- Go to the site and choose “Ask Us”
- Then click on Answers to previous cosmic and heliospheric questions
- Then click on Cosmic Rays, Energetic Particles, Plasma
- Here you’ll find two questions that bear on eyesight:
Under “Light from Cosmic Rays”:
I have also read that different astronauts have claimed to have seen what they believe are cosmic rays when they closed their eyes. These were as brief bursts of light. Is this true?
The light astronauts may see when they close their eyes is caused by cosmic rays – but it’s produced via a mechanism known as Cherenkov radiation. The particles actually produce the light inside the eyeball.
Dr. Louis Barbier
Cherenkov radiation may also explain why some people see flashes during intense radiotherapy for cancer. To learn more about inside the eyeball flashes, have a look at these search results from usa.gov on [Cherenkov radiation eyes].
Under “Cosmic Ray Effects on Humans”
Cosmic rays definitely can have an effect on astronauts, including those on the space station. One well-known effect is that a higher percentage of astronauts develop cataracts than do people who have not been in space.
If you’re interested in going deeper on astronauts developing cataracts from cosmic rays, you can browse this list of search results from usa.gov on [astronaut cataracts].