Astronauts on extended space missions have enough to worry about, what with the xenomorphs, the orbital cascades and the sentient planets. In recent years, mission control doctors have noticed another alarming trend. Astronauts who spend long periods of time in space often come back with significant vision impairment.

So what's causing this damage to the eyes? Researchers at the University of Miami appear to have figured it out. Apparently, long exposure to the zero-gravity conditions of orbital mission can cause the body to overproduce cerebrospinal fluid, which otherwise protects the brain and delivers nutrients. Too much of the stuff causes pressure on the eyeballs, slightly flattening and changing the shape of the retina. If you're taking notes at home, the condition is officially known as visual impairment intracranial pressure syndrome. Julian Huguet has the details in today's DNews report.

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Phys.org: Astronaut vision may be impaired by spinal fluid changes: study