Orthokeratology - Ortho K
Ortho-K involves a procedure wherein you are required to wear special contact lenses, while you are sleeping. These special contact lenses gently reshape the surface of your eye, so you can see clearly even after you remove the lenses.
Myopia or nearsightedness is typically caused when light entering the eye is unable to focus properly on the retina. This problem of refocusing light rays is usually corrected by using eyeglasses or regular contact lenses worn daily.
Another way to achieve the same result is through surgery as in the form of LASIK. Ortho-k contact lenses flatten your cornea without surgery, enabling light to focus correctly on your retina, resulting in better vision.
The effect of Ortho-k is of course temporary and will typically get you through the day. These lenses will have to be worn again in the night to ensure the same effect the next day. Read more on uses of contact lenses.