The cornea is the window at the front of the eye. In the normal eye the cornea is clear. Light is able to enter the eye through the clear cornea, pass through the clear lens to focus on the retina at the back of the eye. When the cornea is deformed or damaged from injury or disease light cannot pass freely to the retina. The picture that the retina passes to the brain is not clear and sight is reduced.
Corneal Graft = Keratoplasty
The chief function of the cornea is to help focus and transmit light. When this is interfered with by either irregularity, scarring or waterlogging and cannot be helped any more by any other treatment (either eye drops, drugs, spectacles or contact lenses) a corneal graft may be performed to:
- Improve your sight
- Alleviate your pain
- Repair a perforation (if your cornea has ruptured)
In a corneal graft operation part of your cornea is removed and replaced with a similar piece of cornea from a donor eye.
- Penetrating keratoplasty: the full thickness of the cornea is replaced
- Deep lamellar keratoplasty: the anterior/front 90% is replaced
- DSEK endothelial keratoplasty: the posterior/back endothelial layer is replaced, with the rest of the cornea untouched
Many people donate parts of their body, including their corneas in order to help others after their death. The individual, or family, consent to the use of the eyes for medical purposes after their death e.g. by carrying a donor card. The donor cornea is taken from an eye which has been removed from a person who has died.
It is usually necessary to wait for some time until a cornea in the correct condition is available. This may mean waiting for someone to die for “material” to become available.
Corneas are not taken from donors known to have infectious conditions. All donors are screened for carriers of AIDS or Hepatitis viruses before their corneas are used. The cornea is treated with antibiotic solution before being used for your operation. Unfortunately, not all conditions can be detected, and it is not possible to guarantee that the donor cornea is free from infection. The risk of CJD (brain disease) from corneal grafting is unknown. I use donor corneas from the United Kingdom Transplant Centre in Bristol, which has rigorous procedures to ensure the best quality and safest corneal tissue.
Serious complications may occur following graft surgery (see Risks). Keratoplasty is a major eye operation and like all operations may be accompanied by complications including haemorrhage (bleeding in the eye) and damage to other parts of the eye. The period after the operation can be complicated by infection, rejection, glaucoma, cataract and retinal detachment, as well as other, less common complications.
The post-operative care of a corneal graft is critical to achieving the desired outcome of a clear graft with good vision. Therefore, it is essential that you keep your follow-up appointments, and seek prompt medical help should sudden or severe symptoms occur.
Eye drops are very important after the operation in preventing infection, inflammation and other complications. I may ask you to put in eye drops for 12 months or more after the operation.
Donor corneal grafts may be rejected by your body if your body recognises the foreign tissue and your immune system then tries to damage it. This is not an “all or nothing” condition, and provided it is diagnosed early enough it can usually be successfully treated. Please seek prompt medical advice if you experience one or more of the following:
- Decrease in sight
- Redness of the eye
Rejection can occur at ANY time after a corneal graft, even years later after your discharge from Outpatients. Rejections occur more often in the first year after the operation following a change of treatment, after removal of stitches, as a result of eye infection or injury.
Failure to obtain the correct treatment early can result in permanent loss of sight and the need for a repeat operation which carries a higher risk of failure than the first.
What are the chances of my graft being successful?
The success rate is good (e.g. ~90% of corneas grafted for keratoconus still clear 5 years after surgery) but it varies depending on the reason why you need a corneal graft and your general health.