Abstract
Purpose :
Longitudinal changes in choroidal thickness (ChT) have been associated with axial eye growth. The aim was to assess the relationship between seasonal changes in ChT and axial length (AL) in children.
Methods :
Data was collected in 86 primary school children (7–8 y, n=48; 10–11 y, n=38) during the winter (Nov and Jan) and in the following summer in south-eastern Norway (12-hour seasonal difference in daylight availability). Cycloplegic autorefraction (Huvitz HRK-8000A) was obtained in Jan, while measures of AL (Zeiss IOLMaster 700), non-cycloplegic autorefraction (Shin-Nippon Nvision-K 5001), and OCT imaging (Heidelberg Spectralis OCT2 EDI) were obtained at all three timepoints at the same time of day following 15 mins accommodation washout. The central 1 mm ChT was segmented semi-automatically. Baseline (Nov) AL was used to group participants as having no myopia-risk (n=65, 32 males) or myopia-risk/being myopic (n=21, 12 males), where AL was below, or equal/above, the sex- and age-specific 75th percentile in Tideman et al [Acta Ophthalmol. 2018 96:301]. These were 23.36 and 22.79 mm (7–8 y) and 23.82 and 23.27 mm (10–11 y), for males and females. A linear mixed effects model (LMM) was used to analyze the longitudinal data with participant as a random effect, and AL-group and season as fixed effects.
Results :
The average (range) subfoveal ChT was 306±75 um (164–472 um) in 7–8 y and 337±94 um (151–565 um) in 10–11-year-olds with no sex or age differences (all p>0.106). Longer AL was significantly associated with thinner choroids in 10–11-year-olds (R2=0.16, p=0.006), but not in 7–8-year-olds (R2=0.05, p=0.175). The choroid thinned significantly towards summer in 7–8-year-olds (p<0.001), but not in 10–11 y (p=0.340). The LMM showed that the myopia-risk group for 10-11-year-olds had a significantly thinner choroid than the no-risk group (p=0.024), with no interaction between risk groups and season (p=0.476). For the 7–8 y, there were no differences between risk groups, nor interaction with season (all p>0.216).
Conclusions :
The choroid was thicker in 10–11-year-olds and the inverse relationship between ChT and AL was only evident in this group. Seasonal ChT thinning was independent of risk of myopia and only observed in the 7–8-year-old children, indicating that ChT thinning alone may not be a useful predictor of myopia for these age groups.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.