Orthokeratology (ortho-k) is the fitting of specially designed gas permeable contact lenses that you wear overnight. While you are asleep, the lenses gently reshape the front surface of your eye (cornea) so you can see clearly the following day after you remove the lenses when you wake up.
Ortho-k lenses are prescribed for two purposes:
To correct refractive errors (primarily nearsightedness, but also astigmatism and hyperopia). In some cases, ortho-k also is used to correct presbyopia.
To slow the progression of childhood myopia. (Read more about myopia control.)
Ortho-k lenses are also called "corneal reshaping contact lenses" or "overnight contact lenses to correct or control myopia."
One specific brand of ortho-k lenses and fitting technique is Bausch + Lomb's Vision Shaping Treatment (VST). But ortho-k can be safely and successfully performed with other gas permeable (GP) lenses and corneal reshaping fitting techniques.
Only highly "breathable" GP lenses that have been FDA approved for overnight wear should be used for orthokeratology.