childhood to teenage years were evident and five distinct classes from teenage years into adulthood. The two-class solution for AL growth in children 6-16 years (compared to four-class for SER) suggests other ocular components, such as lens shape are important determinants of SER alongside AL. Parental history of myopia and longer AL at 6-7 years are risk factors for emergent myopia. These population-based data (not derived from clinical trial control data) are a useful addition to other refractive growth models and can be used to identify, at an early stage, white children who may benefit from myopia intervention.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.