Abstract
Purpose:
To develop growth curves for anterior globe width and determine how those growth curves depend on age, axial length, and refractive error.
Methods:
Subjects included 315 children who were enrolled in the Longitudinal Evaluation of Myopia and Ciliary Muscle Changes between the ages of 6 and 12 years (mean = 8.8 years, SD = 1.4). The anterior scleral chord (ASC) was measured from Visante anterior segment images as the horizontal width of the globe behind the iris. Axial length and cycloplegic spherical equivalent refractive error were measured with the IOLMaster and Grand Seiko autorefractor, respectively. We fitted multilevel growth curves of ASC as a function of age (centered at 9 years), while testing the contribution of mean axial length, change in axial length, mean spherical equivalent refractive error, gender, and various interaction terms.
Results:
The final growth model for ASC included significant associations with age (β = −0.02, p = 0.03), mean refractive error (β = 0.11, p ≤ 0.0001), mean axial length (β = 0.45, p ≤ 0.0001), and an interaction between age and refractive error (β = −0.02, p = 0.04); it also included gender which was not significant (β = 0.07 mm, p = 0.1). The interaction between age and axial length and the change in axial length were not significant and were therefore not included in the final model.
Conclusions:
In a manner that is consistent with our previous presentation of the cross-sectional relationship between ASC and refractive error, it appears that longitudinal growth of ASC is complex and is different for myopes versus hyperopes. The final model suggested that overall, more hyperopic eyes had a wider ASC, but that the growth in ASC was different over time depending on refractive error, with ASC decreasing over time in hyperopic eyes while increasing over time in myopic eyes. Across all refractive errors, ASC decreased by a very small amount over time, and generally longer eyes tended to have a wider ASC. The growth in ASC, however, was not dependent on axial length.
Keywords: 605 myopia •
677 refractive error development •
550 imaging/image analysis: clinical