Do volume, height and width of the eye determine refractive error? Results from 10-year-old European children from the Generation R Study.

Abstract

Purpose : Axial length of the eye has a high association with refractive error, but less is known about volume and height and width of the eye. The aim of this study is to determine the association between MRI-derived width, height of the eye, as well as the volume of the vitreous chamber and refractive error in children; and to examine correlation between MRI-derived measures and ocular biometry.

Methods : A total of 3757 children of the population-based birth cohort study Generation R underwent a T2-weighted MRI scan (1.5T), and ocular biometry (Zeiss IOL-master 500). Cycloplegic refractive error measurements were available in a subset (n = 2415). Volumes and dimensions of each eye were derived from MRI using an automated algorithm based on a training set of manual segmentations. Associations between ocular biometry, refractive error, anthropometry, and MRI measurements (average of both eyes) were tested using Pearson correlation. Differences between refractive error groups were analyzed with ANOVA.

Results : Children were 10.1 (SD 0.6) years old, 51.5% were girls and 12% myopic. The correlation between corpus vitreous length on MRI and axial length measured with IOL master was 0.86. Volume of the corpus vitreous was 6.35(±0.68)cm³. The association between refractive error and MRI-derived corpus vitreous length (-0.51; P <0.001) was higher than the association between refractive error and MRI-derived height (-0.30; P <0.001) and width of the eye (-0.10, P <0.001). Conversely, width of the eye had higher association with body height (0.25; P <0.001) and birthweight (0.18 P <0.001) than corpus vitreous length (0.18 and 0.14 respectively; both P < 0.001). Myopic eyes (SE ≤-0.5D) had a 0.97 cm³ (P <0.001) larger corpus vitreous volume than hyperopic (SE≥ +2.0D) eyes.

Conclusions : Already at a young age, refractive error is predominantly determined by axial length and less by height and width of the eye, whereas height and width have a stronger association with body height and birthweight. This suggests that myopic eyes have undergone the largest shift in corpus vitreous length, and least change in the width of the eye. Longitudinal studies of eye shape are needed to test its effect on refractive error development prospectively.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.