What is ortho keratotomy or orthokeratology?
Ortho keratotomy should actually be called orthokeratology. Keratotomy actually refers to a type of eye surgery, the most common of which is radial keratotomy, which is a corrective surgical procedure for vision that predates PRK and LASIK.
Orthokeratology is a non-surgical technique that involves the wear of corrective contact lenses while sleeping. The lenses reshape the eye's cornea in order to correct vision. The lenses must be custom made based on the individual's eye shape. An eye doctor will determine the "ideal" corneal shape for correct vision. Orthokeratology is the process of creating contact lenses which reshape the cornea to that "ideal" shape, thereby correcting vision (American Academy of Orthokeratology and Myopia Control).
The cornea's overall thickness is measured in microns, or thousandths of a millimeter. It's about half a millimeter in overall thickness. The doctor will prescribe a wearing schedule for the customized contact lenses which will allow the corneal layer to slowly adjust its shape to the contact lens. Because the cornea is so thin, it changes after relatively few sessions of wearing the lenses. But as the cells of the cornea realign and redistribute along the surface and change its strength and thickness in various areas, they can also return to their original distribution. Thus, orthokeratology requires the user to continue wearing their corrective lenses semi-regularly after the initial course of wearing. The initial course of wearing might be several days or weeks long, and maintenance sessions may be for several hours per day, for a few days per week. An eye doctor will prescribe an exact amount of time.
Orthokeratology is also called ortho-k. Doctors may prescribe the procedure to patients who meet certain criteria such as limited vision correction needs and astigmatism. It is also only for patients with myopia, or nearsightedness.