According to a recent National Geographic article, astronauts returning home after longer missions suffer permanently impaired vision. This is a problem that must be addressed in hard-science worlds if realism is desired - yet it is often overlooked.
Some of the other problems associated with microgravity are easier to deal with - muscle atrophy can be reversed by exercise, bone can be replaced or strengthened over time, the immune system can heal, coordination comes back, and cancer (from radiation exposure) is treatable.
But how do you prevent vision from becoming permanently impaired?
Context of the Condition
From the article linked at the top
- Called "visual impairment intracranial pressure"
- Not fully reversible (even by surgeries) when you get back to Earth
- Occurs when cerebrospinal fluid builds up behind the eyes, which happens when gravity is reduced
- Eyeballs are literally "flattened"
- The solution scientists have proposed is "clunky" and entails being hooked into a machine to draw fluid throughout the body
Criteria for Solutions
- Artificial gravity would fix the problem but it is not and will not be present for all (if any) missions; it will not be accepted
- Will optimally be noninvasive (tubes running into the skull aren't great) but this is not a necessity
- Should be portable (being hooked into a large machine might help, but when mining asteroids or traversing the moon, there really isn't time)
- Should be science-based
- Should not involve modifying the human genome
- Should focus on preventing the syndrome as opposed to correcting it after it occurs; it's not viable to do multiple missions, then get a new prescription and/or have a new surgery after each one