Choroidal thickness associated with spherical equivalent in healthy young adults: The Raine Eye Health Study

Abstract

Purpose: : It has been shown that an active change in choroidal thickness is important in the achievement of emmetropia in animals, and that similar changes occur in humans subjected to short-term unilateral image blur. Our aim was to measure subfoveal choroidal thickness (SFCT) in healthy young adults and to analyse correlation with other measures of ocular biometry, anthropometric measures and birth parameters.

Methods: : Prospective study of 271 eyes of 271 participants from the Raine Eye Health Study, aged 19 to 22 years old. Participants underwent enhanced-depth imaging optical coherence tomography (EDI-OCT) imaging with the Spectralis HRA-OCT, with 2 vertical and 2 horizontal high-resolution scans through the fovea. An average measurement was taken from the 4 individual EDI-OCT scans. Measurements of axial length, central corneal thickness, intraocular pressure, lens thickness, refractive error, height and weight were also taken. Birthweight and gestational age were prospectively collected from the participant’s antenatal records. Data from the right eye were used in multivariate linear regression analysis to identify statistically significant associations.

Results: : Subfoveal choroidal thickness was normally distributed, with a mean and standard deviation of 373±83µm (Range: 162-660µm). Spherical equivalent (β=15.7, 95%CI=7.2-24.1, p<0.001) was significantly associated with subfoveal choroidal thickness, whereas axial length was not (β=-14.0, 95%CI=-28.8-0.8, p=0.065). From univariate analyses, SFCT can be estimated by the following equation: SFCT = 373 + 20.4 x SE (D).

Conclusions: : This large study investigating the relationship between SFCT and ocular biometry has demonstrated that spherical equivalent is the most important predictor of SFCT in healthy young adults. This finding opens a new avenue of research into the aetiology of myopia.

Keywords: myopia • choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)