| |
Ophthalmologists perform over 40,000 corneal transplants each year in the
United States. Of all transplant surgery done today -- including
hearts, lungs, and kidneys -- corneal transplants are by far the most common
and successful. In recent years, the chances of success of this
operation have risen dramatically because of new advances such as the
surgical microscope, finer, less irritating sutures, and better eye banking
techniques. In fact, many patients can expect better than a 90% chance
of a successful and clear
transplant. Even though this surgery is routine for an
ophthalmologist, we understand that eye surgery is a unique and sometimes
frightening experience for you as a patient. We hope that this section
will help guide you through this new experience by answering questions
concerning corneal transplant surgery and your role in ensuring its success.
Defining Terms
Corneal transplant surgery
involves placing a new cornea in your eye. In this operation, your
doctor removes the cloudy cornea and replaces it with another person's clear
cornea. We will use the term corneal transplant surgery, but it is also
called penetrating keratoplasty and corneal graft surgery. Your eye is
the recipient eye because it receives the graft; the other person's cornea
is the donor cornea or donor tissue because this cornea is being donated or
given to you.
What is
the Cornea?
The cornea is the clear front of the eye that covers the
colored iris and the round pupil. Light is focused while passing
through the cornea so we can see. To stay clear the cornea must be
healthy.
Donor Tissue
An eye bank provides the donor tissue for corneal graft surgery.
Eye banks have existed in the United States since 1946, and many
metropolitan areas have an active eye bank , that is often supported by the
local Lions Clubs. With much help from the Lions, thousands of
citizens have been asked to sign pledges indicating that upon death, their
corneas are to be used for transplant operations. Even without the
prearranged pledge, the next of kin may give permission to use eye tissue
upon death. The eye bank receives information regarding the
availability of eye donations, arranges for the collection and distribution
of the tissue, and notifies ophthalmologists with patients listed for
surgery that the operation can be scheduled. There is no charge for
donor tissue, but the costs of operating an eye bank are quite high and
patients receiving corneal grafts are often asked to pay a nominal service
fee to help defray expenses. This fee varies from eye bank to eye
bank. Also, eye banking arrangements differ from country to country.
You can ask Dr. Cano about the eye bank he uses.
You might be curious to know
something about the donor of your corneal transplant; it is the policy of
all eye banks that the donor remain anonymous. Certain general points
might be of interest. If there is no evident abnormality of the
corneal tissue, donors between ages 5 and 75 are considered acceptable if
the tissue has been obtained promptly and is in good condition at the time
of the surgery. Sex, race, blood type, near and far-sightedness, and
eye color are not considered in selecting the donor because they do not
affect the outcome of the corneal transplant surgery.
You might feel uneasy in knowing
that your eye will be receiving donor tissue from another human being.
This should be no more disturbing than having a blood transfusion. Also, as
in the case of transfused blood, the donor tissue is mostly replaced by your
own body cells, so that in the long run, the transplanted cornea is truly
your own.
One of the most valuable
recent advances is the technique for storing donor corneas in fluids for
several days. This protects the donor corneas, allows for better
planning and timing of surgery, and is one of several important factors that
improve chances of successful surgery. Techniques for storing corneas
for much longer periods are now being perfected.
How Can an Unhealthy
Cornea Affect
Vision? If the cornea is damaged it may become
swollen or scarred. In either case, its smoothness and clarity may
be lost. The scars, swelling, or an irregular shape cause the
cornea to scatter or distort light, resulting in glare or blurred
vision. A corneal transplant is needed if:
- Vision cannot be corrected satisfactorily;
- Painful swelling cannot be relieved by medications or special
contact lenses.
What conditions may require corneal
transplants?
- Corneal failure after other eye surgery, such as cataract surgery;
-
Keratoconus, a steep
curving of the cornea;
- Hereditary corneal failure, such as Fuch's dystrophy;
- Scarring after infections, especially after herpes;
- Rejection after first corneal transplant;
- Scarring after injury.
|
