Thursday, February 28, 2008

[StemCells] How SCs help Corneal Transplants

'The Eye': Don't believe everything you see
February 25, 2008

"The Eye," Lionsgate/Paramount Vantage films, released Feb. 1.

The premise: Sydney Wells (played by Jessica Alba) was blinded in an
accident with fireworks at age 5. Twenty years later, because of stem
cell research, she is able to undergo bilateral corneal transplants,
which are stitched on with large sutures. At first her returning
vision is blurry, but as it starts to clear, she suffers from
destabilizing visions, hallucinations and dreams. Her
ophthalmologist, Dr. Paul Faulkner (Alessandro Nivola), ascribes her
visions and anxieties to being bombarded with new images without the
knowledge of how to process or assimilate them. Sydney believes she
has acquired the paranormal abilities of her donor.
The medical questions: Do stem cells play an important role in
corneal transplants? Can both eyes be operated on simultaneously, and
are the large sutures depicted in the film realistic? Can vision be
restored after such a prolonged period of blindness? Is there
difficulty in acclimating to sudden vision? Is cellular memory (in
which the donor cells retain characteristics of the donor) possible?

The reality: Adult stem cells are, in fact, used in some corneal
transplants, especially when the blindness is caused by thermal
injury that has damaged the eyes' own corneal stem cells. In such
injuries, the conjunctiva (the mucous membrane covering the white of
the eye) that lies adjacent to the cornea can also be damaged.
Repopulating these conjunctiva cells with adult stem cells could make
the ultimate corneal transplant successful where it failed before,
since the cornea now has more viable tissue to attach to, says Dr.
John Hofbauer, a clinical professor of ophthalmology at UCLA's Jules
Stein Eye Institute.

As for having two transplants at the same time, Dr. Roger Steinert,
director of cornea, refractive and cataract surgery at UC Irvine,
says this is never done. The chance of infection, rejection or poor
healing cause doctors not to risk the second eye at the same time.
Further, the nylon suture used in such surgeries "is almost invisible
to the naked eye. It is only the thickness of three red blood cells."
And whereas Sydney Wells' sutures are removed soon after the
operation, in reality, the sutures are left in for at least six
months.

Some long-blind patients are disturbed by their new ability to see;
others take it in stride. But Dr. Sanjay V. Patel, an assistant
professor of ophthalmology at the Mayo Clinic, adds that return of
normal vision is unlikely after an accident suffered in early
childhood and after so many years. The brain simply becomes unable to
interpret signals from the eye, a condition known as amblyopia.

Finally, neither Hofbauer, Steinert, nor Patel knows of a single case
in which the recipient of a corneal transplant has taken on the
characteristics of his or her donor. This is hardly surprising since
they perform eye surgery not in a horror film, but in the real world.

Dr. Marc Siegel can be reached at marc@doctorsiegel.com.

http://www.latimes.com/features/health/medicine/la-he-
unreal25feb25,1,4178462.column

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StemCells subscribers may also be interested in these sites:

Children's Neurobiological Solutions
http://www.CNSfoundation.org/

Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123

The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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