As well as having an increased risk for presbyopia, astronauts who go into orbit around Earth have an increased risk for developing cortical cataracts. This is because they are exposed to higher doses of radiation than people who stay Earth-bound.

They also have different patterns of exposure to naturally occurring radiation. As they get further away from the protection of Earth’s atmosphere there is higher exposure to galactic cosmic rays and solar radiation.

Astronauts have a higher risk of developing cataracts than commercial airline pilots, according to Eleanor Blakely, Ph.D., a biophysicist at the Lawrence Berkeley National Laboratory. She notes that the longer astronauts are in space, and the further away they are from the atmosphere, the greater the risk.

Interestingly, according to the 2006 NASA Study of Cataract in Astronauts (NASCA), the risk is mostly for cortical cataract, but not so much for nuclear or subcapsular cataracts. That same study also found greater intake of vitamin-A was linked to a decreased risk.

So, what should space-bound astronauts do? “They are encouraged to include natural antioxidants in their diet, such as blueberries, as well as vitamins,” Dr. Blakely said.

Robert Gibson, OD, who works with astronauts at NASA’s Flight Medicine Optometry Clinic, notes that the suits astronauts wear when they go out to do space walks have filters in the faceplates to block harmful UV radiation.

“We also prescribe special sunglasses that are custom made for space flight to block UV and Blue Light. Astronauts often wear these while looking out the ISS windows at the Earth,” Dr. Gibson said. For astronauts, the potential risks of looking out those windows is worth the cost.