Lots of things can degrade your vision. The iPhone screen I'm looking at right now is one of them. The coffee I'm drinking is another.
From waking suddenly in the middle of the night to bright midday sun to diet to age, lots of things effect eyesight. Some of them temporarily some permanently. :-(
I stopped using my phone for anything but calls and stopped ingesting caffeine for a week and my hawk eye youthful eyesight returned!
Which is why I said all BUT the bowel. Bowel shots really don't cause any damage because a shot to the bowel will cause a sympathetic response and divert blood away from that location. COD from a bowel shot is more likely going to be sepsis than hemorrhage, and that takes at least 2-3 days to form.