Long ago, it was believed that the light bursts and trails observed by [Apollo] astronauts were caused by high-energy, heavy cosmic particles (HZE) traveling through the eyes…. A new report concludes that the particles do not pose a significant threat to brief moon missions or Earth-orbiting missions like Skylab.
Update
Unknown is the mechanism behind the lights described by Apollo astronauts. As the particles, which are components of cosmic rays, transit through a portion of the eye, they may emit radiation.
Or they may manipulate nerve cells to create the illusion of light. However the flares occur, they continue to be a problem for astronauts.
In 2006, approximately 80 percent of NASA and ESA astronauts reported experiencing lights. Uncertain is how the phenomenon affects astronaut health after months or years in deep space.
As NASA contemplates crewed missions to Mars and the moon, scientists are developing portable magnetic shields that can deflect cosmic rays to protect astronauts from radiation (SN: 7/4/20 & 7/18/20, p. 18).