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.
The first theoretical work on the potential of refractive surgery was published in 1885 by Hjalmar August Schiøtz, an ophthalmologist from Norway. In 1930, the Japanese ophthalmologist Tsutomu Sato made the first attempts at performing this kind of surgery, hoping to correct the vision of military pilots. His approach was to make radial cuts in the cornea, correcting effects by up to 6 diopters. The procedure unfortunately produced a high rate of corneal degeneration, however, and was soon rejected by the medical community.
The first proficient refractive surgery technique was developed in the Barraquer ophthalmologic clinic (Bogotá, Colombia), in 1963, by Jose Barraquer. His technique, called keratomileusis, meaning corneal reshaping (from Greek κέρας (kéras: horn) and σμίλευσις (smileusis: carving)), enabled the correction, not only of myopia, but also of hyperopia. It involves removing a corneal layer, freezing it so that it could be manually sculpted into the required shape, and finally reimplanting the reshaped layer into the eye. In 1980, Swinger performed first keratomileusis surgery in US. In 1985, Krumeich and Swinger introduced non-freeze keratomileusis technique, it remained a relatively imprecise technique.
In 1974 a refractive procedure called Radial Keratotomy (RK) was developed in the USSR by Svyatoslav Fyodorov and later introduced to the United States. RK involves making a number of cuts in the cornea to change its shape and correct refractive errors. The incisions are made with a diamond knife.
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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.
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.
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at night. Astigmatism often occurs at birth and can change or develop later in life. If it occurs in early life and is left untreated, it may result in amblyopia. The cause of astigmatism is unclear; however, it is believed to be partly related to genetic factors.
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