LASIK eye surgery is the best known of the laser treatments designed to correct common focal problems. However, PRK surgery is an alternative choice and has some advantages over LASIK.
PRK is an acronym for Photorefractive keratectomy. To understand the difference between these two, we need a brief examination of LASIK eye surgery. LASIK surgery is very quick and precise. The surgeon cuts a flap of tissue in the cornea approximately 100 to 180 microns or micrometers thick (.001 mm!). The excimer laser is then used to reshape the cornea to correct the problems of farsighted vision, nearsighted vision, as well as astigmatism. The sculpting is done below the nerve endings in the cornea so the procedure is relatively pain-free. Glasses are often put in a drawer after 24 hours and full healing is expected in one to three months. The natural pressure of the eye keeps the flap in place without the need for stitches.
This flap, however, has been known to cause problems with LASIK surgery in about 1% of the patients. Hazy vision and/or a dislocated flap are two other common problems. The LASIK surgery might also miss the exact center of vision thus causing double vision.
PRK, on the other hand, also involves sculpting the cornea but without cutting a flap. Instead of a flap, the outer layer (the epithelial layer) in the front of the cornea is removed. The sculpting is then done to the cornea just below this removed layer. This eliminates the problems associated with the flap. However, PRK surgery will be more painful since most of the pain receptors are in this removed surface layer of the cornea. This also means that a longer recovery time should be expected. Three to four months is common. A contact lens is placed on the eyeball for two to five days after surgery to protect the cornea as it begins to heal and regenerate.
Some people have a very thin cornea so that cutting the flap with LASIK is not possible. However, the shallower PRK surgery might accomplish the goal. This does not mean that everyone qualifies for PRK laser surgery. It is especially helpful for nearsighted people. The patient must be at least 18 years old, have a stable refraction error (eyes aren’t changing), and must be free of diseases such as glaucoma, vascular disease, diabetes and rheumatoid arthritis.
Though PRK patients do not face the flap problems, other risks should be considered. The most common complication for PRK and, in fact, all laser eye surgeries is dry eyes. The needed lubricating tears just stop being produced. Other people complain of glare, wrong correction, halos, reduced ability to see in low light, or chromic pain. One to three percent of patients on an average have worse vision following surgery than they had before it.
To know if PRK surgery is right for you, consult an optometrist or ophthalmologist who is trained in these procedures. Risk is a factor in all surgeries but now, after thousands of successful PRK procedures, the risk seems to be small.