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What is Refractive Surgery?
Last updated on December 14, 2020 by Lasikon.de
Refractive surgery is a series of eye operations that change the refractive power of the eye. The term "refractive”Means:“concerning the refractive power". What is meant is of course the refractive power of the eye.
The human eye is (also) an optical system that consists of several optical components. These include the cornea, the lens of the eye, the aqueous humor and the vitreous humor. Each part has an important function.
The two most important components in terms of refractive power are the cornea and the lens of the eye:
- Cornea of the eye: approx. 75% of the optical effect
- Eye lens: approx. 25% of the optical effect
Therefore, refractive surgery focuses on these two parts. There are a number of surgical methods that differ with regard to ...
- the cost,
- the risks,
- the healing time,
- the pain
- of durability and
- possible side effects
differ from each other.
History of Refractive Surgery
Refractive surgery began in the early 20th century. The basic idea is to change the surface of the cornea - and thus its refractive power - so that one can see clearly again without visual aid. The first experiments to model the cornea were made in the 1930s. The first approach was to incise the cornea radially, i.e. from the center outwards, and thus to strengthen the curvature in the outer areas. The procedure was called radial caratotomy (after the Greek keras = Horn,keratoeides chitōn = Cornea), abbreviated “RK”.
The main problem with radial keratotomy was inaccuracy. You could never exactly predict how the cuts would actually develop and heal. The series of failures was correspondingly large, as it turned out a few months / years later (in the so-called PERK study). The process was therefore not developed any further.
In the early 1960s, the Spanish ophthalmologist Jose Iganacio Barraquer began a procedure in which the inner corneal layer is removed. This approach was called keratomileusis (after the Greek: Kerato = Cornea and Mileusis = Shaping). In the early years, however, the whole thing was done with a scalpel, i.e. a very fine knife. But you can imagine that it was very risky and error-prone. So the idea was born, the only thing missing was the instruments to be able to carry out such a fine operation safely and precisely.
- More about keratomileusis.
Photorefractive Keratectomy (PRK)
In 1983, the American eye surgeon Stephen L. Trokel came up with the idea of performing the procedure with a laser beam. Instead of a knife it was used as a laser. The procedure has been called photorefractive keratectomy (PRK). An excimer laser is a very fine gas laser that can generate electromagnetic radiation in the ultraviolet wavelength range. It took four years of research before the process was first applied to humans in 1987 at the University Hospital of the Free University of Berlin (by Theo Seiler).
On the cornea, the top layer (so-called epithelium) is completely scraped off in a circle of approx. 1 cm. The cornea is then processed with the laser. The healing process that follows takes several days / weeks and can be quite painful.
- More about photorefractive keratectomy.
LASEK (Laser Epithelial Keratomileusis)
In the 1990s, the PRK was further developed into the LASEK. LASEK differs in the way the upper corneal layer is removed: while it is completely destroyed in PRK, it is available as a wound dressing after the LASEK operation. The top layer is loosened with alcohol and carefully pushed aside with a knife. LASEK stands for Laser Epithelial Keratomileusis, which means something like: the surface of the cornea (epithelium) is processed with the help of a laser.
LASIK (laser in situ keratomileusis)
In 1989 the keratomileusis was combined with the excimer laser procedure for the first time and was named by Ioannis Pallikaris Laser in situ keratomileusis (LASIK). Exactly this procedure has proven itself - it is used today as the standard for laser eye surgery and is further developed or refined.
- Wikipedia: Refractive Surgery
- Wikipedia: Laser in situ keratomileusis
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