Refractive Surgery
Refractive Surgery is a term for several procedures designed to treat 'refractive errors' such as nearsightedness, farsightedness, and astigmatism.

• LASIK
  Laser in-situ keratomileusis, or LASIK, is a surgical procedure that is able to correct a wide range of nearsightedness (myopia), farsightedness (hyperopia) and astigmatism.
  
  
• LASEK
  LASEK is a modification of the PRK and LASIK procedures.
  
  
• PRK
  PRK (photorefractive keratectomy), a refractive eye surgery, is similar to LASIK in that both procedures employ a computer-controlled excimer laser to reshape the cornea (the front surface of the eye), in order to change its ability to focus light on the retina of the affected eye.
  
  

The following porcedures were how refractive sugery began, however, are rarely used now due to advances in technology.

• Radial Keratotomy (RK) - was the first widley accepted procedure that surgically corrected low to moderate levels of nearsightedness. It was first attempted in the 1970s by a Russian physician. He discovered that placing a number of microscopic, spoke like incisions, in a radial pattern around the center of the cornea caused it to flatten. This flattened shape allows light to focus more directly on the retina, thereby reducing or eliminating nearsightedness.
  
  
• Astigmatic Keratotomy (AK) - is simply a modification of the Radial Keratotomy technique for patients who have nearsightedness and astigmatism. To treat astigmatism, the cornea must be made more spherical, or uniformly curved in all directions. This is accomplished by making incisions in the steepest part of the cornea, causing it to relax and become more round. AK can be performed along with other types of refractive surgery too.