If an object is not sharply projected on the retina under standard conditions, there is a refractive error and the ophthalmologist speaks of an ametropia. If the reason for this is an eyeball that is too short or too long, it is an axial parametropy, whereby myopia (short-sightedness) is understood to be an eyeball that is too long in relation to the refractive power and hypermetropia (farsightedness) is understood to be an eyeball that is too short.
If the light is refracted too strongly or too weakly at the lens or cornea, this is referred to as refraction parametropy. If the cornea is not curved in the normal spherical shape, the result is a curvature of the cornea. Cataract is a clouding of the lens.
Experts for refractive surgery treat, among other things, the following ametropia or eye diseases:
- Nearsightedness (myopia)
- Long-sightedness (hyperopia, hypermetropia)
- Presbyopia (presbyopia, presbyopia)
- Corneal curvature (astigmatism, astigmatism)
- Keratoconus (change in the cornea of the eye)
Every ophthalmological examination includes questioning the patient about complaints or eye diseases that occur in the family. Visual acuity can be checked using visual charts.
Refractometry and skiascopy are available for objective refraction determination. In refractometry, a figure is projected onto the patient's retina and lenses are inserted into the beam path (either automatically by computer or manually) until the figure is sharp. In skiascopy, the type of ametropia can be determined by observing light reflexes on the retina. With subjective refraction determination, questions are asked as to which lens gives a better visual impression.
The surgical correction procedures can be assigned to either refractive corneal surgery or refractive lens surgery. In the first case, surgical changes are made to the cornea, in the second to the lens.
Procedures of refractive corneal surgery:
- In photorefractive keratectomy (PRK), the cornea is removed with an excimer laser either in layers (to correct myopia), only on the edge (to correct farsightedness) or ovally (to correct corneal curvature).
- With the procedures LASEK (laser-subepithelial keratomileusis) and Epi-LASEK, the surface of the cornea is also treated with the excimer laser in such a way that the defective vision is compensated.
- In LASIK (laser in situ keratomileusis), on the other hand, part of the cornea is first partially cut off and folded back, then the inside of the cornea is abraded with a laser and then the folded back cornea is folded back again. The modern form of LASIK is Femto-LASIK, also known as "laser-LASIK" or "gentle LASIK".
- In refractive lenticular extraction (RELEX), the cornea is only treated with a femtosecond laser (therefore also called FLEX or femtosecond laser lenticular extraction). A special method is SMILE.
- Further procedures are the astigmatic keratotomy and the limbal relaxing incisions (LRI), the implantation of ring segments into the outer cornea (intracorneal ring segments) and corneal cross-linking.
Procedures of refractive lens surgery:
- During the implantation of phakic (additional) intraocular lenses (Phake IOL, PIOL), the natural lens is supplemented by an additional artificial lens.
- In refractive lens replacement (RLA), the natural eye lens is replaced by an artificial lens.
Experts in refractive surgery are specialists in ophthalmology with special experience in the field of eye surgery. In the course of their specialist training and their professional activities, they have learned to recognise refractive errors and to treat them with the help of standard and latest procedures. In addition, these eye surgeons also have special surgical skills in refractive surgery.
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- Kohlhaas M et al. (2017) Refraktive Chirurgie mit dem Excimerlaser – Bewährt und sicher. Ophthalmologische Nachrichten 10.2017
- Kohnen T, Strenger A, Klaproth OK (2008) Basiswissen refraktive Chirurgie. Korrektur von Refraktionsfehlern mit modernen chirurgischen Verfahren. Dtsch Arztebl 2008; 105(9): 163-72. doi: 10.3238/arztebl.2008.0163
- Kommission Refraktive Chirurgie der DOG und des BVA (2016) Bewertung und Qualitätssicherung refraktiv-chirurgischer Eingriffe durch die DOG und den BVA – KRC-Empfehlungen. Berufsverband der Augenärzte Deutschlands (BVA), Düsseldorf