By John F. Henahan
ATHENS - Transplantation of human amniotic membrane
is a useful tool for improving the management of
severe external diseases of the eye, Anastasios John
Kanellopoulos, MD will tell the 3rd ESCRS Winter
Refractive Surgery Meeting here.
The procedure, which was pioneered by Shaeffer Tseng,
MD, Bascom Palmer Eye Institute, Miami Florida is
particularly useful for managing pemphigoid, chemical
burns of the eye and other severe external eye diseases
either alone or in combination with penetrating keratoplasty
and conjunctival allografts transplantation, said
Dr. Kanellopoulos, Hellenic Eye Center "ORASIS",
Athens Greece. He is also a member of the Cornea
Transplant Service and resident education at the
Manhattan Eye, Ear and Throat Hospital, New York
City.
"The reason we chose to work with the human amniotic
membrane, which is processed by Bio Tissue, Florida
USA, is that at the present time, there are few successful
and safe alternatives for the management of these
severe external eye diseases. Its advantage is that
it provides two useful substrates which assist in
the reconstitution of the damaged eye surface," he
told EuroTimes in an interview.
"The basement membrane creates a scaffold on which
the corneal epithelium is able to grow and re-epithelialise
the eye surface when it has been weakened by pemphigoid
or other diseases. In addition, the "sticky" stromal
underside of the membrane contains biological suppressors
of a variety of tissue-growth factors which ordinarily
induce the proliferation of the fibroblasts which
contribute to scar formation " from the patient's
other healthy eye. I have also used it in combination
with penetrating keratoplasty and in one case as
a primary procedure for reconstructing the corneal
epithelium. For example, I have used it successfully
along with keratoprostheses to help manage persistent
epithelial defects," Dr. Kanellopoulos said.
"Dr. Tseng primarily uses the amniotic membrane
transplants along with conjunctival allografts, using
tissue taken from closely related donors, while I
have been using it as well along with conjunctival
allografts taken.
In Athens he will be reporting on the outcome of
eight patients with pemphigoid and herpetic keratitis
disease with severe dry eye disease and persistent
epithelial defects and who have been followed for
up to twelve months. The procedure involves loosely
suturing the semi-translucent amniotic membrane to
the corneal surface and is quite easy to perform,
he noted.
"Usually if the external disease is really severe,
I prefer to reconstitute the surface with the conjunctival
autograft or penetrating keratoplasty and then place
the amniotic transplant over it. That was how we
managed one patient with severe herpetic disease
and a perforated cornea. In order to address the
external disease, which the corneal transplant did
not, we placed the membrane on top of the graft and
the patient did not develop an epithelial defect
on the graft. To me, that was quite impressive.
Alternative to
Tarsorraphy?
"You can't really see what is going
on after the amniotic membrane has been placed, but
after it has dissolved away, usually within two or
three weeks, you can invariably see that the surface
has been well re-constituted. All three patients
with neurotrophic herpetic disease had no problems
with the epitheli- um after transplantation of the
membrane. To get that kind or result, you would ordinarily
have to do a tarsorraphy or place a punctal plug,
which can be much less comfortable for the patient," Dr.
Kanellopoulos told EuroTimes.
"In our patients the anatomical results
have been very good. As for visual reha- bilitation,
it depends on the underlying disease. For example,
if you are dealing with a patient with glaucoma or
age related macular degeneration, you don't just
have the surface problem, and the other conditions
will reduce expectations for a good visual outcome."
"Although our sample is admittedly
small, we haven't seen any complications associated
with the procedure. A small disadvantage is that
some patients who are very demanding, may not be
happy that the eye has a somewhat clouded appearance
after the membrane has been transplanted, but that
is a transient problem. Otherwise, our patients are
quite happy with the results.
"Perhaps another disadvantage is the
cost of the membrane. It is shipped to us in a container
at -70" C, and must be treated to remove any possible
contaminants. It is also extensively screened for
HIV, syphilis and hepatitis B viruses, all of which
involves considerable testing, nevertheless. The
remarkable clinical results that can be achieved
make the effort and expense worthwhile in my opinion," he
concluded.
Dr. Kanellopoulos is also Assistant
Professor of Ophthalmology at the State University
of New York.
Source: EuroTimes,
Volume 4, Issue 1, Jan-Feb 1999
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