A sample of slow and fast progressors in prior 24 month orthokeratology clinical trials were found to have the same baseline refraction and axial length. The slow progressors were older, and showed 0.5mm smaller treatment zone diameters (TZDs), but no difference in induced peripheral myopic shift. There was also no direct correlation between TZD and axial elongation, indicating an intriguing but not yet defined relationship.
This study evaluates how orthok treatment zone diameter influences change in refraction and axial eye length over 1-year in children previously fit with orthok lenses of varying back optic zone diameter, to reveal that where treatment zone diameter was less than pupil diameter orthok’s myopia control efficacy appeared to be improved.
Soft contact lenses designed to simulate the change in refraction optical pro-file from orthokeratology (OK) fail to slow axial eye elongation or change to refrac-tion over 1-year of wear in children, leading to suggestion that OK’s propensity to slow myopia progression may not be due to changes OK makes to optical profile.