Corneal Transplant

Corneal Transplant and Eye-banking

The cornea is a delicate transparent watch-glass-like tissue-about 11-12 mm in diameter and about 1mm in thickness-that covers the black window of the eye. It is aptly called the human window to the world. It is a component of the eyeball and is vital for sight. It receives parallel rays of light from external objects and transmits them onto the lens and the retina, and finally to the brain to be realized in the form of visible objects.

It being exposed to the external atmosphere, the cornea is vulnerable to the kind of external injuries and infections from viruses, bacteria and fungi. It is also very susceptible to gross malnutrition, prolonged heat exposure and diseases of the other components of the eyeball. The end result of all these maladies, if not treated properly, is a residual opaque scar. Once the opacity is deep set it cannot be removed by any medicine whatsoever.

The first operation of corneal transplant became a recognized surgical procedure in the days of Markus and Von Hipper in the year 1841. A corneal graft simply consists of removing this white opacity from the cornea of the patient and replacing it with an identical size tissue of clear, fresh and healthy cornea, obtained from human cadaver (dead body) within three or four hours of death. We remove the cornea only from the whole eye and transplant it. The surgeon only transplants or changes the cornea and not the whole eyeball. The erroneous notion that the whole eyeball can be transplanted still exists and people sometimes travel long distances to ask if the whole eyeball can be replaced, which something is that cannot be done.

The cornea of a dead body is living if it is removed within three to four hours of death. The life-giving nutrition of the cornea does not come from blood but from the aqueous fluids within the eyeball. When death comes to the human body, the cornea continues to get supply of nutrition from the eyeball and thus remains transparent and viable in a transplant operation. The rejection of corneal tissue by tissue immunization is not as violent as that of the heart and kidney because of the simple fact that, unlike the heart and kidney, the corneal tissue has no blood circulation. The antigen antibody reaction is minimal if the donor tissue is fresh or is maintained fresh and is sutured to the recipient with precision and minimal tissue trauma by an operating microscope and microscopic instruments.

It is very important to carry out a complete systematic examination of the patient to exclude the following diseases before a corneal transplant operation:

1. diabetes;
2. blood pressure;
3. severe cough and cold; and
4. Systematic infections of ENT, dental, urine-genital and chest.

A complete examination of the recipient’s eye and treatment ‘of any complications if seen must also be carried out before surgery.

A successful corneal graft will depend upon the following major factors.

1. A successful take of the graft.
2. A successful restoration of sight.
3. An absence of graft rejection or reaction episode either short or delayed.

A successful ‘take’ of the graft depends on the following:

1. Freshness of donor eyeball-the eyeball should be as fresh from the dead body as it can be or should be maintained fresh in a culture medium by an eye bank.
2. The surgical technique used must be precise and with minimal tissue trauma. It should be performed under a microscope with microsurgical instruments and full asepsis.
3. The trephines and sutures used must be precise. The sutures are microscopic and extremely thin (thinner than human hair).

A successful restoration of sight depends on:

1. Successful ‘take’ of the graft.
2. The state of health of other components of the eyeball. If they- are not healthy the sight restoration may not be complete even when the graft is clear and successful.

The patient stays in the hospital for four to seven days. Once the graft stays clear and bright for three to six months, it stays clear if tissue rejection does not take place. Post-operative follow-up is vital to eliminate recurrence of pacification.

The sight restoration may not be complete in lazy eyes. An absence of tissue-immune reaction or ‘rejection phenomenon’ will keep the graft clear and successful. But the course of Nature takes it beyond the reach of the surgeons and the patient. Immune reaction can affect a cornea-as early or as late as three to five years after surgery.

Some eyes are lazy and amblyopic due to a suppression of visual stimulus to the brain. This can happen in corneas that are opaque since childhood.

The average success rate figure of an ideal corneal graft is 60. Per cent.

Role of an Eye Bank in Corneal Surgery

An eye bank isa laboratory where donated eyeballs are received stored and transported under strict aseptic care till they are required by the ophthalmic surgeon for corneal transplant. The eyeball is stored in specific chemicals and under controlled refrigeration with all aseptic precautions.

An eye bank is also an institution which propagates the donation of eyes from the members of public at large. The help of social workers, local press, films and TV is a ‘must’ for wide publicity essential to the running of an eye bank. The team of eye bank officers, social workers, technicians and corneal eye surgeons works in close cooperation for creating awareness and motivating eye donations from members of the public at large. It also conducts a chain reaction beginning with eye donation to its final utilization by the corneal surgeons for successful graft on a carnally blind person and restoring his /her sight.

The eye bank also undertakes research of corneal issue problems and prevention of blindness. The purpose of an eye bank is not completely served unless it has a fully equipped pathological laboratory.

Procedure of Donating Eyes to an Eye Bank

There are two categories for donation. Each category is required to fill up a printed form from the eye bank.

1. Donation by the living being (will of donation). A living person who wants to donate his eyes after his death is required to fill forms and send them to the bank. This is like making a will. After the death of such a person is announced, the relation or next of kin informs the eye bank to fulfill the donor’s wish.
2. Donation after death by the consent of next of kin.

The donations can also com from a relation or next of kin of a person soon after his/her death within two hours of death. The ideal age of the donor is between five to sixty years. It is always good to obtain fresh eyeballs of young donors within few hours of death. The relation or next-of-kin signs a form of consent from an eye bank and calls the eye bank for donation. On being called by relatives, a trained medical officer sets out to the location and removes the eyeballs under strict asepsis and brings them to the eye bank for storage. Controlled refrigeration and sophisticated chemicals and antibiotics are -essential at every step. The fresh eyeballs can be used by the surgeon for the corneal transplant within 24 hours. If required to be used after a longer period, Le. Four to six days, the cornea is preserved in a culture medium of special biochemical nature. The culture media available are M.K. Media, Dexol, etc.  

Difficulties Faced by Surgeons

The difficulties faced by surgeons of cornea when asking for eye donations are the following:

1. Lack of public awareness and education to volunteer to donate eyes.
2. Traumatic and emotionally charged atmosphere when the next of kin of dead is asked to sign the form for eye donation. He or she may refuse to do so at the tragic moment.
3. Religious belief that the body must be buried or burnt without being mutilated.
4. Legislation in India is not yet favorable for removing eyeballs from a dead body without the written consent of the next of kin/ relation. The dead body belongs to the relations or next of kin, not to the federal state. Eyeballs cannot be taken even from bodies for post-mortem and from victims of road accidents without the consent of a coroner and a relative respectively.

The cornea from the eyeball is removed within two three hours of death if the relations do not object. The doctors can take the cornea from the dead body without disturbing the rest of the eyeball.