Corneal transplant Health Dictionary

Also known as keratoplasty. If the cornea (see EYE) becomes damaged or diseased and vision is impaired, it can be removed and replaced by a corneal graft. The graft is taken from the cornea of a human donor. Some of the indications for corneal grafting include keratoconus (conicalshaped cornea), corneal dystrophies, severe corneal scarring following HERPES SIMPLEX, and alkali burns or other injury. Because the graft is a foreign protein, there is a danger that the recipient’s immune system may set up a reaction causing rejection of the graft. Rejection results in OEDEMA of the graft with subsequent poor vision. Once a corneal graft has been taken from a donor, it should be used as quickly as possible. Corneas can be stored for days in tissue-culture medium at low temperature. A small number of grafts are autografts in which a patient’s cornea is repositioned.

The Department of Health has drawn up a list of suitable eye-banks to which people can apply to bequeath their eyes, and an o?cial form is now available for the bequest of eyes. (See also DONORS; TRANSPLANTATION.)... corneal graft

The procedure by which malignant or defective bone marrow in a patient is replaced with normal bone marrow. Sometimes the patient’s own marrow is used (when the disease is in remission); after storage using tissue-freezing technique (cryopreservation) it is reinfused into the patient once the diseased marrow has been treated (autologous transplant). More commonly, a transplant uses marrow from a donor whose tissue has been matched for compatibility. The recipient’s marrow is destroyed with CYTOTOXIC drugs before transfusion. The recipient is initially nursed in an isolated environment to reduce the risk of infection.

Disorders that can be helped or even cured include certain types of LEUKAEMIA and many inherited disorders of the immune system (see IMMUNITY).... bone marrow transplant

A procedure in which cells – for example, from the pancreas – are taken from an aborted FETUS and then transplanted into the malfunctioning organ (pancreas) of an individual with a disorder of that organ (in this case, diabetes). The cells from the fetus are intended to take over the function of the host’s diseased or damaged cells. Fetal brain cells have also been transplanted into brains of people suffering from PARKINSONISM. These treatments are at an experimental stage.... fetal transplant

See: EYES, INFECTION. ... corneal ulcer

Transplantation of tissues or organs of the body are de?ned as an allotransplant, if from another person; an autotransplant, if from the patient him or herself – for example, a skin graft (see GRAFT; SKIN-GRAFTING); and a xenotransplant, if from an animal.

The pioneering success was achieved with transplantation of the kidney in the 1970s; this has been most successful when the transplanted kidney has come from an identical twin. Less successful have been live transplants from other blood relatives, while least successful have been transplants from other live donors and cadaver donors. The results, however, are steadily improving. Thus the one-year functional survival of kidneys transplanted from unrelated dead donors has risen from around 50 per cent to over 80 per cent, and survival rates of 80 per cent after three years are not uncommon. For a well-matched transplant from a live related donor, the survival rate after ?ve years is around 90 per cent. And, of course, if a transplanted kidney fails to function, the patient can always be switched on to some form of DIALYSIS. In the United Kingdom the supply of cadaveric (dead) kidneys for transplantation is only about half that necessary to meet the demand.

Other organs that have been transplanted with increasing success are the heart, the lungs, the liver, bone marrow, and the cornea of the eye. Heart, lung, liver and pancreas transplantations are now carried out in specialist centres. It is estimated that in the United Kingdom, approximately 200 patients a year between the ages of 15 and 55 would bene?t from a liver transplant if an adequate number of donors were available. More than 100 liver transplants are carried out annually in the United Kingdom and one-year-survival rates of up to 80 per cent have been achieved.

The major outstanding problem is how to prevent the recipient’s body from rejecting and destroying the transplanted organ. Such rejection is part of the normal protective mechanism of the body (see IMMUNITY). Good progress has been made in techniques of tissue-typing and immunosuppression to overcome the problem. Drugs are now available that can suppress the immune reactions of the recipient, which are responsible for the rejection of the transplanted organ. Notable among these are CICLOSPORIN A, which revolutionised the success rate, and TACROLIMUS, a macrolide immunosuppressant.

Another promising development is antilymphocytic serum (ALS), which reduces the activity of the lymphocytes (see LYMPHOCYTE) cells which play an important part in maintaining the integrity of the body against foreign bodies.

Donor cards are now available in all general practitioners’ surgeries and pharmacies but, of the millions of cards distributed since 1972, too few have been used. The reasons are complex but include the reluctance of the public and doctors to consider organ donation; poor organisation for recovery of donor kidneys; and worries about the diagnosis of death. A code of practice for procedures relating to the removal of organs for transplantation was produced in 1978, and this code has been revised in the light of further views expressed by the Conference of Medical Royal Colleges and Faculties of the United Kingdom on the Diagnosis of Brain Death. Under the Human Tissue Act 1961, only the person lawfully in possession of the body or his or her designate can authorise the removal of organs from a body. This authorisation may be given orally.

Patients who may become suitable donors after death are those who have suffered severe and irreversible brain damage – since such patients will be dependent upon arti?cial ventilation. Patients with malignant disease or systemic infection, and patients with renal disease, including chronic hypertension, are unsuitable.

If a patient carries a signed donor card or has otherwise recorded his or her wishes, there is no legal requirement to establish lack of objection on the part of relatives – although it is good practice to take account of the views of close relatives. If a relative objects, despite the known request by the patient, sta? will need to judge, according to the circumstances of the case, whether it is wise to proceed with organ removal. If a patient who has died is not known to have requested that his or her organs be removed for transplantation after death, the designated person may only authorise the removal if, having made such reasonable enquiry as may be practical, he or she has no reason to believe (a) that the deceased had expressed an objection to his or her body being so dealt with after death, or (b) that the surviving spouse or any surviving relative of the deceased objects to the body being so dealt with. Sta? will need to decide who is best quali?ed to approach the relatives. This should be someone with appropriate experience who is aware how much the relative already knows about the patient’s condition. Relatives should not normally be approached before death has occurred, but sometimes a relative approaches the hospital sta? and suggests some time in advance that the patient’s organs might be used for transplantation after death. The sta? of hospitals and organ exchange organisations must respect the wishes of the donor, the recipient and their families with respect to anonymity.

Relatives who enquire should be told that some post-mortem treatment of the donor’s body will be necessary if the organs are to be removed in good condition. It is ethical (see ETHICS) to maintain arti?cial ventilation and heartbeat until removal of organs has been completed. This is essential in the case of heart and liver transplants, and many doctors think it is desirable when removing kidneys. O?cial criteria have been issued in Britain to recognise when BRAIN-STEM DEATH has occurred. This is an important protection for patients and relatives when someone with a terminal condition

– usually as a result of an accident – is considered as a possible organ donor.... transplantation

The insertion of a piece of bone from another site or from another person to ?ll a defect, provide supporting tissue, or encourage the growth of new bone.... bone transplant

Instinctive closing of the eyelids when the surface of the cornea (see EYE) is lightly touched with a ?ne hair.... corneal reflex

An operation in which a patient’s diseased lungs and heart are removed and replaced with donor organs from someone who has been certi?ed as ‘brain dead’ (see BRAIN-STEM DEATH). As well as the technical diffculties of such an operation, rejection by the recipient’s tissues of donated heart and lungs has proved hard to overcome. Since the early 1990s, however, immunosuppressant drug therapy (see CICLOSPORIN; TRANSPLANTATION) has facilitated the regular use of this type of surgery. Even so, patients receiving transplanted hearts and lungs face substantial risks such as lung infection and airway obstruction as well as the long-term problems of transplant rejection.... heart-lung transplant

UK legislation that lays down the framework and rules governing organ transplantation. The UK Transplant Support Service Authority (UKTSSA), a special health authority set up in 1991, is responsible for administering the NHS Organ Donor Registry and the Act (see APPENDIX 7: STATUTORY ORGANISATIONS).... human organs transplants act

See TRANSPLANTATION.... organ transplantation

These have almost completely replaced BONE MARROW TRANSPLANT, used to treat malignancies such as LEUKAEMIA and LYMPHOMA for the past 20 years. The high doses of CHEMOTHERAPY or RADIOTHERAPY used to treat these diseases destroy the bone marrow which contains stem cells from which all the blood cells derive. In 1989 stem cells were found in the blood during recovery from chemotherapy. By giving growth factors (cytokines), the number of stem cells in the blood increased for about three to four days. In a peripheral-blood stem-cell transplant, these cells can be separated from the peripheral blood, without a general anaesthetic. The cells taken by either method are then frozen and returned intravenously after the chemotherapy or radiotherapy is completed. Once transplanted, the stem cells usually take less than three weeks to repopulate the blood, compared to a month or more for a bone marrow transplant. This means that there is less risk of infection or bleeding during the recovery from the transplant. The whole procedure has a mortality risk of less than 5 per cent – half the risk of a bone marrow transplant.... peripheral-blood stem-cell transplants

Before the advent of small-bowel transplants, long-term intravenous feeding (total parenteral nutrition or TPN) was the last option for patients with chronic intestinal failure. Most recipients are children, and small-bowel transplantation is currently reserved for patients unable to continue on long-term parenteral nutrition. The main constraints to small-bowel transplantation are the intensity of rejection (necessitating high levels of immunosuppression), and the lack of donors who are the same size as the recipient (a particular problem for children).... small-bowel transplantantion

In the UK, this NHS authority (UKTSSA) provides a 24-hour service for matching, allocating and distributing organs. It is also responsible for keeping the records of all patients awaiting transplants. Established in 1991, the authority allocates donor organs without favour, following protocols set by advisory groups. It also administers the Human Organ Transplant Act on behalf of the Department of Health. (See TRANSPLANTATION.)... transplant support services authority

A scratch or defect in the epithelium (outer layer) of the cornea caused by a small, sharp particle in the eye (see eye, foreign body in) or by an injury. Corneal abrasions usually heal quickly but may cause severe pain and photophobia. Treatment includes covering the eye with a patch, analgesic drugs to relieve pain, and, if the eye muscles go into spasm, eyedrops containing cycloplegic drugs (which paralyse the ciliary muscle, preventing accommodation). Antibiotic eyedrops are usually

given to prevent bacterial infection, which can lead to a corneal ulcer.... corneal abrasion

Another term for kidney transplant.... renal transplant

a white or greyish line in the periphery of the cornea, concentric with but separated from the edge by a clear zone. It begins above and below but may become a continuous ring. It consists of an infiltration of fatty material and is common in the elderly (arcus senilis). When it occurs in younger people (arcus juvenilis) it may indicate *hyperlipidaemia. It does not affect vision.... corneal arcus

A cosmetic operation in which hairy sections of scalp are removed and transplanted to hairless areas to treat alopecia (baldness). There are several different techniques.

In strip grafting, a strip of skin and hair is taken from a donor site, usually at the back of the scalp or behind the ears. The removed hairs and their follicles are then inserted into numerous incisions made in a bald area, known as the recipient site. The procedure usually takes 60–90 minutes. The patient is given a mild sedative and anaesthetic on the donor and recipient sites. The donor site heals in about 5 days. Transplanted hairs fall out shortly afterwards, but new hairs grow from the follicles 3 weeks to 3 months later.

Other transplant techniques include punch grafting, in which a punch is used to remove small areas of bald scalp, which are replaced with areas of hairy scalp; flap grafting, in which flaps of hairy skin are lifted, rotated, and stitched to replace bald areas; and male pattern baldness reduction, which involves cutting out areas of bald skin and stretching surrounding areas of hair-bearing scalp to replace them.... hair transplant

Replacement of a patient’s damaged or diseased heart with a healthy heart taken from a donor at the time of death. Typically, transplant patients have advanced coronary artery disease or cardiomyopathy. During the operation, the function of the heart is taken over by a heart–lung machine.

Most of the diseased heart is removed, but the back walls of the atria (upper chambers) are left in place.

The ventricles (upper chambers) are then attached to the remaining areas of the recipient’s heart.

Once the immediate post-operative period is over, the outlook is good.

Patients face the long-term problems associated with other forms of transplant surgery.

(See also heart–lung transplant.)... heart transplant

Replacement of a diseased liver with a healthy liver removed from a donor. Liver transplants are most successful in the treatment of advanced liver cirrhosis in people with chronic active hepatitis or primary biliary cirrhosis. People who have primary liver cancer are rarely considered for transplantation because there is a high risk that the tumour will recur.During this procedure, the liver, gallbladder, and portions of the connected blood and bile vessels are removed.

The donor organs and vessels are connected to the recipient’s vessels.

After the transplant, the recipient is monitored in an intensive care unit for a few days and remains in hospital for up to 4 weeks.... liver transplant

Replacement of a diseased organ or tissue with a healthy, living substitute. The organ is usually taken from a person who has just died. Some kidneys are transplanted from a patient’s living relatives (see organ donation). The results of surgery have also been improved by testing for histocompatibility antigens and tissue-typing.

Rejection is a major problem. However, a combination of a corticosteroid drug and ciclosporin are given in order to suppress this response.

Every patient who undergoes an organ transplant operation must take immunosuppressant drugs indefinitely. (See also heart transplant; heart–lung transplant; liver transplant; kidney transplant.)... transplant surgery

reflex blinking of both eyes normally elicited by lightly touching the cornea of one eye. This reflex is lost in deep coma, during general anaesthesia, and in death; it is therefore one of the tests used to confirm brainstem death.... corneal reflex

a ring designed to be inserted into the peripheral tissue of the cornea in order to alter the curvature of the corneal surface. It is undergoing trials to assess its ability to correct errors of refraction. In myopia (short-sightedness), for example, the ring would be required to stretch the corneal tissue peripherally and thus flatten the central corneal curvature in order to correct the myopia.... corneal ring

(videokeratography) an imaging technique used to study the shape and refractive power of the cornea in detail. An image projected onto the cornea is analysed by a computer to produce a representation of the shape and refractive power of the corneal surface. Corneal topography has an important role in the management of corneal disease and refractive surgery.... corneal topography

see orthotopic transplantation.... heterotopic transplantation

a new technique still under evaluation for curing type 1 *diabetes mellitus, which involves the injection of donated cells from the pancreatic *islets of Langerhans into the liver, where it is hoped they will seed and survive. The transplanted cells then take over insulin production from the recipient’s diseased pancreas.... islet cell transplantation

(NHSBT) a *special health authority established in 2005 to provide a safe and reliable supply of blood, organs, stem cell services, and diagnostics to hospitals. NHSBT also provides specialist therapeutic apheresis services, which remove or replace a single component of blood (e.g. malignant white cells or low-density lipoprotein), at six sites in England.

NHS Blood and Transplant website... nhs blood and transplant

transplantation of a donor organ or tissue (usually the liver) into a recipient at the site where the recipient’s organ has been removed. In contrast, heterotopic transplantation involves the preservation of the recipient’s organ in its natural site and the addition of the donor organ at another site.... orthotopic transplantation

see transplantation.... renal transplantation