Corneal Transplant

(Penetrating Keratoplasty)

Advice for patients

What is a corneal transplant?

A corneal transplant, sometimes called a corneal graft or keratoplasty, involves replacing the central portion of patients cornea with a normal cornea removed from a recently deceased donor. Using microsurgical techniques, the diseased central cornea is removed and the donor cornea is stitched into the defect with very fine nylon thread (suture).

Why are corneal transplants needed?

The cornea is the clear “watch glass” in the front of the eye. It is the most important lens in the eye and is perfectly transparent and perfectly shaped to focus light on the retina at the back of the eye. If the cornea is an abnormal shape, as in the very common disorder called keratoconus, or if it is opaque because of scarring, vision is greatly reduced. Under these conditions, it is possible to replace the diseased cornea with normal transplanted cornea.

How successful is corneal transplantation?

Corneal transplantation is the most widely practised and most successful form of transplantation carried out by surgeons. Rejection of the graft, a common problem for kidney, heart, liver and bone marrow grafts, is much less of a problem for corneal grafts. 

Rejection is unusual after corneal transplantation because the cornea usually does not have blood vessels. Without blood vessels the body's immune system is less likely to recognise and reject the “foreign” graft. The cornea in patients with keratoconus does not usually have blood vessels.

In other situations, where the cornea is opaque and scarred as a result of injury or infection, there may be blood vessels which have grown into the cornea during healing. Corneal grafts in such cases are at risk of rejection but steps can be taken to reduce this risk.

What is a successful corneal graft?

Sustaining a clear graft is essential if good vision is to be achieved. Furthermore the shape of the grafted cornea must be very close to the shape of patients cornea, before the eye became diseased. Advances in microsurgery have ensured that this can sometimes be achieved. Small variations in the shape of the cornea can affect vision, but can be overcome by the use of spectacles or contact lenses after the operation.

In patients with keratoconus, virtually normal vision (better than 6/12 line on the reading chart) can be achieved 90% of the time. With other conditions, it is necessary to take into account many factors affecting the eye before predicting the visual outcome. It is important to note however, that the best vision after the operation might not be achieved for 18 months after surgery. 

What are the risks?

All operations have their risks and the surgical staff are obliged to tell you what they are - and to inform patients of the risks of not having surgery.

By any surgical standards, corneal transplantation is safe surgery. The most significant risks are those of haemorrhage, infection and retinal detachment. Although these complications occur rarely (about 3 times in 1000 operations) they have serious consequences and could make the vision worse after the operation than before.

Rejection of the graft can occur, especially in patients who have had injuries, or infections, or previous operations on the eye. The risk of rejection is to be assessed for each particular case. Should rejection occur, vision is usually poor and replacing the graft may need to be considered.

Astigmatism is very common after corneal transplantation, and only when severe does it threaten the visual outcome. Astigmatism occurs when the curvature of the grafted cornea is distorted. A minor degree is almost inevitable and can be overcome by the patient wearing spectacles or in some cases contact lenses. Occasionally, when astigmatism is more marked, a small corrective operation is required to correct the distorted corneal shape. 

Patients are advised to stop playing contact sports after corneal transplantation because the weakest part of the eye becomes the corneal graft scar. Consequently any minor trauma such as a poke in the eye can result in rupture of the weak scar and damage to the graft.

When can the operation be done?

The operation is usually done at a time convenient to the patient and surgeon. Few corneal grafts are urgent. Corneal transplantation is most commonly done as an elective procedure. This means that the operation is scheduled and the donor cornea is made available at a pre-arranged time. The Eye Bank of South Australia is within Flinders Medical Centre and is almost always able to supply a suitable eye for transplantation as arranged. Very occasionally, the operation may be delayed due to non-availability of a donor.

Only the healthiest corneas from donors are used for transplantation. Eye Banks throughout Australia operate under the strictest guidelines regulated by the TGA. This ensures that only the safest and best quality tissue is distributed to surgeons for transplantation. In spite of this, for reasons that are not entirely clear, a corneal graft may fail to function in less than one in 100 cases.

Anaesthesia

Corneal transplantation can be done under general or local anaesthesia. Not all patients need to be put to sleep for surgery (general anaesthetic). For the majority of patients a local anaesthetic is preferred. With a local anaesthetic, an anaesthetic solution is delivered by a blunt cannula around the eye to completely remove all movement and sensation. Whenever possible a local anaesthetic is preferable, however, young adults tend to be more apprehensive and are best done with a general anaesthetic, as are children.

Do I need to come into hospital?

No, surgery is usually done as a day procedure. In some cases the patient may be admitted overnight. All patients need to come back to see the surgeon on the day after surgery. 

Is the post-operative period painful?

Not usually. There is always some discomfort after any operation but after a corneal transplant the discomfort is minimal. Panadol is usually enough medication to relieve pain.

When are the stitches removed?

The stitches are removed sometime after 12 months. Occasionally, should they loosen prematurely, they may be removed ahead of time. Whatever the timing, the stitches are nearly always removed eventually.

Stich (suture) removal is done in the clinic at the slit-lamp. The graft has no sensation because the nerves take years to grow into the graft. With a few drops of local anaesthetic, the stitches can be painlessly removed in a few minutes. 

How often will I need to see the doctor after surgery?

Close follow-up by the surgeon and his or her staff is very important. It can mean the difference between finishing up with a good result or a bad result. Ensuring that the supervision is adequate after surgery is the responsibility of the patient and the surgeon. Usually, patients with corneal grafts need to be seen on the day after surgery, then after a week, and again 4 weeks after surgery. Depending on the patient’s job, 1 – 2 weeks off work is usually advisable. Later they need to be seen at 3 months, 9 months and 12 months after surgery. At the 12 month visit, the stitches are sometimes removed.

What medication will I need?

Following surgery patients are given two different eye drops. One drop is an antibiotic and needs to be used 4 times a day for the first 1 - 2 weeks after surgery. The second is an anti-inflammatory agent and needs to be used 4 times a day for the first 3 months after surgery. After 3 months the frequency can be reduced, but most patients will require one or two drops a day for at least a year.

Will I need spectacles?

Patients usually need to wear spectacles to gain the very best vision. A small proportion, about 10%, will not. Another small group, again about 10%, will need contact lenses for the very best vision. Whether a patient will need spectacles or contact lens is usually not decided until the stitches are removed, which is not usually for 12 months after surgery. In the meantime, spectacles may be prescribed to help in the short term.

Occasionally neither spectacles nor contact lenses will provide the level of vision required because there is excessive astigmatism. In these cases a relatively minor operation may need to be carried out to reduce astigmatism. This operation is usually referred to as "relaxing incisions" and can be carried out under local anaesthetic on a day case basis.

How long will I need to be followed up after surgery?

Forever. However, after 12 months you will probably only need to be seen once a year. It is important to remember that although you can expect to achieve good vision after surgery, your graft will remain vulnerable for many years.

Should your eye ever become red or inflamed, or should your vision suddenly be reduced, you must seek professional attention immediately. Inflammation of any cause can bring on rejection and graft failure. Early attention to the cause of rejection can prevent graft failure.

There is someone on duty at Flinders Medical Centre 24 hours a day, 7 days a week to attend to patients who have concerns about their grafts.

What is rejection?

Rejection is the term applied to describe the inflammatory response of a patient to a graft from another person. We are all truly unique individuals and have evolved mechanisms that protect us from invaders, particularly germs, but also from tissue from other animals, including other human beings. 

To a large extent these protective mechanisms depend on blood vessels for "lines of communication". Kidneys, livers, hearts and lungs have many blood vessels and hence grafts of these organs are prone to rejection. The cornea does not usually contain blood vessels so that rejection is much less of a problem.

What happens to rejected corneal graft?

Rejected corneal grafts become inflamed and unless the rejection is reversed the graft function will fail. The graft will become thicker, less transparent and the patient's vision will deteriorate.

There is a misconception that a rejected graft will be expelled from the body leaving a hole which will require emergency surgery. Rejected grafts may opacify but unless the rejection process is complicated in some way, the integrity of the eye is not threatened and it is usually amenable to replacement with a new graft at a later date. Unfortunately re-grafts do not do as well as first grafts in the long term. Corneal graft rejection is therefore best avoided.

Dr R Mills, 2011

(Endothelial Keratoplasty)

Advice for patients 

Why are corneal transplants needed?

The cornea is the clear “watch glass” in the front of the eye. It is the most important lens in the eye and is perfectly transparent and perfectly shaped to focus light on the retina at the back of the eye. If the internal layer of the cornea, called the endothelium, is diseased the cornea becomes cloudy, loses its transparency, and vision is greatly reduced. Under these conditions, it is possible to replace the diseased endothelium with normal transplanted corneal endothelium. 

How successful is corneal transplantation?

Corneal transplantation is the most widely practised and most successful form of transplantation carried out by surgeons. Rejection of the graft, a common problem for kidney, heart, liver and bone marrow grafts, is much less of a problem for corneal grafts.

Rejection is unusual after corneal transplantation because the cornea usually does not have blood vessels. Without blood vessels the body's immune system is less likely to recognise and reject the “foreign” graft. The cornea in patients with endothelial disease does not usually have blood vessels.  

What are the risks?

All operations have their risks and the surgical staff are obliged to tell you what they are - and to inform patients of the risks of not having surgery.

By any surgical standards, corneal transplantation is safe surgery. The most significant risks are those of haemorrhage, infection, glaucoma and retinal detachment. Although these complications occur rarely (about 3 times in 1000 operations) they have serious consequences and could make the vision worse after the operation than before.

The most common risk after endothelial keratoplasty is failure of the graft to adhere in the first 24 hours after surgery. If this occurs the vision is poor and it may be necessary to “rebubble” the graft into position with another air bubble to encourage it to stick. Rarely the graft may need to be replaced if it fails to stick.

Clouding of the lens (cataract) can also occur after endothelial keratoplasty, and thus if any amount of cataract exists before surgery it is common to treat this at the same operation. 

Rejection of the graft can occur, and the risk of rejection is to be assessed for each particular case. Should rejection occur, vision is usually poor and replacing the graft may need to be considered.

When can the operation be done?

The operation is usually done at a time convenient to the patient and surgeon. Few corneal grafts are urgent. Corneal transplantation is most commonly done as an elective procedure. This means that the operation is scheduled and the donor cornea is made available at a pre-arranged time. The Eye Bank of South Australia is located at Flinders Medical Centre and is almost always able to supply a suitable eye for transplantation as arranged. Very occasionally, the operation may be delayed due to non-availability of a donor. 

Only the healthiest corneas from donors are used for transplantation. Eye Banks throughout Australia operate under the strictest guidelines regulated by the Therapeutic Goods Administration. This ensures that only the safest and best quality tissue is distributed to surgeons for transplantation. In spite of this, for reasons that are not entirely clear, a corneal graft may fail to function in less than one in 100 cases.

Anaesthesia

Corneal transplantation can be done under general or local anaesthesia. For the majority of patients a local anaesthetic is preferred. With a local anaesthetic, an anaesthetic solution is delivered by a blunt cannula around the eye to completely remove all movement and sensation.  

Do I need to come into hospital?

No, surgery is usually done as a day procedure. In some cases the patient may be admitted overnight. All patients need to come back to see the surgeon on the day after surgery.

Is the post-operative period painful?

Not usually. There is always some discomfort after any operation but after a corneal transplant the discomfort is minimal. Panadol is usually enough medication to relieve pain.

How often will I need to see the doctor after surgery?

Close follow-up by the surgeon and his or her staff is very important. It can mean the difference between finishing up with a good result or a bad result. Ensuring that the supervision is adequate after surgery is the responsibility of the patient and the surgeon. Usually, patients with uncomplicated corneal grafts need to be seen on the day after surgery, then after a week, and again 4 weeks after surgery. Depending on the patient’s job, 1 – 2 weeks off work is usually advisable. Later they need to be seen at 3 months, 9 months and 12 months after surgery.

What medication will I need?

Following surgery patients are given two different eye drops. One drop is an antibiotic and needs to be used 4 times a day for the first 1 - 2 weeks after surgery. The second is an anti-inflammatory agent and needs to be used 4 times a day for the first 3 months after surgery. After 3 months the frequency can be reduced, but most patients will require one or two drops a day for about a year. 

Will I need spectacles?

Patients usually need to wear spectacles to gain the very best vision. A small proportion will see well without spectacles. Spectacles can often be prescribed 3 months after surgery. 

How long will I need to be followed up after surgery?

Forever. However, after 12 months you will probably only need to be seen once a year. It is important to remember that although you can expect to achieve good vision after surgery, your graft will remain vulnerable to rejection forever. 

Should your eye ever become red or inflamed, or should your vision suddenly be reduced, you must seek professional attention immediately. Early attention to the cause of rejection can prevent graft failure.

There is someone on duty at Flinders Medical Centre 24 hours a day, 7 days a week to attend to patients who have concerns about their grafts.

What is rejection?

Rejection is the term applied to describe the inflammatory response of a patient to a graft from another person. We are all truly unique individuals and have evolved mechanisms that protect us from invaders, particularly germs, but also from tissue from other animals, including other human beings. 

To a large extent these protective mechanisms depend on blood vessels for "lines of communication". Kidneys, livers, hearts and lungs have many blood vessels and hence grafts of these organs are prone to rejection. The cornea does not usually contain blood vessels so that rejection in a corneal graft is less common, but can still occur in any patient at any time for the rest of their life.

What happens to a rejected or failed corneal graft?

Rejecting corneal grafts become inflamed and unless the rejection is reversed the graft function will fail. The cornea will become thicker, less transparent and the patient's vision will deteriorate.

Rejected grafts remain in position but fail to keep the cornea clear, and hence are usually replaced with a new graft at a later date. Unfortunately re-grafts may not do as well as first grafts in the long term. Corneal graft rejection is therefore best avoided.

In addition, corneal grafts rarely last forever even if they never undergo a recognised rejection reaction. This is usually because some of the cellular functions of the transplanted tissue become exhausted and can no longer keep the cornea clear. Fortunately this type of graft failure usually begins years after the original surgery. 

A/Prof  R Mills, 2013

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