There are various types of laser eyesight correction available, allowing those with poor vision to improve it with an operation that can usually reshape the cornea within a few minutes. One of the most popular kinds is LASIK, which reshapes the middle of the cornea so that light is focused better, resulting in improved vision with no pain. This surgery requires that a flap be cut in the outer cornea so that it can be removed, reshaped, and put back. LASEK, on the other hand, involves dissolving the cornea completely with chemicals. Similarly, PRK involves the removal of the cornea, but without a chemical solution, making it the more painful option in general.
LASIK is an acronym for laser-assisted in situ keratomileusis, which treats those who are nearsighted, farsighted, or afflicted with astigmatism. In this popular surgery, the middle of the cornea, called the stroma, is removed through a flap in the outer cornea, called the epithelium. The stroma is then reshaped with a laser and put back into place, allowing the flap in the outer cornea to be closed afterward so that it can heal. This type of laser eyesight correction is typically painless, but it is not usually recommended for those with dry eyes, large pupils, or thin corneas.
Those who cannot get LASIK for medical reasons may opt instead for LASEK, or laser epithelial keratomileusis. This laser eyesight correction surgery requires that the entire outer layer of the cornea be removed using a chemical solution that helps dissolve it, making it easy to remove without cutting into it. Once the epithelium is gone, the stroma can be easily accessed and reshaped with the laser. Fortunately, the epithelium grows back eventually, so a soft contact lens is usually placed over the eye to protect it until this happens.
Another common type of laser eyesight correction is called PRK, or photorefractive keratectomy. Like LASEK, no flap is made in the cornea to access the stroma. Instead, the epithelium is removed, but it is cut off by the surgeon instead of dissolved with chemicals. The recovery period is typically longer with this kind of laser eyesight correction, and it is usually more painful than the other types, but it is also usually less expensive. Additionally, unlike LASIK, this procedure lacks the chance of issues arising with the healing epithelium years after surgery since the outer layer of the cornea typically grows back fine.