What is refractive surgery?
Refractive surgery involves the use of lasers or other devices to treat the refractive errors of the eye. Radial keratotomy has been practiced in the United States for nearly 20 years, but it has now been surpassed by the use of the excimer laser for treating nearsightedness, farsightedness and astigmatism. A new laser, called the holmium:YAG laser, is now being studied for treatment of farsightedness. If you are nearsighted, with or without astigmatism, you may be a candidate for refractive surgery.
LASIK (laser in situ keratomileusis):
LASIK is an excimer laser surgical procedure that treats the middle layers of the cornea to correct nearsightedness, farsightedness, and/or astigmatism. LASIK is performed using numbing drops to help prevent pain during the procedure. A flap is created using the IntraLase, blade-free, all laser method. This flap is folded over, and the laser surgery is performed in the bed of the cornea that is exposed. The laser treatment reshapes the cornea to treat the refractive condition. The actual laser portion of the procedure lasts 10 to 90 seconds. The flap is then folded back into its original position and observed for 2-3 minutes to insure that it is fully adherent.
Advantages of LASIK include: 1) little or no discomfort following the surgery, 2) recovery of vision often within 1-2 days, 3) little or no risk of developing haze following treatment, and 4) ease of doing additional laser treatment should this be necessary. As with any surgical procedure, complications can occur, including those that could result in loss of vision. Fortunately, severe complications are extremely rare.
PRK (photorefractive keratectomy):
PRK uses the excimer laser to reshape the front surface of the cornea to change its focusing power. Surface cells of the cornea (the epithelium) are gently removed from the central portion of the cornea to expose the region of the cornea that is treated with the laser. The actual laser time is similar to that with LASIK.
The surface cells require two or more days to heal, and a soft contact lens is placed over the eye during this period to serve as a bandage.
PRK has been approved for treatment of nearsightedness up to 12 diopters with the VISX Star laser.
LTK (laser thermal keratoplasty):
LTK uses light from the holmium laser to heat the cornea in order to change its shape. A typical treatment consists of two rings, each containing eight spots, which are placed around the central zone of the cornea. By gently warming the cornea, these spots increase the focusing power of the cornea to treat the farsightedness. This laser has recently been FDA approved, and the only one available is the Sunrise Hyperion.
Intracorneal Ring Segments (Intacs):
Intracorneal Ring Segments use small polymethyl-methacrylate (PMMA, a type of clear plastic) to alter the front curvature of the cornea. These ring segments are placed within the substance of the cornea, and cause the central part of the cornea to change its shape. By flattening the central cornea, Intracorneal Ring Segments can be used to treat nearsightedness. They are limited for use in only patients with mild nearsightedness, and without significant astigmatism.