Ortho-k is a technique in which semi-rigid contact lenses are weared at night. These cause a temporary change in the curvature of the cornea. The effect sought is that during the day the person sees clear without the need of contact lenses or lenses.
It began to be studied in the early 60's of the last century, but when more strength it has taken since the 90s, inventive designs of reverse geometry (the desired effect is achieved in a few days) and that combined with materials of high permeability in the oxygen has allowed to perform night-time nocturnal with safety.
It has been widely used in myopia, but designs have now appeared for people with hyperopia, astigmatism or even with presbyopia. Also, it is highly appreciated for athletes, for jobs in which there is a lot of dust or even for those who have ocular dryness and can no longer use the usual contact lenses.
It is a reversible method. When they leave, after a few days, it returns to the original refractive state.
In recent years, it has been discovered that in those myopic young people, who are increasing their myopia, these ortho-k lenses are used to control this increase. In many cases, the reduction of the increase may be 50% or more depending on the cases.