What is a Cornea?
The cornea is the transparent portion of the eye which
allows light to enter and performs 2/3rds of the
focusing tasks. The cornea also covers both the iris
(the coloured portion of the external eye) and the pupil
(the reactive ‘light meter’ in front of the lens). There are
no blood vessels in the cornea, but there are nerves.
Nutrients for the cornea are supplied by the same
source as the tear-ducts and internal eye fluids.
The cornea allow lights to enter the eyeball, and the
cornea’s convex shape focuses that light towards the
pupil and another structure called the lens. In essence,
the cornea performs the broad brushstrokes of vision,
while the shape-shifting lens performs the fine details
before all of the light hits the retina. It is the shape of
the cornea’s dome which determines whether or not a
person may be nearsighted, farsighted or astigmatic
(Distortion of the Cornea).
During vision correction procedures, external lenses
may be used to re-focus images in the eye’s lens or
the shape of the cornea may be modified. Contact
lenses placed directly on the cornea change its
thickness, creating a new focal point. Some advanced
contact lenses use tension to reshape the entire
cornea, allowing near-normal vision until the cornea
resumes its original shape and the blurriness returns.
What is Corneal Transplantation?
This is the procedure whereby abnormal tissue is
replaced by a healthy donor cornea. It has been
performed for over 100 years and is the most common
and most successful of transplant procedures. It may
be:
• Full thickness: penetrating keratoplasty (corneal
transplantation)
• Partial thickness: lamellar or deep lamellar
keratoplasty (corneal transplantation)
A corneal graft is a transplant operation.
Although the operation itself is often reasonably
straightforward, the recovery period often takes a long
time and this information is to help you to understand
what to expect. It is not however possible in an
information leaflet such as this to
provide specific information that is accurate for all
patients’ circumstances. The doctor looking after you
will give you additional information based upon your
own condition.
Why do you need this operation?
The usual reason for performing a corneal graft is to
help you to see better. For some people, however, the
operation may be advised to help in the treatment of
chronic pain and irritation in the eye.
In that case, the operation may be worthwhile even if it
does not greatly improve your vision. Rarely, the
operation may be advised in order to save the eye, for
example if there is very severe corneal ulceration. It is
very important that you understand why it is being
recommended in your case, and what it is hoped the
operation will achieve for you.
Where does my new cornea come from?
Your cornea will have come from someone who has
expressed a wish that their corneas be used to help
someone else to see, after their death. People who
offer their organs in this way are called donors, and
transplant operations would not be possible without
their generosity. The donor’s cornea will have been
thoroughly tested and kept in an Eye Bank for a period
of time, before being sent to the hospital where the
operation is to be carried out.
The Eye bank is responsible for ensuring that your new
cornea is in good condition, and also performs checks
to try and ensure that your risk of catching an infection
is limited.
The operation itself
This is usually done under a full (general) anaesthetic
although if your general health is poor, it may be
possible to use local anaesthetic. It takes between 1-2
hours. During the operation, the surgeon removes a
circular piece of your cornea and replaces it with a
similarly sized piece of the donor’s cornea, which is
stitched into place. In some cases other procedures,
such as cataract extraction may be done in
combination with the corneal graft. These may
increase the duration of the operation.
You will awaken with some soreness in the eye and a
protector taped over it. Your eye will not be bandaged
up. You will be allowed up and about after the
operation. You may be allowed home the same day or,
if not, 1 to 2 days later.
After the operation
Pain after a corneal graft is seldom severe and can be
expected to settle quite quickly. The improvement in
vision, however, is often rather slow.
This is because the cornea takes a long time to heal
and as it does so, shape changes in the cornea lead to
changes in the way it focuses light. It is unlikely that
your vision will be “stable”, i.e. worth prescribing new
glasses or contact lenses, for at least 6 months after
the operation, and in some people it can take a year or
more.
Stitches
The very tiny stitches (properly called sutures) that are
put into the cornea hold the graft in place but also
affect its shape and therefore, the way the eye
focuses. They are not dissolving sutures and will
eventually need to be removed. Two main patterns of
suturing are used – interrupted (or individual) suturing
and continuous. Some surgeons use both methods
combined.
In some patients, it becomes apparent after the
operation that the sutures are causing sufficient
distortion of the cornea (astigmatism) for it to interfere
significantly with the quality of vision. It may then be
necessary to adjust or remove sutures. Adjustment
may be done in the clinic or in the operating theatre,
depending upon circumstances. It enables the cornea
to sit more snugly in place, allowing it to focus better.
The exact timing of suture removal varies greatly
between individual patients and has to be decided on
an individual basis. Removal of sutures too early after
the operation could result in the graft coming apart and
requiring resuturing. Eventually, however,
approximately 12 to 24 months after the operation, all
your remaining sutures will be removed.
Seeing clearly after the operation
You are most unlikely, after a corneal graft, to be able
to see perfectly without some assistance.
All corneal graft patients have some degree of
distortion of their cornea (astigmatism) which needs to
be corrected, usually with spectacles, for them to see
clearly. Some patients have large amounts of
astigmatism, or are rather long or short-sighted, in the
eye that has been grafted.
They may need to wear contact lenses for the best
level of vision, or to avoid clashes between their two
eyes.
However, a small proportion of corneal graft patients
(around 10%) need to have a further operation on their
corneas, in order to improve their focussing, and
enable them to see better. There are three main
different types of this ‘secondary refractive surgery’
• keratotomies (‘‘relaxing incisions’’)
• resuturing (i.e. replacing sutures or putting extra
ones) and lamellar surgery with the excimer laser
(LASIK).
A full discussion of them is outside the scope of this
document.
Grafts, work and activity
After a corneal graft, your eye is at first very vulnerable
to blows on it and to the effects of severe straining
(bending down, pushing or lifting).
You should not take any more exercise than a brisk
walk for the first month after the operation. You should
avoid lifting heavy objects, and if you have to bend
down, do so slowly from the knees, keeping your-head
up. It’s a good idea to get help with hair washing, and
you should do it with your head back, avoiding
shampoo in the eye.
You should wear an eye shield at night until you are
used to not sleeping on the side of the operated eye.
It is a good idea to wear glasses or sunglasses simply
for protection, even if they don’t help the vision. Above
all, don’t poke or rub the eye!
If you do a desk job, you can usually go back to work
after about 2 weeks, but if your job is more strenuous,
you will be advised to stay off work for at least 4
weeks, or in some cases even longer.
If you drive, you can usually start again after your first
check-up, provided that the vision in the other eye
remains satisfactory.
Once home, normal bathing and showering can
resume but care must be taken not to get water in the
eye for a month.
If the eye gets sticky, gently wash with cooled, boiled
water. Eyelid make-up should also be avoided for this
time.
Sunglasses can minimise discomfort but contact lenses
should be avoided for at least 8 weeks – the patient
should talk to their surgeon before resuming wear.
It is very important that the patient does not rub their
eye in the early weeks post-operatively.
Additionally, an eyeshield will be given to the patient to
wear whenever they sleep or have a nap, for several
weeks, to avoid inadvertent rubbing of the eye.
Swimming should be avoided for at least 4 weeks.
Light work can be resumed in 2-3 weeks and manual
labour in 3-4 months.
If you play sports, it is essential to wear eye protection
at all times after a corneal eye graft. Eye protectors
for racket sports are available in sports shops. If you
swim, you should wear goggles (primarily for protection
from injury, not contact with water) and you should not
dive in.
If you play football, there is a small risk of serious
injury, particularly when heading the ball. Again you
should consider eye protectors. You are strongly
advised not to play major contact sports such as
rugby, judo etc. at any time after a corneal graft, and
not to recommence sports until you have been told that
it is safe to do so.
In the long term, a corneal graft is strong enough to
stand the rigours of ordinary life, but an eye with a
corneal graft is never as strong as a normal eye and
may be split open by a severe blow such as a punch in
the eye. Such an injury can cause blindness.
Treatment and supervision
Everyone must use steroid eye drops after the
operation. These are necessary to ensure that your
eye does not get too inflamed, which would cause you
pain and damage the graft. Steroid drops can have
side effects, which must be watched for. They can
cause pressure rises inside the eye, they reduce
resistance to infection and, with very prolonged use,
can cause cataracts. Therefore it is very important that
you are examined regularly to monitor the treatment,
and that you report promptly to your doctor if you think
you have a problem. The steroid drops are slowly
reduced in strength and frequency and are usually
stopped approximately 12 months after the operation,
although some people may need to use them for
longer.
Most patients can expect to attend Outpatients
between 8 and 10 times over the first year after a graft,
with gradually increasing gaps between appointments.
Patients are generally kept under review for several
years after the operation.
Possible complications of the operation
There are risks attached to any operation, involving the
operation itself and the anaesthetic given in order to
carry it out. These are some of the most important
risks of corneal grafts.
Minor complications happen from time to time but do
not usually affect the result. They include brief periods
of raised pressure or leaks of fluid between the stitches
from within the eye. These generally settle within a few
days of the operation. However, occasionally, it is
necessary to replace a stitch or put in an extra one, if a
leak doesn’t seal up on its own.
Major complications of the operation itself are rare, but
when they occur they can threaten sight or even
possibly cause the loss of the eye. They include
bleeding within the eye and infection entering the eye.
They may require further operations if they occur.
Disease transmission is a possible complication of
any transplant – in other words, the recipient could
possibly catch a disease from the donor.
All corneal donors are tested for the viruses that cause
hepatitis and AIDS. However, there is no test which will
detect the germ which causes Creutzfeld-Jakob
disease (CJD) and unknown viruses may also exist for which there is currently no test. The risk of catching
such a disease is unknown, but likely to be very small.
Rejection is a major complication, which can affect
any transplant. It happens when your body detects that
a piece of tissue from another person has been put
into you, and your immune system then tries to destroy
it. About 1 in 7 patients who have a corneal graft will
have a rejection attack at some stage, although some
patients are at a much greater risk than others.
Rejection can start as soon as 2 weeks after a graft
but is most common several months afterwards, and
may occur years later. The quicker rejection is
diagnosed, the better the chance of recovery.
If your eye gets red, watery, gritty, develops cloudiness
of the vision then rejection may be the cause and you
are advised to attend your eye casualty department
immediately. If rejection is found, it is treated with very
frequent, strong steroid drops, and occasionally with
steroid tablets or drip feeds. Most corneal grafts do
recover from their rejection attack, but a lot of patients
will need to go on with the steroid drops for a long time
afterwards, sometimes permanently. Patients who are
in the “high rejection risk group” may be advised to
have a “tissue matched” graft. However, some patients
have to wait a long time for a suitable cornea to
become available. Tissue type is determined by a
blood test. The degree of benefit from tissue matching
is unclear but is the subject of further research at
present.
Causes of failure of corneal transplants
A failed corneal transplant generally looks cloudy and
dull, making the vision very blurred. This list gives the
commonest reasons why a corneal transplant may
eventually fail. Most patients with a failed transplant
can be offered another one, but individual
circumstances will dictate what is recommended in
each case.
Rejection (discussed above) may lead to failure of
transplant, which may happen immediately or
sometimes may happen some time later.
Failure of the endothelium (or decompensation)
means that the graft no longer has enough cells on its
inner surface to keep it clear, and so it must be
replaced.
Recurrence of the original disease can happen to
people whose corneal graft was done because of a
genetic disease (corneal dystrophy) or an infection
(viral keratitis).
Infection causing ulceration leading to scarring, may
occasionally cause graft failure.
Unacceptable refractive result means that the graft
cannot be made to focus satisfactorily for its recipient,
perhaps because of marked astigmatism. Such a graft
may have to be considered as a failure, and replaced.
Deep Anterior Lamellar Keratoplasty (DALK)
(Lamellar Transplant)
Your surgery will be carried out by a Consultant who is
suitably experienced and qualified.
A DALK is a partial thickness graft of the cornea in
which we replace the front 95% of the cornea and it is
used as an alternative to penetrating keratoplasty (PK),
which involves a full-thickness corneal graft.
By preserving that part of the cornea that is healthy,
the risks of graft surgery such as graft rejection,
bleeding and infection inside the eye, are decreased.
In this case, the tissue preserved is the back 5% of the
cornea including a layer called ‘‘Descemet’s
membrane’’. After removing the unhealthy part of the
cornea, a donated cornea is stitched into place and the
sutures remain for approx 12 to 18 months.
What are the risks?
The risks of the surgery include, but are not limited to:
• Infection
• Bleeding
• Non adherence of graft
• Loss of Vision
• Graft Rejection
• Increased pressure inside the eye
• Conversion to full thickness graft (Penetrating
• Keratoplasty)
• Cataract formation
• Recurrence of the original problem
NB. Please also be aware that you may need to use
glasses or contact lenses after you have had surgery.
Although we have discussed with you the purpose and
likely outcome of the proposed procedure, it is not
possible for us to guarantee a successful outcome in
every case. Should any of the above complications
occur, you may require further surgery.
What are the benefits?
Replacing the abnormal corneal tissue with healthy
donor tissue should improve the visual potential
of the eye and also where the cells of the cornea are
damaged (dystrophies), this will improve the comfort by
decreasing occurrence of ocular surface breakdowns.
Are there any alternatives to surgery?
In the case of keratoconus, possible alternatives are
the continuation of contact lens use, or the implantation
of semicircular plastic rings (INTACS) inside the
cornea, a less invasive procedure, to change the
shape of the cornea.
In corneal dystrophies, possible alternatives are laser
surgery (PTK/PRK) to reshape the surface of the eye
and remove some of the abnormal tissue, or
conservative treatment with bandage contact lenses
and eye drops. If you have any specific concerns, you
should discuss them with your surgeon before the
operation.
Endothelial Keratoplasty; Descemet Membrane
Endothelial Keratoplasty (DMEK)/ Descemet
Stripping Automated Endothelial Keratoplasty
(DSAEK)
If the corneal endothelium is damaged and the cornea
is water-logged but otherwise clear, e.g. Fuch’s
dystrophy, then penetrating keratoplasty or endothelial
keratoplasty may be used. Endothelial grafting is the
preferred choice in most cases of endothelial failure
because of its relatively rapid visual recovery. If your
cornea has both damaged endothelium and corneal
scarring, penetrating keratoplasty is necessary. This is
a more recently developed procedure that involves
only replacing the innermost layers of the cornea,
rather than the whole cornea as in a Penetrating
Keratoplasty or Full Thickness graft.
In conditions such as Fuchs endothelial Dystrophy, the
innermost layer, the endothelium is diseased. The rest
of the cornea is normal. Previously to replace the
valuable endothelial layer, the whole central cornea
was replaced by performing a Penetrating
Keratoplasty. With innovative techniques, we are now
able to replace just the innermost layer. The procedure
involves peeling off the inner two layers of the
diseased cornea. A donor cornea is then split or
dissected to create a flap of the inner two layers and
sometimes a small portion of stroma (to provide
substance for manipulation).
This thin donor is then folded and inserted into the eye
and floated up to stick onto the inside of the cornea,
replacing the layers removed earlier.
One of the most challenging aspects of DMEK/DSAEK
surgery is creating a reproducible donor layer. This can
vary considerably, and could result on cancelling the
surgery, and rescheduling it for another date.
About the procedure
DMEK/DSAEK is a technique where the endothelial
cells are removed from your eye and selectively
replaced with a new layer of endothelial cells. These
new cells are held in place temporarily by a bubble of
air inside your eye. In the past, a full thickness corneal
transplant has been the preferred technique. However,
this procedure requires stitches, and a full thickness
wound which will remain weak and results in a
prolonged recovery time. Since surface corneal
incisions and sutures are not used in this more modern
technique (DMEK/DSAEK), the corneal shape is
preserved which allows a more rapid visual recovery
than a full thickness corneal graft. The procedure is
technically challenging, however can be accomplished
very quickly often with very few stitches. The
procedure is becoming more and more popular and
will in time become the Gold Standard.
What are the risks?
• Graft detachment/dislocation
• Temporary increased eye pressure
• Graft failure, which will require further surgery
• Graft rejection
• Blurred vision due to macular oedema (swelling • of
the central part of the retina)
• Retinal detachment
• Eye infection with loss of vision – very low risk
After the operation You will be asked to lie flat face up
as much as possible for 1 to 3 days after surgery, as
we usually leave an air bubble in the eye to push the
new endothelial graft in position. This air bubble is
usually absorbed within 48 hours. You will be given two
lots of drops (an antibiotic and a steroid) to use, at first,
every two hours during the day. The dosage and
frequency of these will be reduced gradually, as
prescribed by the corneal surgeon. Your vision will be
misty for a few days after surgery, but it will improve
over the next 3 to 4 months, as the cornea gradually
clears.
Resuming normal activities
Work – You are likely to need 2 weeks, or longer, off
work, depending on the type of job you have. Sport/
hobbies – We advise that, should the surgery be
successful, you wait for 4 weeks before returning to
sport or active hobbies.
Flying – Air travel is usually permissible 3 days
following surgery, providing the air bubble has been
absorbed into the eye, as previously described. If a
special gas other than air used, then this period might
be longer. This needs to be discussed with your
surgeon before making any travel plans.
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Author Opthalmology Department
Approved by Opthalmology Governance Meeting
Date of Publication 22/01/2025
Reference No PL/171 (v2)
Review Date 01/01/2028
