The LASIK, (laser in situ keratomileusis), process has been used for ten years now, to treat myopia, hyperopia and astigmatism. In 1995, with the approval of PRK, the procedure became more widely available in the United States as an off-label use of the excimer laser.
In this procedure, the surgeon cuts a hinged corneal flap composed of the outermost 20-25 percent of the cornea’s thickness. The computer-controlled excimer laser then reshapes the underlying exposed cornea. This minimizes discomfort and promotes rapid recovery. The surgeon then puts the flap back into place.
LASIK resembles PRK in that both procedures use the excimer laser to change the refractive error. However, because the surgeon creates the flap, LASIK preserves the epithelium and outermost stroma (the outermost 20-25 percent of the thickness of the cornea). As a result, the surface of eyes treated with LASIK heals faster than those treated with PRK. Most patients achieve good vision the day following surgery. Furthermore, patients experience less discomfort. LASIK requires more instrumentation than PRK, and additional surgical precision is necessary to handle the microkeratome.
LASIK is a surgical procedure, and like all surgeries, it possesses the potential for risks and complications. The following information provides you with an understanding of the risks so you can make an informed decision. Every patient should weigh the chance of experiencing complications against the potential benefits LASIK can afford.
Numerous studies demonstrate that the incidence of corneal haze is significantly lower with LASIK than with PRK. Corneal haze – what the doctor sees under the slit lamp – results from the superficial cornea’s healing reaction after contact with a laser. An ophthalmologist can measure the haze response of a patient’s cornea under a slit lamp, but patients’ experiences of haze vary.
Corneal haze should not be confused with "hazy vision" that some patients may experience at night or in dim light. Decreased night or low-light vision is characterized by symptoms such as glare, halos and starbursts that are seen around objects at night or in dim-light conditions.
Other risks reported in studies prior to 1995 include corneal damage leading to permanent corneal scarring or swelling, droopy eyelid, contact lens intolerance and persistent discomfort. The majority of complications recorded in the early studies were intra-operative. As microkeratome technology has improved, the incidence of these LASIK complications has diminished. Researchers expect further reductions as instrumentation becomes more sophisticated.