I noticed this effect tonight as I was looking at the surface of a glass of hazy water with 1.7W of 445nm shining through. It's kind of a shocking thing to see at first.
http://en.wikipedia.org/wiki/Blue_fi...tic_phenomenon
There are tiny blood capillaries in your eye that, due to red blood cells, have been occluding blue light slightly since you were born. Your brain has learned to ignore them. White blood cells are less common in the blood than red cells and don't block as much blue light. When you look at an evenly lit bright blue surface, you can actually see the white blood cells swirling around! This looks different from 'seeing stars' or dehydration spots, they actually look more like single celled organisms swimming around. Freaky!