LASIK or Lasik (laser-assisted in situ keratomileusis), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and an actual cure for astigmatism, since it is in the cornea. LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity.
LASIK is very similar to another surgical corrective procedure, photorefractive keratectomy (PRK), and LASEK. All represent advances over radial keratotomy in the surgical treatment of refractive errors of vision. For patients with moderate to high myopia or thin corneas which cannot be treated with LASIK and PRK, the phakic intraocular lens is an alternative.
As of 2018, roughly 9.5 million Americans have had LASIK and, globally, between 1991 and 2016, more than 40 million procedures were performed. However, the procedure seemed to be a declining option as of 2015.
The planning and analysis of corneal reshaping techniques such as LASIK have been standardized by the American National Standards Institute, an approach based on the Alpins method of astigmatism analysis.
The FDA website on LASIK states,
"Before undergoing a refractive procedure, you should carefully weigh the risks and benefits based on your own personal value system, and try to avoid being influenced by friends that have had the procedure or doctors encouraging you to do so."
The procedure involves creating a thin flap on the eye, folding it to enable remodeling of the tissue beneath with a laser and repositioning the flap.
Patients wearing soft contact lenses are instructed to stop wearing them 5 to 21 days before surgery. One industry body recommends that patients wearing hard contact lenses should stop wearing them for a minimum of six weeks plus another six weeks for every three years the hard contacts have been worn.
The cornea is avascular because it must be transparent to function normally. Its cells absorb oxygen from the tear film.
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Refractive surgery is optional eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea (keratomileusis), lens implantation or lens replacement. The most common methods today use excimer lasers to reshape the curvature of the cornea. Refractive eye surgeries are used to treat common vision disorders such as myopia, hyperopia, presbyopia and astigmatism.
Keratoconus (KC) is a disorder of the eye that results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, irregular astigmatism, and light sensitivity leading to poor quality-of-life. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea. While the cause is unknown, it is believed to occur due to a combination of genetic, environmental, and hormonal factors.
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