Refractive surgery includes an array of modern surgical procedures designed to improve vision problems, often eliminating the need for corrective lenses. Glasses or contact lenses can correct most vision problems; however, when these are not the most practical solutions, refractive surgery should be considered an effective alternative for improving vision. PRK and LASIK are the most common methods of refractive surgery today.They use excimer lasers, the most technologically advanced method of corrective surgery, to reshape curvature of the cornea.The excimer laser is a charged mixture of argon and fluoride gases in a mirrored tube to produce a beam of ultraviolet light. This beam is unique because it has the ability to break the molecular bonds between tissue and vaporize tissue, a microscopic layer at a time. The laser can sculpt tissue with no effect on the underlying and surrounding tissue. This makes it ideal for changing the shape of the cornea, the eye's front window, to reduce or eliminate focusing problems. Successful refractive eye surgery can reduce or cure common vision disorders such as myopia(nearsightedness), hyperopia (farsightedness) and astigmatism.