Overnight vision correction, also known as orthokeratology, OrthoK or corneal reshaping, is a procedure where you are fitted with specially designed rigid gas-permeable (RGP) lenses that you wear overnight. These lenses help to alter the shape of your cornea while you sleep in order to temporarily reduce or correct mild myopia (short-sightedness) or a low degree of astigmatism. After wearing the lenses, you should be able to see without glasses or contact lenses for a day or two, sometimes longer. For best results, you should wear the lenses every night.
Ask your optometrist for more information and for the College of Optometrists’ information sheet on orthokeratology.