Since nearsightedness, farsightedness and astigmatism are caused by anatomical factors (too long, too short, or distortion) for most people the best way to overcome or improve their focusing abilities is to surgically alter the shape of the cornea. This is preferable to more invasive procedures because it does not involve entering the eye and because the cornea is so accessible.

For many years, since the mid 1970's, radial keratotomy (RK) and astigmatic keratotomy (AK) were the only techniques readily available to change the shape of the cornea. By use of controlled incisions on the cornea, low amounts of nearsightedness and astigmatism could be corrected. People needing moderate to high ranges of correction were left without a reliable solution until the advent of advanced laser surgery. Not only is radial keratotomy limited in its effectiveness but fluctuations in vision may occur after the surgery because the incisions penetrate 90% of the cornea, which can cause weakness of the lens.