Corneal Refractive Therapy or CRT is a non-surgical procedure involving wearing specialized contact lenses while sleeping. The contact lenses reshape the cornea so that the patient sees well without contact lenses or glasses during the day. It is intended mainly for mild to moderately nearsighted patients who may also have small amounts of astigmatism.
Corneal refractive therapy is a procedure principally used to help control nearsightedness (myopia) and certain amounts of astigmatism. In myopia and astigmatism, the light entering the eye does not focus directly on the macula. Glasses or normal contact lenses - whether they are soft or gas permeable (GP) - correct the path of the light. Once these are removed, vision becomes blurry again.
Corneal refractive therapy contact lenses are designed differently and fitted differently than regular contact lenses. This procedure uses a special contact lens design called "reverse geometry" to change the shape of the front surface of the eye, the cornea. These special contact lenses are worn only at night when a patient sleeps. Overnight, the contact lenses reshape the cornea so that when the lenses are taken off the next morning, a patient's vision is clear. This new shape enables the patient to see well without wearing contact lenses or glasses.
For most patients, vision will remain clear the whole day without any need for glasses or contact lenses. Most people need to wear their corneal refractive therapy contact lenses every night or every other night to keep the cornea in the proper shape. Some patients may need occasional daytime glasses or contact lenses for certain tasks, like extensive reading.