The Red Eye tool removes red eye in flash photos of people or animals, and white or green reflections in flash photos of animals.
Red eye is caused by a reflection of
the camera flash in the subject’s retina. You’ll see it more often
when taking pictures in a darkened room because the subject’s iris is
wide open. To avoid red eye, use the camera’s red eye reduction
feature. Or, better yet, use a separate flash unit that you can
mount on the camera farther away from the camera’s lens.