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>> Brandi Dean: Good morning.
Welcome to Mission Control Houston.
As I promised, we have here with us Dr. Christian Otto,
who is the principal investigator
for the ocular health experiment
which flight engineers Rick Mastracchio and...
is helping Mike Hopkins with today.
And he's going to tell us a little bit
about what's been going on with that experiment,
what it's about, and what some
of the results they've started seeing are.
Thanks so much for joining us.
>> Dr. Christian Otto: Yeah, thanks, Brandi.
As you may know, as you may know,
the ocular health experiment was instituted
because of the eye problems that were documented
in a number of crew members.
As you may know, up to 50 percent
of crew members have changes
in their vision following their space flight.
And in 2005 we found a rather concerning eye problem
which is swelling of the back
of the optic nerve as it enters the eye.
And this is actually quite a serious problem.
In fact, we see it in many diseases
such as glaucoma and head trauma.
It can be a sign of elevated intracranial pressure,
and if this does not resolve it can actually lead to blindness.
And after some investigation,
there's actually been six crew members now
who developed this serious finding,
but there have been other findings, as well,
such as changes in the structure of the eyeball itself,
it's been somewhat compressed in many crew members,
and also widening of the covering
of the optic nerve behind the eye.
Both of these findings are actually suggestive
of elevated intracranial pressure.
So this is of concern to the program, particularly
with future longer-duration missions.
>> Brandi Dean: That makes sense.
Do you have any theories about what's causing it
or why we're seeing that?
>> Dr. Christian Otto: Yeah, that's a very good question
and one of the leading hypotheses is the cephalad
fluid shift.
So this is -- here on earth, we have gravity acting
on our fluids; fluid is drawn toward the lower part
of the body.
But in space flight, it actually gravitates more toward the head,
as you see here in the video that we're showing.
You can see that fluid tends to move upwards in weightlessness,
and one of our concerns is that this may lead
to elevated intracranial pressure.
And you can see that fluid
around the brain actually communicates with the back
of the eye through, around the optic nerve,
which is also surrounded by the sheath,
and you can see this with the blue arrows.
And if the pressure increases, it can actually widen the back
of the optic nerve sheath and push on the eyeball.
And this is why we see this compression
of the eye, as you can see here.
And these pressure differentials can cause changes in vision.
And we can measure vision by refractive change or diopters.
This has to do with the optical power of the eye.
And these changes result in a degradation of near vision.
>> Brandi Dean: Okay, so that's what we think is kind
of causing it, I guess.
What is the crew member, what are the crew members doing
on board the Space Station to help get us more information?
>> Dr. Christian Otto: Yeah,
so as part of the ocular health experiment, we have a number
of tests that we're conducting.
This is also part of the medical ops data collection, as well.
But things you might get done in your family doctor's office
or if you go to the optometrist or ophthalmologist.
We're doing fundoscopy.
Fundoscopy ops are going on today, I believe,
in Mike Hopkins and Koichi Wakata,
where we're taking pictures of the back of the eye.
This is as though you were at the doctor's office
and they're looking at the back of your eye
with an ophthalmoscope, but this has a much more higher
resolution and we can look at the vessels of the eye,
the retina and the optic nerve.
We're also doing ocular ultrasound.
This allows us to look at the structures of the back
of the eye, measure that compression
if it's occurring, and the widening.
And there's a new device
on station now called ocular coherence tomography.
It's a very powerful ultrasound device that lets us look
in very fine detail at the retina and the optic nerve
to see swelling long before we can see it
with an ophthalmoscope.
So this allows us to more carefully monitor crew members,
whether they're headed toward these findings.
We're also measuring intraocular pressure,
so taking a pen-like device and this taps on the eye
and we can measure the pressure in the eye
because we think the differential
between the pressure in the eye and the pressure
in the brain may also be a causative factor
in this problem.
>> Brandi Dean: And this is all stuff that the crew can kind
of do amongst themselves without help from the ground?
Or I guess they get talked through it, but.
>> Dr. Christian Otto: Yeah, and that's a great question.
And in fact, that the crew members are obviously extremely
talented and skilled, yet many
of these are very sophisticated medical tests.
So there's a large team of folks here on the ground,
biomedical controllers, we have subject matter experts
who actually guide the crew
through many of these procedures.
So they're sort of the eyes and the crew are the hands
and they help them through many of these tests
to acquire these medical-grade images.
So it's a team effort.
>> Brandi Dean: Okay, and so far are they doing a good job
of getting the information for you?
>> Dr. Christian Otto: Yeah, you know, in fact, we have data
from two crew members now and they've done a wonderful job
in collecting this very sophisticated data
across many different tests.
And this is actually helping us understand this problem
much better.
>> Brandi Dean: Okay, great.
Well, so as you get a better understanding, any ideas --
is it something you're going to be able to prevent
or is it something you just accommodate
on longer-duration missions?
>> Dr. Christian Otto: Yeah, and another great question.
So the concern is for longer-duration missions,
so as you're alluding to, the goal here is to come
up with treatments and countermeasures
to prevent what we think may be happening.
And, again, our leading hypothesis is the cephalad
fluid shift.
So some of the possibilities are mechanical factors
that help draw some of that fluid back towards the legs.
And the Russians use a device called the brazlet [phonetic],
which is essentially a tourniquet
around each thigh that's calibrated.
And that helps keep some of the venous blood in the legs
and preventing some of that cephalad fluid shift.
That's a potential countermeasure.
There's also a negative pressure suit.
There's both a U.S. version and a Russian version
that is basically like a large set of pants that you put
on that creates a negative suction and draws fluid
down towards the legs.
That might not be a perfect option in the future,
but there may be other versions that aren't quite as cumbersome.
Other things that we're considering are drug treatments
and so on.
So the experiment's giving us insight
into what countermeasure we might be able to employ.
>> Brandi Dean: So will these experiments go
on a long time before we start seeing some
of the countermeasure-type experiments or is
that coming in the near future?
>> Dr. Christian Otto: Yeah, and another great question.
In fact, following closely on the heels
of the ocular health experiment is the fluid shifts experiment,
another NASA experiment,
combined with other outside investigators, that were sort
of an occupational or observational study to look
at what's happening to the crew member.
We're not using any interventions to see
if we can change what's going on,
but the fluid shifts experiment will employ the Russian Chibis
suit, which is a negative pressure device that's actually
on board on the Russian segment.
So this is an exciting collaborative experiment
with our Russian colleagues.
And to actually look at these changes,
and the changes we're seeing in the crew now,
can they be reversed using, for example,
the Chibis negative pressure suit?
So that will give us a clear indication
if that's a viable counter-measure.
>> Brandi Dean: Okay, well I'm sure we'll be hearing more
from you about that soon.
In the meantime, is this something
that could help us here on earth or is it just for people
who are going to space?
>> Dr. Christian Otto: Yeah, and that's another great question.
And, you know, with this problem,
the visual impairment-intracranial pressure
problem, we're really on the cutting edge of several areas
of clinical and medical science here on the ground.
For example, understanding diseases of the eye
that involve intraocular pressure and the difference
between intraocular and intracranial pressure,
such as glaucoma, better understanding diseases
that lead to papilledema.
Also diseases that involve circulation
of cerebral spinal fluid in the brain,
such as idiopathic intracranial hypertension or hydrocephalus.
Another exciting thing is the development of new technologies
that will play a critical role in medicine on earth,
such as ways to measure intracranial pressure
without drilling a hole in someone's skull
and putting in a device.
This is very exciting with huge implications for, you know,
head trauma and neurosurgery and neurology; and also ways
to measure diseases of the eye, such as ultrasound,
which many of these techniques are being pioneered right here
at NASA.
>> Brandi Dean: Sounds like it could be good news
for a lot of people.
>> Dr. Christian Otto: Definitely.
>> Brandi Dean: Well, thanks so much
for coming and talking with us.
We really appreciate it and...
>> Dr. Christian Otto: My pleasure.
>> Brandi Dean: ...with that said,
I'm sure we'll have you back to give us more updates
as the experiments go on.
>> Dr. Christian Otto: Thank you.