The more severe a patient's nearsightedness, the less effective the corneal reshaping of RK will be in correcting the problem. RK patients who originally suffered from only mild nearsightedness may, if the cornea does not heal evenly, develop an astigmatism that requires corrective lenses. As the eye heals from an operation to correct nearsightedness, it may in fact overcorrect, causing the person to be farsighted. Those who choose to undergo RK tend to be as nearsighted before this operation as those who choose not to undergo RK.
Radial keratotomy (RK), a surgery that is designed to reshape the cornea so that light focuses correctly on the retina, is supposed to make eyeglasses or contact lenses that correct for nearsightedness unnecessary. Yet a study of patients who have undergone RK shows that some of them still need to wear glasses or contact lenses.
Each of the following, if true, would help to resolve the apparent discrepancy in the information above EXCEPT: