Assessing the change of anisometropia in unilateral myopic children receiving monocular orthokeratology treatment

Background: This study aimed at comparing the inter-eye axial elongation difference in order to evaluate the change of anisometropia in unilateral myopic children wearing monocular orthokeratology (Ortho-K) lens. Methods: In this retrospective cohort study, we recruited monocular myopic subjects treated with monocular Ortho-K lens from May 2012 to January 2017. The axial length (AL) of both eyes was recorded, and we calculated the AL difference as our primary outcome, to evaluate myopia progression. High anisometropia was defined as anisometropia more than 2.50D. The generalized estimating equations (GEE) model was used to assess the related risk factors. Results: A total number of 31 unilateral myopic patients were identified. The initial wearing age of the subjects was 12.32+/−3.07 years. In myopic eyes, the initial spherical equivalent was −2.73+/−0.95 diopter (D). The mean follow-up duration was 2.01+/−1.48 years. A significant reduction in the AL difference was found, from 0.83+/−0.45 millimeters at the baseline to 0.59+/−0.49 millimeters at 24 months (P = 0.039). Besides, after wearing Ortho-K lens for a long term, high anisometropic wearers showed more AL difference reduction than low anisometropic wearers in unilateral myopic children (P=0.002). Conclusion: This study demonstrated that the myopic eyes in unilateral myopic children had less AL growth than the companion emmetropic eyes when treated with monocular Ortho-K lenses. Wearing Ortho-K lens for a long time would present a more significant AL difference reduction in high anisometropic children. Keywords: Anisometropia, Axial length, Myopia control, Orthokeratology, Unilateral myopia