Anisomyopia is a natural experimental paradigm that compares dose response between fellow eyes. This study is the first to explore whether orthokeratology (ortho-k) has a dose-response effect on axial length growth and reduces the interocular difference in axial length in anisomyopic children.
The purpose of this study was to compare the effect of ortho-k on axial length elongation between the fellow eyes of anisomyopic children.
In this retrospective study, 49 anisomyopic children who wore ortho-k lenses were assigned to the anisomyopic ortho-k group. Based on the one-to-one match principle (same age and proximate spherical equivalent), high-isomyopic and low-isomyopic groups each enrolled 49 isomyopic children who wore ortho-k lenses with spherical equivalent similar to that of the more myopic eye and the less myopic eye in the anisomyopic ortho-k group, respectively. Forty-nine anisomyopic children who wore spectacles were enrolled in the anisomyopic spectacle group. At baseline and at 1- and 2-year visits, axial length was measured. Axial length elongation and interocular difference in axial length were compared.
In the anisomyopic ortho-k group, the less myopic eyes exhibited more axial length elongation than did the more myopic eyes during 1- and 2-year treatment periods (P < .01). However, there was no significant difference in axial length elongation between the fellow eyes in the isomyopic groups and anisomyopic spectacle group. At the 2-year visit, the interocular difference in axial length of children in the anisomyopic ortho-k group significantly decreased from 0.72 ± 0.34 to 0.56 ± 0.38 mm (P < .05). In contrast, ortho-k lens–wearing isomyopic children or spectacle-wearing anisomyopic children did not show a significant change in interocular difference in axial length.
Orthokeratology could reduce the amount of anisomyopia in children primarily through stronger myopia control in the more myopic eye.