Eye Problems From Space Affect At Least 21 NASA Astronauts

SternisheFan sends this report from Universe Today: How does microgravity affect your health? One of the chief concerns of NASA astronauts these days is changes to eyesight. Some people come back from long-duration stays in space with what appears to be permanent changes, such as requiring glasses when previously they did not. And the numbers are interesting. A few months after NASA [said] 20% of astronauts may face this problem, a new study points out that 21 U.S. astronauts that have flown on the International Space Station for long flights (which tend to be five to six months) face visual problems. These include "hyperopic shift, scotoma and choroidal folds to cotton wool spots, optic nerve sheath distension, globe flattening and edema of the optic nerve," states the University of Houston, which is collaborating with NASA on a long-term study of astronauts while they're in orbit.

Comments

space affect?

[Anonymous Coward]

like they exhibit a spacey behavior or demeanor?

Not enough

[Intrepid imaginaut]

Not enough hot green alien ladies to make first contact with yet, I surmise is the root cause of this problem.

Re:What can be done about this?

[Spy Handler]

aside from artificial gravity, nothing. No amount of exercise bike pedaling will save your optic nerves from being in zero G too long.

There isn't really any good reason to put people in orbit for 6 months+. Rotate them out every couple of months. Yes we needed data on long-term microgravity effects on the human body. We have them now, zero G does bad things to your body. So don't do it for extended periods.

Fly in the ointment is the expected trip to Mars, which will take 9 months to a year. Fortunately people like Zubrin have developed advanced technologies to deal with this. It's called a rope. Attach the Mars spacecraft to a ballast via a rope (they call it tether) and spin it until you get 1/3rd G. Problem solved.

Obviously...

[Type44Q]

Obviously orbital habitats either need to be spun-up or contain living quarters located within centerfuges.

Re:What can be done about this?

[ArcadeMan]

Wouldn't that be "problem 33% solved?"

Re:yeah, i'm not interesting in going to space

[SternisheFan]

From CBCnews, Mar 13, 2012:

Astronauts have complained for decades about vision problems such as blurriness following trips into space. A recent NASA survey of 300 astronauts found correctible near and distance vision problems in 48 per cent of astronauts who had been on extended missions and 23 per cent of those who had been on brief missions. In some cases, they lasted for years after the astronauts returned to Earth.

Fluid shifting toward head causes problems

In the new study, the astronauts had spent an average of 108 days in space. Their eye abnormalities were similar to those seen in patients on Earth with idiopathic intracranial hypertension. Patients with the condition have increased pressure around their brains for no apparent reason.

Among the astronauts in the study:

33 per cent had expansion of the space filled with cerebral spinal fluid that surrounds the optic nerve, which connects the eye to the brain.

22 per cent had flattening of the rear of the eyeball.

15 per cent had bulging of the optic nerve.

11 per cent had changes in the pituitary gland and its connection to the brain.

An earlier NASA-sponsored study of seven astronauts, published last November in the journal Ophthalmology, found similar abnormalities and also noted that they were similar to those experienced by patients on Earth suffering from pressure in the head. But it noted that astronauts did not experience symptoms usually associated with that problem on Earth, such as chronic headache, double vision or ringing in the ears.

The earlier study suggested that the problems might be caused by fluid shifting toward the head during extended periods of time in microgravity. This could result in abnormal flow of spinal fluid around the optic nerve, changes in blood flow in the vessels at the back of the eye, or chronic low pressure within the eye, the researchers said.

http://www.cbc.ca/news/technol...

Zero-G is bad long term, but what about 1/6-G?

[deathcloset]

This is an unintuitive wild speculation, but I wonder if these effects are a linear function of the gravity or if there is a more complex interaction.
In other words, if Alice spent 6 monts in zero-G and Bob spent 6 months in 0.166-G, and assuming equal eye health, would Bob have less damage than Alice or more?

Obviously the human body emerged out of a 1-G environment, so the eye has evolved with those pressures. But just because removing those pressures completely may result in harm, that is not to say that removing those pressures partially would be harmful.

The only non-zero-G astronauts I know of were the Apollo folks - but I can't find any information (or anectdotes from them) on the difference in physiological effects of zero-g versus 1/6th-G.

It seems like they would have experienced less intercranial pressure and would have had an actual reference for up and down.

Oh space be a harsh mistress.

Re:Zero-G is bad long term, but what about 1/6-G?

[bthecohen]

You hit the nail on the head: this is perhaps the most fundamental unanswered question in life support for space exploration. We simply have no idea.

Originally, the ISS was slated to have a module called the Centrifuge Accommodations Module. It was intended to help answer this question. It contained a large centrifuge that could hold 2-foot-tall animal cages and simulate anywhere from zero to 2g. It would have been one of the most essential experiments on the station, because there is really no way to collect data on varying levels of microgravity on living organisms other than putting a centrifuge in zero g. Unfortunately, the (mostly assembled) module was cancelled in 2005.

The engineering implications for interplanetary missions are profound, in that it might be vastly more expensive to build a 1g artificial gravity centrifuge than, as you said, a 1/6g one. But we currently have absolutely no way of knowing how many Gs we need. It's a very tough problem.