Dear all,
Please find below some information from the ARVO edited by Gislin Dagnelie
Best regards,
Markus

Dear listers,

As I promised a few weeks ago, here is a brief summary of all the things
I learned (or
should have learned, see below) at ARVO, the annual meeting of the
Association for
Research in Vision and Ophthalmology in Ft. Lauderdale. And before you
start getting
jealous (yes, the weather was perfect, 85F during the day and 75F at
night, not a cloud in
the sky, and all that), when you spend 12+ hours a day in an
air-conditioned convention
center where it is downright cold and you're drinking coffee to stay
warm, the meeting
might as well have been in Fargo.

But it is a fascinating overview of all that's new in eye and vision
research, with close to
6000 presentations, and 10500 attendees. The downside of that size is
that it's
impossible to see everything you would like to see, and that you have to
spend at least 1-
2 hours every night to make sure you have your itinerary for the next
day all set up.

It is worth every minute, though. Just in terms of new ideas, potential
therapies,
encouraging findings in animal testing, there is a lot of reason for
optimism. But of
course, as several of you have grumbled, it's always "a few more years."
Well, to start
with something that may have seemed a few years away just a few short
years ago, and is
really here: Growth of the new blood vessels under the retina, the
scourge of wet macular
degeneration is not nearly the certain path to legal blindness it once
was. Eight years ago
everyone was talking about macular translocation surgery as a mrethod to
save sight;
then came Visudyne as a "gentle" laser treatment to stop new blood
vessels, but the idea
that a class of compounds called VEGF inhibitors might actually be used
in the clinic to
stop new blood vessels in their tracks seemed too good to be true.

Yet here they are. Several anti-angiogenic treatments (Macugen,
Lucentis, Avastin) are
duking it out, in clinical trials and in the marketplace, with a lot of
moneyat stake for their
manufacturers. The next generation, drugs that may slow down the
deterioration of
photoreceptors in RP and dry AMD, is here: We've all heard about the
next Neurotech
trials, so if all goes well such treatments will be a real option soon.
How well and for how
long the degeneration process can be stalled we don't know, and lost
photoreceptors will
not come back, so chip implants and cell transplantations remain important.

As for the chip implants, the Optobionics trial is on-going, and we can
expect to hear more
about its results later this year. If all is well, the effect of this
implant will be similar to that
of the Neurotech implant: slow down the degeneration process, and
possibly improve
vision by a modest amount. More exciting was the news from two German
groups who
have recently performed their first chronic iimplants in blind RP
patients. Both confirmed
that the patients see phosphenes similar to those described by the
Second Sight implant
wearers, so we now have independent confirmation from 3 groups that a
chronic implant
can create at least some vision. All three groups indicate that they
expect more, and
more detailed, results to be available soon. Second Sight is still
announcing its next
generation implant for later this year.

There were many presentations regarding stem cell transplants, almost
all of them in
rodents. Some of these used stem cells obtained from within the eye, or
from the
umbilical chord, but most used stem cells obtained from bone marrow
(either autologous,
i.e., from the same animal or patient, or heterologous, i.e., from an
animal without retinal
degeneration). My impression (but I admit that it may be biased by my
expectation) is that
all stem cell methods have similar results: temporary vision
improvement and better
health of the retina in the transplanted eye, that can most likely be
explained by an indirect
effect of the transplanted cells on the native rods and cones,
supporting their remaining
function.

The same limitation seemed to hold for most transplant reports with
fetal or adult retinal
cells, although a few of these studies may have shown signs of the
transplanted cells
making functional connections, and possibly creating new vision. The
most exciting
report, at least among the ones I saw, was from the Institute of
Ophthalmology in London,
where researchers transplanted developing rods harvested from a
normally-sighted
mouse at about 5 days after birth (which is before the mouse opens its
eyes, but well after
the cells have moved into their final locations), transplanted them into
the degenerated
retina of an adult RDS mouse, and demonstrated quite convincingly that
the transplanted
cells formed working synapses (i.e., contacts) with secondary cells and
other features
demonstrating they were fully functioning as photoreceptor cells. The
particular stage of
development when the cells were harvested would correspond with that of
the human
retina a few months before birth. Of course this raises questions about
the potential
availability of such donor material for human cell transplantation, but
it may just be enough
to know what the ideal development stage is, i.e., after the cells have
transformed from
stem cells into developing photoreceptors, and then create cells in that
stage of
development in tissue culture.
More important is the question how much flexibility there is in the
age of the recipient: In
mice it appears that the transplanted cells can thrive even after the
native photoreceptors
have degenerated, but for the much slower degeneration process in human
patients this
may not be true. If the technique only works in young children or
persons in an early
stage of retinal degeneration, that would rule out a lot of patients who
are not diagnosed
until the degeneration process is well under way. But since the process
is localized, it
may be possible to perform the transplants in retinal areas where the
rods and/or cones
are still in relatively good shape.

Hope this helps, and that you will see it as a glass at least half full,
rather than almost
empty. Looking back 5 years, much of what I saw this year was still in
the realm of ideas,
or even fantasy, so I think there is much to be excited about.

Gislin
------
Gislin Dagnelie, Ph.D.
Associate Professor of Ophthalmology
Lions Vision Research & Rehab Center
Johns Hopkins Univ. Sch. of Medicine
550 N. Broadway, 6th floor
Baltimore, MD 21205-2020 USA

E-mail: gislin@... It's a small world after E-mail!




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