PRK

Nearsightedness, farsightedness, and astigmatism can also be corrected by Photo-Refractive Keratotomy (PRK). Unlike LASIK, no corneal flap is created. The treatment is done on the surface of the cornea. Because no flap is created, this procedure may be ideal for individuals with slightly thin corneas or with specific corneal scars. The most common use is for the correction of nearsightedness. Nearsightedness occurs when the cornea is too curved or the eye is too long. This causes light to focus in front of the retina, rather than on the retina, resulting in blurry distance vision. PRK treats nearsightedness by removing corneal tissue from the surface of the cornea, causing the central optical zone to flatten. This allows light rays to focus more directly on the retina, thereby reducing nearsightedness.

The procedure is done using eye drop anesthesia. First, the corneal epithelium, a thin layer of cells on the surface of the cornea, is removed. Then, the computer controlled precision of the Excimer laser is applied to remove a predetermined amount of corneal tissue. Because an epithelial abrasion the size of the treatment zone is created, a bandage contact lense is placed on the cornea immediately after treatment. The amount of tissue to be removed is determined by the amount of nearsightedness, farsightedness, or astigmatism to be corrected. For most patients, only five to ten percent of cornea is removed to obtain the desired result. As healing occurs, the epithelium regrows and covers the area of laser treatment. The contact lens is removed in 48 to 72 hours.

Although the vast majority of patients see 20/40 or better postoperatively, individual results cannot be guaranteed. Patients over 40 years old may find they need glasses for close vision after surgery. The surgery is performed on an out-patient basis and most people return to work within one to three days. As with any surgical procedure, side effects and complications may occur.