The Cornea-the transparent front window of the eye-is one of the body's most sensitive tissues, constantly cleansed of dirt and debris by blinking and tears. If the outer most layers of corneal cells are damaged, it soon regenerates. But some eye insults-injuries, infections, chemical burns-cause permanent damage. Light is prevented from reaching the retina and vision is impeded.

Corneal replacement is the oldest of the transplants, pioneered in Europe in 1905 and first introduced into the UK in the 1930's. The operation is Britain's commonest and most successful transplant procedure: fewer than 1 in 5 grafts go wrong.

Corneal patients may be offered full thickness grafting (penetrating keratoplasty) or, less commonly, a newer technique in which only a partial thickness of the cornea is replaced. Full thickness grafting is carried out under a general anaesthetic and takes about an hour. The patient's own corneal button is removed and a disc cut from the donor cornea is stitched in its place. Some patients see the next day; other may have to wait for a while for the operated eye to reach its optimal effect.

This is an operation which does not rely solely on multi organ donors; graft material can come from any source, including donors dying at home, so long as removal is carried out within 24 hours of death. For varying temperature in India it is being collected within 6 hours. Also, cornea donors can be of any age. Donated corneas can be kept for up to 30 days.