NASA have been carrying out studies on the effects of radiation, low gravity and oxidative damage on mice that have been living on the International Space Station. Cell behavior and eye related gene expression were particularly looked at in relation to space travel. It was found that even during short space flights of up to fourteen days there were notable changes in the expression of genes that assist our cells to cope with oxidative stress in the retina, which is possibly caused by exposure to radiation.
It has been known for the past twelve years that astronauts are at increased risk of developing conditions such as premature age-related macular degeneration as sun radiation can be responsible for chemical reactions in cells, collectively called oxidative stress. Down here on Earth and protected by our atmosphere we are at far lower risk than the astronauts where in outer space there is no such protection provided.
The research noted that were some effects that were partially reversible upon return to Earth however some optic nerve changes consistent with mechanical injury did not eventually improve.
Further study will be needed to research the cellular behavior and gene expressions in apoptotic pathways ( those which help the body destroy cells that are damaged beyond repair).