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Cornea transplant
When we see, light enters the eye through the
cornea. The cornea and the lens bundle and steer
the incoming rays of light in such a way that
they hit the right point at the rear of the
eye on the retina. The light-sensitive receptor
cells of the retina convert the light into nerve
impulses and send them through the optic nerve
to the brain. If the cornea has become cloudy
due to inflammations or injury or congenital
degenerative disorders, it is no longer possible
to project a clear image onto the retina. The
problem may also be due to endogenous changes
in the shape of the cornea (keratokonus), which
may occur at a young age and generally progresses
from there. In all of these cases the only way
to restore sight is by replacing the central
cornea sections with donor cornea tissue. Corneal
graft surgery is carried out under local anaesthetic
and usually on an out-patient basis. During
the operation a 7-8 mm slice is taken from the
clouded cornea with a circular knife (trephine)
and replaced by a clear, healthy implant from
the donor cornea. The donor tissue is sewn in
with fine sutures which are removed painlessly
after around 12 months.
A decisive factor in the success of surgery
is the regular therapy with eye drops for a
period of 6 to 12 months after the operation
and a thorough follow-up. The follow-up eye
doctor must make sure that the donor cornea
does not become hazy as a result of being rejected
by the immune system. If such an immune reaction,
which can occur in around 5 % of cases, is recognised
in time, it usually responds well to a drug
therapy. If a severe astigmatism is detected
after the operation, this can be treated within
the first four months by adjusting the stitches.
After a cornea operation, maximum vision is
generally attained after 12 to 18 months. Depending
on the severity of the disorder, the success
rate for cornea transplants is between 70 and
95 per cent.
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