PRK is an option for those patients have corneas too thin for LASIK or have large pupils. The primary difference between PRK and LADIK is that the surface of the cornea is treated with PRK while the inner tissue of the cornea is treated with LASIK. Both have similar success rates, but LASIK offers patients less postoperative discomfort and quicker return to functional vision. Most PRK patients notice an improvement in their vision soon after surgery, however, vision is usually somewhat blurred during the epithelial healing process. Many PRK patients prefer to have one eye treated at a time with the second eye being treated within a week to two.
Both LASIK and PRK reshape the cornea to the correct focusing power. Below describes how Nearsightedness, Farsightedness and Astigmatism are corrected.
Nearsightedness
If the cornea is too steep or the eye is too long, the laser must remove tissue from the center of the cornea to reduce its focusing power. This moves the point of the focus from in front of the retina to on the retina.
Astigmatism
If the cornea is more curved in one direction than the other, the laser must remove the tissue so that the cornea is more symmetrical. This eliminates multiple focal points and establishes one point of focus on the retina.
Farsightedness
If the cornea is too flat or the eye is too short, the laser must remove tissue from the outer zone of the cornea to make it steeper and increase its focusing power. This moves the point of focus from behind the retina to on the retina.
