The laser produces a uniform, concentrated beam of high energy ultraviolet light that is precisely focused onto the cornea. During the procedure, the laser's light energy is converted into chemical energy which evaporates molecules of corneal tissue in very precise amounts. By altering the curvature of the cornea in this way, PRK helps reduce or eliminate moderate nearsightedness and astigmatism. Candidates for PRK should be at least 18 years old, have stable vision and no abnormalities of the cornea or external eye. This flattens the cornea and changes its focusing power so that light rays fall precisely on the retina.
Radial keratotomy is used to treat nearsightedness and some forms of astigmatism.
Candidates for RK should be at least 18 years old, have stable vision and no abnormalities of the cornea or external eye. In LTK, the doctor uses a laser to heat a series of small, dot-shaped areas of the cornea. This causes the corneal tissue to expand and the curvature of the cornea steepens. LTK is used to treat people who are farsighted. Candidates for LTK should be at least 18 years old, have stable vision and no abnormalities of the cornea or external eye.