Procedures like RK (radial keratotomy) and AK (astigmatic keratotomy) have been performed since the early 1970's to improve vision due to nearsightedness (myopia), farsightedness (hyperopia) and astigmatism. Called refractive surgery, these techniques have corrected or improved the vision of hundreds of thousands of people. General studies show that approximately 95% of patients with mild to moderate nearsightedness, who have refractive surgery are able to pass a standard driver's license eye exam (20/40 visual acuity or better) without wearing corrective lenses. Not everyone should expect to achieve full visual correction however. Some people, for example, may have significant improvement after surgery but still need corrective lenses for some activities. *A discusion with the surgeon will provide a better indication of expected results based on your individual needs and the specific technique used by the surgeon the improve your vision.
PRK changes the shape of the cornea of the eye so images are focused
correctly at the back of the eye. In nearsighted (myopia) people,
for example, the curvature of the cornea is too steep or the eye
is too long, causing light rays to focus in front of the retina
on the back of the eye.
After extensive pre-surgery testing, a computer is programmed by the doctor for each person's own correction factors. Next, in treating myopia, as shown in the animation above, the laser segment of the procedure starts with the patient laying on their back. A narrow laser beam is first applied. As the laser beam expands, a tiny lens shaped disc is created. The focal point of the beam only penetrates the cornea about two thousandths of an inch (about half the thickness of a human hair). Only a small area in the center of the cornea is treated, essentially producing a concave lens over the visual axis.
|PRK for nearsightedness reshapes the cornea by creating a concave disk on the surface of the cornea, effectively reducing its curvature, allowing distant images to focus.|
After laser surgery, the healing process replaces some of the tissue removed by the laser, and as a result the final outcome takes time to achieve. Most people are able to return to work within a few days of the procedure.
During the first week after surgery, while your eye heals and the surface cells of the eye smooth out, your vision will be blurred. As your eye heals, some improvement continues for a few months but most change takes place during the first week after surgery.
To be eligible for PRK the eye must be in good health and vision must be stable. However, some people are better candidates than others and consultation with the doctor prior to surgery is important to determine estimated benefits and possible complications.
PRK is performed on an outpatient basis. The procedure itself is painless, as a topical anesthetic is used to numb the eye prior to surgery. PRK normally takes less than 15 minutes and the patient leaves shortly after the procedure. An eye patch may be placed on the eye for temporary protection and to keep you from rubbing your eye in your sleep. Medication drops are used for pain relief, to prevent infection and promote healing.