Cornea

Definition:

The cornea is the eye's window to the world. As the arched anterior part of the eye, it is crystal-clear and moistened by lachrymal fluid.

Indications for a cornea transplant:

Pathologic clouding of the cornea due to congenital developmental disorders of the eye, scarring due to injuries, infections or ulceration. Hereditary ailments or metabolic disorders can also cause clouding of the cornea.

Frequency and demand:

Cornea transplants are the most common transplant surgery. About 500 transplants are performed every year in Switzerland and the worldwide count is estimated at over 100,000.

Since it is not possible to use all donated corneas for transplants, the demand for corneas is actually significantly greater than the number of transplants. The actual condition of a cornea is what determines whether it is suitable for transplanting, and particularly the cell density on its rear side.

Transplanting corneas:

A cornea transplant involves removing the damaged cornea and replacing it with another human cornea. The transplanted cornea is either stitched in with fine needles or it can also be glued into place. Each transplant requires intensive post-operative treatment along with regular checkups. Although there are cases where a cornea is rejected, cornea transplants do have an outstanding prognosis: Rejections are very rare (even though they can occur as a function of the underlying ailment).

The visual acuity that can be achieved post-transplant depends on the healing process, the quality of the transplanted cornea and the condition of the retina, the optic nerve and the lens. Once the stitches are removed, glasses or contact lenses can be prescribed as required.

Heart valves

Definition:

There are three possible transplant types when heart valves are involved. We basically distinguish between mechanical (artificial) and biological valves. Biological valves are broken down further into two categories: Xenograft (from cows, pigs or horses) and homograft (from humans).

The following text applies to homograft transplants. As a general rule, hearts from deceased organ donors or from living donors who are receiving a heart transplant are considered for heart valve donations if the donor is less than 65 years old.

Indications for a heart valve transplant:

Since the valve is removed along with the adjacent vessel section, homograft transplants are useful primarily for reconstructing complex congenital heart defects or in case of heart valve infections.

Frequency and demand:

Currently, about 75 homograft transplants are performed annually in Switzerland. Switzerland does not have a tissue bank for heart valves, and as a result the necessary transplants are imported from other countries. In 2007, only about one fifth of the needed heart valves from donors in Switzerland were exported to other countries for preparation.

Bone

Definition:

Bone transplants are based on material from deceased donors (shinbone, femur, vertebral body or iliac crest) or from a living donor: Femoral heads of patients receiving an artificial hip joint are used as the starting material. Bone tissue can be transferred from one's own body. Bone replacement material can also be used as a substitute.

Indications for transplantation of bone or cartilage:

If there is insufficient bone matter in a certain area, it can become necessary to perform a bone transplant. A bone transplant is generally performed in cases where there is excessive loss of (intact) bone matter. For example, this can happen in case of a severe injury (broken bone), a bone infection, pseudarthrosis (improper healing of a broken bone), tumour surgery or when exchanging an artificial joint. Bone transplants are also used in the field of dentistry to remedy major problems such as occur with cysts, tumours and fractures and also as a basis for subsequent implants.

Broken bones generally result from some physical injury involving an accident, sports or a fall. Broken bones can also occur with less severe provocation in case of exposure to continuous stress (fatigue fracture, stress fracture). Osteoporosis and other ailments where there is a loss of bone matter can also cause broken bones.

Frequency in Switzerland:

In Switzerland, between 400 and 500 bone transplants are performed annually.

Blood vessels

Definition:

In the area of blood vessels, one must distinguish between arteries and veins. Arteries carry oxygenated blood from the heart to the organs and body tissue. Veins carry deoxygenated blood back to the heart.

Indications for transplantation of blood vessels:

Blood vessel transplants are used in case of vascular obliterations, severe blockages or thromboses. Such transplants are commonly performed in the thorax region (aorta) as a lifesaving operation, and also in the legs, the abdomen and the neck and head regions.

Amnion

Definition:

Amnion forms part of the membrane which surrounds a foetus in the womb.

Indications for transplantation of amnion:

For treatment of surface wounds to the conjunctiva and/or cornea.

Donating amnion:

Amnion generally comes from living donors (mothers) who consent to donate during childbirth.

Transplanting amnion:

Amnion transplants represent a transitional therapy. After a few weeks, it disintegrates and the body's own cells regenerate the treated area. Amnion is used primarily to cover wounds so that lesions to the conjunctiva and/or cornea can heal underneath it.

Skin

Definition:

As the body's outer layer, the skin's main function is to protect the body against infection, desiccation, radiation and cold temperatures.

Indications for transplantation of skin:

In cases where skin cannot regenerate itself or a wound cannot be closed with a suture, a skin transplant can be indicated. This happens most commonly in case of large-scale, third-degree burns, chronic ulceration or following certain types of surgery.

Transplanting skin:

Since skin transplants are rejected by the body without special medicinal treatment, they are used primarily as a temporary cover for large wounds.