PRK

PRK (Photorefractive Keratectomy) is laser eye surgery that treats nearsightedness, mild to moderate farsightedness and astigmatism.

PRK used to be the most common refractive surgery procedure before LASIK. Both are grouped under the umbrella "laser eye surgery," but each is a little different when it comes to advantages and disadvantages. LASIK patients have less discomfort and obtain good vision more quickly (with PRK improvement is gradual and over a few days or even months), but many surgeons prefer PRK for patients with larger pupils or thin corneas.

PRK is performed with an excimer laser, which uses a cool ultraviolet light beam to precisely remove ("ablate") very tiny bits of tissue from the surface of the cornea in order to reshape it. When you reshape the cornea in the right way, it works better to focus light into the eye and onto the retina, providing clearer vision than before.

Both nearsighted and farsighted people can benefit from PRK. With nearsighted people, the goal is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. Also, excimer lasers can correct astigmatism, by smoothing an irregular cornea into a more normal shape.

Your doctor will examine your eyes to determine exactly what kind of vision correction you need and how much laser ablation is needed. A corneal topographer will be used; this is an instrument that photographs your eye and creates a kind of "map" of your cornea. No one has a perfectly rounded cornea, and the topographer will display the corneal irregularities and the actual steepness or flatness that the surgeon must address.

PRK is an ambulatory procedure; you walk into the surgery center, have PRK, and walk out again. In fact, the actual surgery usually takes less than a minute, and you're awake the whole time. Occasionally, the doctor will give a mild oral sedative beforehand.

Most people don't feel pain during PRK. Your eyes are first anaesthetised with special drops. The doctor will have you lie down, then make sure your eye is positioned directly under the laser. (One eye is operated on at a time.) A kind of retainer is placed over your eye to keep your eyelids open — normally, this is not uncomfortable. It has a suction ring that keeps your eye pressurised and immobile.

The doctor uses a computer to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while he or she watches your eye through a microscope to make sure it remains in the correct position while the laser sends pulses of light to your cornea that painlessly remove the tissue. It's important to keep your gaze fixated on that target light in order to get the best results.

The higher your prescription, the more time the surgery will take.

The doctor may prescribe medication for any postoperative pain, but many people feel no more than mild discomfort or "scratchiness" afterward.

Immediately after PRK, the doctor will have you rest for a bit, then you can go home (someone else must drive). At home, you should relax for at least a few hours.

Most people achieve 20/20 or better vision with PRK (also true of LASIK). Some may achieve only 20/40 or not quite as good. In fact, 20/40 is fairly good vision. Some patients may still need glasses or contact lenses following laser vision correction, though their prescription level will be much lower than before.

Please ask your doctor for further information.