Now this is quite unexpected, in today's CNN LightYears:
...Because when [Mike] Barratt blasted off to the international space station, he needed eyeglasses for distance. When he returned to Earth, his distance vision was fine, but he needed reading glasses. That was more than two years ago. And he’s not getting better. [Note: Barratt is 45 years old, presbyopia is not the issue here, the surprising aspect is the shift from myopia to emmetropia or slight hyperopia.]
“We really need to understand this. This is a critical point for understanding how humans adapt to spaceflight,” he said. [Absolutely.]
In the past few years, about half of the astronauts aboard the international space station have developed an increasing pressure inside their heads, an intracranial pressure that reshapes their optic nerve, causing a significant shift in the eyesight of male astronauts. Doctors call it papilledema. [Note: It seems the posterior pole got re-shaped (flattened) causing some changes in optic disc morphology and a decrease in the axial length. This may not be papilledma per se; let's not scare the astronauts with this stuff.]
Female space travelers have not been affected. [Note: Now this is truly amazing if true.]
Some of the astronauts slowly recover. Others have not. [Duration, please.]
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