Assessment of Corneal Biomechanical Changes After Discontinuation of Long-Term Orthokeratology: A 2-Year Prospective Study.

Purpose: This study investigated the long-term changes in the corneal biomechanical properties (CBPs) during and shortly after orthokeratology (ortho-k). We further explored the associations between selected CBPs and the effectiveness of ortho-k in mitigating axial elongation in patients with myopia. Methods: This prospective 25-month follow-up study included children ages 8 to 16 years with low to moderate myopia undergoing ortho-k treatment. They underwent 24 months of ortho-k followed by 1-month discontinuation. Their ocular biometric parameters and CBPs were monitored throughout the study. Axial length was measured at baseline, at 1 month, and then every 6 months after ortho-k treatment. Results: Dynamic changes in CBPs were observed during the 24-month ortho-k treatment. Parameters such as the stiffness parameter at the first applanation time (SP-A1), biomechanically corrected intraocular pressure, and Ambrósio's relational horizontal thickness showed initial reductions. After the 1-month discontinuation, most CBPs returned to baseline levels, except biomechanically corrected intraocular pressure and SP-A1. Multiple linear regression analysis revealed that differences in the deformation amplitude ratio or SP-A1 during the initial 2 weeks independently predicted axial elongation at 1 and 2 years after treatment initiation. Conclusions: Long-term ortho-k treatment may lead to sequential variations in CBPs; however, most of these variations may be reversed within 1 month of discontinuation. Further, changes in the deformation amplitude ratio or SP-A1 values during the early stages of treatment may predict subsequent axial elongation. Translational Relevance: This study highlights the value of corneal biomechanics in guiding myopia control during orthokeratology treatment in clinical practice.