
The syndrome impairing astronauts’ eyesight - markmassie
https://www.washingtonpost.com/national/health-science/the-mysterious-syndrome-impairing-astronauts-eyesight/2016/07/09/f20fb9a6-41f1-11e6-88d0-6adee48be8bc_story.html
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andrewtbham
It will not prevent travel to Mars. It's effects can likely be countered.
Perhaps by artificial gravity.

[https://en.wikipedia.org/wiki/Artificial_gravity](https://en.wikipedia.org/wiki/Artificial_gravity)

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PhantomGremlin
Not everyone is ready to admit it yet, but IMO there is no long term future
for us in space without something like artificial gravity.

I remember back in the 1970s one of the Skylab astronauts came to my college
to give a talk. I had read about some problems, so I asked him about the
effects of prolonged weightlessness. He was very dismissive, he vehemently
denied that there could be any problems at all.

As they say, denial isn't just a river in Egypt. And the denial has been going
on for many many decades.

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jerf
Artificial gravity is easy. You "just" spin things.

The tricky bit is being able to launch enough mass to build something safe and
comfortable to spin; there's a limit to how small you can make your spinning
habitat before the difference between "centrifugal force" and gravity is too
pronounced for our long term comfort. That's part of why making it cheaper to
launch per unit mass is so important. If we could put ten times the mass in
space for the same price, the ISS would probably look quite different.

I'm of the same opinion as you in general; what spending years in zero-g has
proved is that it's not long-term viable. There's too many ways in which it is
not viable to expect us to be able to fix all of them, when indeed it's not
clear we can fix _any_ of them with drugs or anything short of massive genetic
engineering. We don't know how much gravity is necessary, though I'm inclined
to guess closer to .5G than .05G. Once you get enough mass in space, though,
that's not really that difficult.

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ams6110
Now all your space vehicles need to be able to hold together under 1G of
force. That means a lot more structure and mass and the cost goes way up.

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JoeAltmaier
How about sleeping in a centrifuge? No need for the entire spaceship to spin.

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nxzero
If it was possible to build a gravity sleep chamber, it's very possible that
exposing the human body to gravity and zero-gravity on a daily basis would be
put more, not less stress on a body than zero-gravity alone.

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JoeAltmaier
That's just a random guess. We already lay down for 8 hours and stand up for
16. My random guess is, our fluids would recover with at least some artificial
acceleration and why not when sleeping?

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rbanffy
If you intend to replicate the effects of standing, you'd need to sleep
standing.

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wizardhat
Studies going as far back as the 80s show that people in submarines develop
myopia:

[http://www.ncbi.nlm.nih.gov/pubmed/7457562](http://www.ncbi.nlm.nih.gov/pubmed/7457562)

The leading theory is that being in a confined space causes the eye to adapt
to viewing things up close rather than at a distance.

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mtreis86
Anecdote: I saw an article about Native Americans, using a technique of
quickly focusing from near to far and back as a means to increase their
eyesight range, when I was around twelve years old. Called Eagle Eyes, or
something. I have been practicing regularly for eighteen years now, and my
eyesight has only improved. I have been looking at computers and books at
least a third of my time since. Am I actively preventing myopia? Interesting.

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whuuu3
That's really interesting. What were your prescriptions before/after?

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mtreis86
I was 20/20 in both eyes before, 20/15 in one and 20/10 in the other now. The
last measurement was two years ago.

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Terretta
Are you over 40-45, or under?

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Gracana
"The only proven methods of measuring intracranial pressure are invasive: the
spinal tap or drilling a hole into the skull."

Sounds like we need to test/prove something new. I did some searching for a
wireless intracranial pressure sensor and didn't find anything, but I bet you
could make one. The sensor could be a pair of capacitor plates on the inside
of a sealed cavity in a flexible material, with an antenna attached, such that
the capacitance changes as the cavity is squeezed by the pressure around it.

To make a measurement, you'd use an external antenna to hit the sensor antenna
with an impulse, which would cause it to ring at a frequency proportional to
the pressure it's monitoring.

Very simple, no batteries, could be made very small...

[edit] Oh hey, they mention implanted devices. I guess I should have finished
reading the article before posting.

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tines
So what I'm hearing is that we should send myopic people into space to fix
their vision!

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fractx
Only in theory. The induced hyperopic shift from axial length reduction of the
eyeball would likely be reversible after the patient's intracranial pressure
is brought back down under control. Moreover it is nearly impossible to find
the sweet spot for just the right amount of hyperopic shift to negate
preexisting myopia, not to mention that astigmatism cannot be corrected this
way.

The more important and irreversible side effects include elevated intraocular
pressure leading to glaucoma risks, and poor blood perfusion to the optic
nerve leading to non-arteritic anterior ischemic optic neuritis (as mentioned
in the article inflamed optic nerve), both result in permanent loss in parts
of the visual field. The choroidal folds are unlikely to cause any change in
vision though.

So all factors considered, it's really not a great way to correct myopia.

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meowface
Could overhydration cause similar eye issues, since it also increases
intracranial pressure?

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datenwolf
Damn, as a guy in OCT research, working with the ATM most advanced OCT imaging
systems there are (which we develop ourself) it's been itching me to get one
of our systems up there for research. There's currently a Heidelberg OCT on
board the ISS, but this thing can do only 2D scans in high resolution. And
with our stuff we can do 3D scans in high resolution and even markerless
angiography.

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ISL
Though this comment comes days late -- if the effect cannot be countered,
perhaps sending farsighted astronauts to Mars would allow them to arrive with
fully-corrected vision.

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Symmetry
Gosh, if only we'd been willing to pay for research to tell us if this effect
arises in the low gravity of Mars or the Moon as well as in microgravity.

[https://en.wikipedia.org/wiki/Centrifuge_Accommodations_Modu...](https://en.wikipedia.org/wiki/Centrifuge_Accommodations_Module)

