The actual laser part of the procedure takes twenty to ninety seconds. At the end of the procedure, a clear-bandage contact lens is placed over your eye to help keep you comfortable while the corneal epithelium regenerates (usually three to five days).
A typical PRK procedure takes about three to five minutes per eye. Operating on just one eye, or both eyes on the same day, is a decision to be made by the patient after discussing the pros and cons with the surgeon. Because the return of functional vision is prolonged under PRK, most surgeons prefer to wait at least one week before operating on the second eye.
Patients with certain corneal problems, such as an irregular corneal surface or a thin cornea, may be better candidates for PRK than for LASIK. The ultimate visual results are similar with PRK, although the recovery is somewhat prolonged in comparison.
One advantage of PRK over LASIK is that there is no risk of flap complications since no corneal flap is created. However, other potential complications of PRK are similar to those of LASIK. They include undercorrection, overcorrection, induced astigmatism, dry eye, haze, night glare and halos, loss of best corrected vision, infection or severe inflammation, and regression. Other disadvantages of PRK include the need for anti-inflammatory eye-drops for three months and the risk of corneal haze or scarring.
Regression occurs when a patient appears to be adequately treated on the first few postoperative visits, but over the next several weeks to months begins to return toward the original prescription. The amount of regression is usually small; however, occasionally it is visually significant and requires an enhancement procedure. The enhancement procedure is usually performed six to nine months after the original procedure. The time period before the return of optimal vision is significantly longer than with an enhancement after LASIK.
Intacs Corneal Ring Segments: Approved by the FDA in April 1999, Intacs corneal ring segments offer patients with mild myopia and minimal astigmatism another option for correcting their nearsightedness. Currently, the rings are approved for correction of nearsightedness up to 3.00 diopters in patients twenty-one years or older who have no more than 1.00 diopter of astigmatism. This procedure does not correct astigmatism. Patients who have astigmatism - even less than 1.00 diopter - need to understand they will be astigmatic postoperatively. Intacs are newer than LASIK and PRK, so they don't yet have a track record like the other two procedures.
With Intacs, two small plastic ring segments are inserted in the peripheral cornea through small incisional channels. A temporary suture is then used to close the incision. The rings cause the central cornea to flatten. The rings are intended to be permanent, but they may be removed if the patient wishes to reverse the correction. In clinical trials, when the rings were removed, many patients' eyes went back to their preoperative state. In some patients, they did not. Because some patients' eyes did not return exactly to their preoperative condition, the PDA will not allow the use of the term reversible, but Intacs are certainly removable if desired.
Intacs insertion takes slightly longer than LASIK, roughly fifteen minutes per eye under anesthetic drops. The recovery of clear vision takes slightly longer than LASIK. In addition, patients tend to experience more postoperative discomfort.
The cost of Intacs is roughly equal to, or more than, LASIK in most centers. Removal of the rings, either for fine-tuning the result or from dissatisfaction, is accomplished with a second surgery. The segments are removed, the eyes are allowed to heal, and an alternate procedure (such as LASIK, PRK, or a change in ring size) may be performed once the eyes have healed. The treatment range for Intacs is currently very limited.
Radial Keratotomy (RK): Until excimer lasers became available, radial keratotomy (RK) was the most commonly performed refractive procedure for nearsighted patients. With the aid of a high-powered microscope, the surgeon makes a series of radial microscopic incisions (usually between four and eight) on the surface of the cornea to reduce its curvature. This procedure was well suited for patients with low myopia and has been used for over twenty-five years. One form of RK, mini-RK, is still used occasionally for very minute degrees of nearsightedness, such as those resulting from slight undercorrections in LASIK or following cataract or clear lens extraction surgery.
Although outdated by excimer laser techniques, RK is still an effective procedure. It is used in those areas of the world that do not have access to the much more expensive laser technologies.
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