COMMENTARY

View From Space: Priceless, but for Astronauts, Also Damaging

Roger F. Steinert, MD

Disclosures

March 27, 2017

Our collective fascination and appetite for space travel and exploration are insatiable. We all want to know what else is out there, making this one topic that we can all agree upon, regardless of our politics.

Hollywood has certainly benefited from our interest in space travel and extraterrestrial life over the past few years, with recent movies such as The Martian and Arrival.

What is regularly missing from space movies, however, is the physiologic impact of travel on a human being. Exactly what happens to our bodies when we come back down to Earth? And because we are ophthalmologists, after all, what happens to our eyes when we're back on terra firma?

Many astronauts experience a hyperopic shift in their visual acuity after spending several months in microgravity. On examination of these astronauts, there is posterior globe flattening and optic disc edema, which would account for this hyperopic shift. This phenomenon has been labeled visual impairment intracranial pressure (VIIP) syndrome.

There have been many hypotheses as to why VIIP syndrome occurs. Researchers have theorized that the syndrome is caused by a microgravity-induced buildup of cerebrospinal fluid (CSF) in the orbit and ventricles in the brain. At a recent meeting of the Radiological Society of North America, Noam Alperin, PhD, presented the orbit and brain MRI scans of seven long-duration astronauts, all of whom showed a significant increase in ventricular and orbital CSF volume when compared with short-duration astronauts.[1] The increase in CSF volume compresses the posterior pole of the globe and optic nerve.

Any hyperopic shift reported has been mild up to this point and can be correctable with glasses.

Travel to Mars is still a dream being carefully considered and worked towards, but we will not know what the effects of such extended space travel are until the first human being is over that wall.

There is still so much that we do not know.

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