If the eye cannot image an object sharply on the retina under standard conditions, there is a refractive error. The ophthalmologist then speaks of ametropia.
If the reason is that the eyeball is too short or too long, this is called axial ametropia.
In the case of myopia (short-sightedness) , the eyeball is too long in relation to the refractive power. In hypermetropia (farsightedness), it is too short.
If the light refracts too strongly or too weakly at the lens or the cornea, doctors call this refractive ametropia.
If the cornea is not spherically curved as normal, the cornea is curved.
A cataract is a clouding of the lens.
Experts in refractive surgery treat the following visual defects and eye diseases, among others :
Refractive surgery includes eye procedures that change the overall refractive power of the eye @ Koldo_Studio /AdobeStock
Every ophthalmologic examination includes asking the patientabout any complaints or eye diseases that run in the family. Doctors check visual acuity using eye charts.
The doctor can use refractometry and skiascopy to objectively determine refraction.
The principle of refractometry is based on the observation of an image projected onto the retina. Doctors determine the additional refractive power required to obtain a sharp image on the retina.
With skiascopy, doctors can identify the type of defective vision by observing light reflexes on the retina.
During a subjective refraction test, the doctor asks which lens gives a better visual impression.
The surgical correction procedures belong 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.
Corneal refractive surgery procedures:
In photorefractive keratectomy (PRK), doctors ablate the cornea with an excimer laser as follows:
- layer-by-layer ablation
- ablation at the edge only or
- oval ablation
Layered ablation and peripheral ablation are used to correct myopia.
Oval ablation is suitable for correcting astigmatism.
LASEK (laser subepithelial keratomileusis) and the Epi-LASEK procedure also treat the surface of the cornea with the excimer laser. In this way, defective vision can also be corrected.
In LASIK (laser in situ keratomileusis), doctors first cut off part of the cornea and fold it over. They then use a laser to abrade the inside of the cornea. They then fold back the folded cornea.
Modern forms of LASIK are:
Before the laser removes the tissue in the cornea, the doctor makes an incision to open a thin flap in the cornea @ RFBSIP /AdobeStock
Refractive lenticule extraction (RELEX) processes the cornea using only a femtosecond laser (hence FLEX or femtosecond laser lenticule extraction).
SMILE is a special method.
Other procedures are:
- Astigmatic keratotomy and
- Limbal relaxing incisions (LRI)
The implantation of ring segments in the outer cornea (intracorneal ring segments) and corneal cross-linking.
Refractive lens surgery procedures:
When implanting phakic (additional) intraocular lenses (phakic IOL, PIOL), doctors supplement the natural lens with an artificial lens.
In refractive lens exchange (RLA), doctors replace the natural lens of the eye with an artificial lens.
Experts in refractive surgery are specialists in ophthalmology who have particular experience in the field of eye surgery.
Thanks to their specialist training and professional activity, they are able to recognize refractive errors and treat them using current and new procedures.
In addition, these ophthalmic surgeons also have special surgical skills in refractive surgery procedures.