Orthokeratology (ortho-K, corneal refractive therapy) is a non-surgical alternative to laser surgery for vision correction. It involves the prescribed use of contact lenses to remould the surface of the cornea to correct myopic (short-sighted) and astigmatic (irregular surface) errors that would otherwise require glasses.
They are worn only during sleeping hours to give clear vision without the need for contact lenses or spectacles for the majority of, or possibly for all, waking hours.
Ortho-K works best with myopia up to -4.00 dioptres and astigmatism up to -1.50 dioptres. There are options for higher prescriptions but is not always successful. The effect of orthokeratology is temporary and for refractive stability, the contact lenses are best worn on consecutive nights, ongoing.
During the process of wearing the contact lenses the epithelium, the outer-most layer of the cornea, is the only layer of the cornea that is altered. The contact lens sits on a thin layer of tears and generates forces that gradually create a new corneal shape. The corneal epithelium is renewed every 14 days throughout life so the process of ortho-K is completely reversible.
Historically, optometrists have accepted that myopia in some children will get progressively worse over their teenage years and even into their 20s. Now, with advances in vision correction, orthokeratology has gained momentum in several fields of research including the control of myopia progression.
There is a growing body of evidence that orthokeratology can be used to slow the rate of myopia progression (myopia control). The therapy is only suitable at the discretion of your practicing optometrist as other intervention strategies may be indicated.
Ortho K is also useful for people who participate in sports, or who work in dusty, dirty environments that can cause problems for regular contact lenses.
The process of orthokeratology starts with a comprehensive eye exam to identify the factors involved. From there, images of the cornea are taken with a topographer, which gives an accurate picture of the curvature of the cornea. From here, the ortho-K contact lenses are customised and ordered for the fitting process to begin.