What is keratoplasty?Keratoplasty is an operation on the cornea of the eye. Thereby a cornea transplantation takes place.
Keratoplasty is one of the eye surgeries. In this case, tissue of the cornea (cornea), which is diseased, replaced by donor material, which is a cornea transplantation. In addition, as part of a keratoplasty, a physical action on the tissue of the cornea can be made to change the corneal power. In this way, defective eyesight can be treated.
For a cornea transplant, a suitable donor material is needed by a human. The corneas, which are used for transplantation, are taken from deceased persons. They have already approved the removal during their lifetime. The administration of the donor corneas takes place through a special cornea bank. To ensure the integrity of the corneas, their storage takes place in nutrient fluid. Also important is a good compatibility of the organ to counteract rejection reactions. The cornea of the eye is its anterior outer shell. It is transparent and smooth.
Due to its curvature, it reaches a certain refractive power. Together with the eye lens, the cornea focuses the incoming rays of light, forming a sharp image on the retina of the eye.
Function, effect & goals
In keratoplasty, it is important to distinguish between three different types. These include thermokeratoplasty, perforating keratoplasty and lamellar keratoplasty. In the context of thermokeratoplasty, the curvature of the cornea is influenced by the local action of heat. This procedure counts for refractive surgery and does not require cornea donor tissue.
The situation is different with perforating keratoplasty. In this method, all layers of the damaged cornea are removed as part of the intervention by trepanation. The surgeon then inserts the donor's corneal discs. Lamellar keratoplasty is when the grafting of individual layers is isolated. In this case, for example, a corneal disc can be sewn onto the cornea, which can be compared with a contact lens.
Keratoplasty is intended to enable the patient to achieve optimal vision without visual aids. Not infrequently, however, may remain as a result of surgery, an irregular astigmatism, the compensation takes place by a dimensionally stable contact lens. There are several indications that cause severe damage to the cornea, requiring keratoplasty. These may be severe bacterial inflammation of the cornea, mechanical injury resulting in corneal puncture, burns, burns, or corneal ulcers.
In some cases hereditary diseases or severe inflammations such as fox endothelial dystrophy or keratoconus, in which the cornea bulges like a cone, lead to corneal damage. Other indications include severe corneal opacities and corneal scar, which severely affects eyesight. Depending on the extent either a lamellar or a perforating keratoplasty takes place. For a corneal transplant to be performed, the patient must meet certain requirements. So he should be able to close his eyelids completely, have a normal intraocular pressure and have a sufficient tear film.
Before a perforating keratoplasty, the patient usually receives a general anesthetic. Likewise, a local anesthesia is possible. First step of the procedure is the cutting out of the damaged cornea in a special size. The surgeon cuts the donor's cornea so that it can be planted exactly in the resulting gap. The recommended diameter is between 6.5 and 8.5 millimeters. After insertion of the corneal disks, their fixation takes place with a fine suture.
As part of a lamellar keratoplasty, the surgeon only removes the front part of the cornea and replaces it. By contrast, the inner layers of fabric remain in place. However, lamellar keratoplasty is rarely used, as it is considered more difficult than penetrating keratoplasty, which involves complete replacement of the cornea.
Risks, side effects & dangers
Performing a keratoplasty is not free of risks. Thus, there is a risk that various eye parts or adjacent body structures are affected by the procedure.
Rarely, it comes to bleeding, but can never be completely ruled out. Likewise, infections can occur. Furthermore, it is possible that a loosening of the threads of the corneal suture occurs. If there is no tight closure of the cornea, the laying of additional threads is usually necessary.
Further conceivable complications after keratoplasty are disorders of the healing process of the cornea as well as the occurrence of corneal opacities or scars. In extreme cases, the sight of the eye deteriorates significantly. Even blindness and the loss of the eye are in the realm of possibility. However, these serious complications are extremely rare.
In addition, since perforating keratoplasty is a transplant, there is a risk of rejection of the tissue that has been newly implanted. However, the risk is lower in the case of corneal transplantation, since there is no blood flow to the corneas. However, after chemical burns or inflammation, blood vessels can form on the recipient cornea, increasing the risk of rejection.
So that it does not even come to a rejection reaction, the patient receives immunosuppressants in the form of eye drops. These have the property to suppress the body's defense reactions, counteract infections and inhibit inflammation. In addition, the ophthalmologist must conduct regular check-ups. After a period of one year, the ophthalmologist gently pulls the threads on the cornea, giving the patient local anesthesia.