Corneal change accompanying orthokeratology. Plastic or elastic? Results of a randomized controlled clinical trial

Effects of orthokeratology on refractive error, visual acuity, and corneal curvature were monitored on two randomized comparison groups for 364 days of lens wear and 95 days of follow-up after lens wear was discontinued. Approximately 36% of the treatment group compared with 13% of the control group had 1 diopter or more change in refractive error; however, after lens wear was discontinued, there was substantial remission and differences between the groups were small. Although there was a positive correlation between the amount of change during lens wear and the persistence of change after discontinuation, neither the magnitude of persistence nor differences between groups were clinically important. The lack of persistence indicates that the cornea is either highly elastic or has some other memory mechanism. We conclude that orthokeratology produces modest reductions in myopia; however, the effect will not persist without continued lens wear and therefore is of limited clinical value in permanently reducing myopia.