Give the eye points of reference. This line of speculation leads to amazing concepts. There is another downside to the performance of human visual systems in space. This phemonemon only underscores the importance of being aware of our visual ability. As if that weren't enough, studies done by the Russians on cosmonauts on effects of perception of colors in space suggests a reduction in the perception of brightness of all colors.
Greatest degradation seems to occur in purple, azure, and green.
Visual perception of color is impaired in the space environment, with implications for color coded reference systems. And, finally, there are the light flashes. Appearing in both eyes simultaneously or one eye at a time. It is of interest that the very same astronaut who reported them in the Apollo flights failed to see them in previous Gemini flights. After the Apollo flights this phenomena was noted by the crew of all three Skylab missions especially when they crossed the South Atlantic Anomaly.