eye disorders
Surgery for Refractive Errors
Laser In Situ Keratomileusis (LASIK)
LASIK is used to correct nearsightedness, farsightedness, and astigmatism. In LASIK, a very thin flap is created in the central part of the cornea with a laser or a cutting device called a microkeratome. The flap is lifted, and computer-controlled pulses of highly focused ultraviolet light from an excimer laser vaporize tiny amounts of corneal tissue under the flap to reshape the cornea. The flap is then laid back in place and heals over several days. LASIK causes little discomfort during and after surgery. Vision improvement is rapid, and many people are able to go back to work within 1 to 3 days. Complications include possible flap-related problems and long-term thinning and bulging of the cornea (ectasia). If a flap problem develops during surgery, the surgery is stopped but sometimes may be tried again after about 6 months. Another flap problem is a flap dislocation, which usually occurs after a severe eye injury and causes blurry vision. This problem can often be fixed with immediate treatment. Very rarely, flap problems develop when, for example, a flap heals with ridges and causes blurring or Glare and Halos . If these flap problems cannot be corrected, they can permanently impair function (such as driving at night) unless a rigid contact lens is used. Ectasia can cause blurring, increased nearsightedness, and irregular astigmatism. Other complications include severe, intermittent blurring resulting from dry eyes and, rarely, vision-threatening infection or inflammation of the cornea. People who have any conditions that prevent them from having refractive surgery, as well as those who have thin corneas or a loose corneal surface layer, may not be good candidates for LASIK. 