How is orthokeratology (Ortho-K) used for myopia control?

Orthokeratology lenses, which are customized contact lens molds, are worn each night and removed each morning. The molding that occurs overnight allows for clear vision at all distances during the day without glasses or daytime contact lenses. The lenses are comfortable and do not interfere with sleep. They last approximately a year and are worn as long as myopia progression is considered a risk or until freedom from daytime lens correction is no longer desired. Further information, including a search engine to find doctors fitting the lenses, can be found at

How does Ortho-K work for myopia control?

It generally works very well. Of all the optical solutions that have been studied in controlled clinical trials, Ortho-K has been shown to slow myopic progression the most. It is thought that the control occurs due to the lenses creating what is called peripheral myopia. You can read about peripheral myopia in the definitions menu.

Clinical trials (which can be found in the Research menu under Orthokeratology (Ortho-K) have reported slowing myopia 55% to 100%. Retrospective case studies, a less stringent study design, have show high rates of prevention. The following chart is from a study by Wilcox and Bartels.

CANDY study

The blue line represents those patients not wearing Ortho-K lenses whose myopia progressed (the line slopes upward) and the red line represents those patients wearing Ortho-K lenses whose myopia was stabilized.

Are there any side effects?

The biggest side effect of controlling myopia with Ortho-K lenses is actually a benefit, namely there are no lenses to be worn during the day during which time vision remains clear. The greatest potential adverse risk for any contact lens patient is infection. There have been some reports of increased risk of infection with Ortho-K lenses but nearly all the reports were from a time approximately 10 years ago in Asia when the fitting of the lenses was largely unregulated.

What are orthokeratology (ortho-k) lenses?

Ortho-K lenses are specialized, customized molds that look like large, rigid gas permeable (RGP) contact lenses. They are approximately the size of the colored part of the eye (iris). They are applied each night and removed each morning. You can learn more about them in the Definitions menu under Ortho-K (Orthokeratology).

Here are a few pictures of orthokeratology lenses from their patents (linked images).

What are ortho-k lenses normally used for?

Ortho-K is normally used to allow a myopic person to have clear vision during the day without the need for corrective lenses. The effect is not permanent. If lens wear is stopped, the myopia will return. As a safe alternative to Lasik or other refractive surgery procedures that are not even available for children, Ortho-K is a viable alternative for vision correction for both children and adults. See for more information.