Understanding corneal morphological changes and influencing factors in myopic children after long term orthokeratology lens wear and 1-month of discontinuation

Background Orthokeratological (OK) lenses provide reliable daytime vision for myopic patients through a reverse geometry design, altering the central and peripheral corneal morphology. In this study, we aimed to investigate overall and regional corneal morphological changes in myopic children after long-term OK lens wear and 1-month cessation. Methods Forty-three myopic children (17 males, 26 females; mean age: 9.51 ± 1.44 years) who have been continuously wearing OK lenses for over 12 months participated in this study. Discontinuation of their lens wear for one month was arranged, followed by routine examinations, particularly corneal topography assessing the central and peripheral corneal morphology. Baseline topography records (before the initiation of orthokeratology lens treatment) of all patients were reviewed. The data after 1 month of discontinuation were compared to the baseline. Statistical analysis were performed using the paired t-test and Wilcoxon tests. Results Patients wore lenses for an average duration of 24.45 ± 8.72 months. Central corneal flat curvature decreased significantly, with increased astigmatism. In the peripheral corneal regions, the horizontal curvature became flatter, while the superior curvature became steeper. The height difference in the 8 mm chord length significantly increased. Segmental data analysis showed an increase in the astigmatism range above and an increase in corneal astigmatism symmetry above and below. Conclusion Peripheral corneal changes in horizontal meridians may lead to changes in the required lens alignment curve after long-term OK lens wear. Corneal astigmatism, combined with the change in the superior meridian, increased in magnitude, range, and symmetry. Patients with longer wear durations and greater baseline corneal height differences require closer attention due to the increased likelihood of corneal astigmatism post-discontinuation and potential changes in subsequent fittings.