Red eye is produced when the flash is near the camera, as it is most often.
The light from the flash bounces off of the retina in the back of the subject's eyes, back to the camera, creating red eye.
Increase the ambient light by turning on all of the available light sources.
This will make the subject's pupils smaller, thereby making the red-eye dots smaller.
Avoid photographing the subject with a mug-shot-type pose.
Use a flash that mounts on top of the camera, and bounce the flash off the ceiling.
Use a separate flash with an extension cord so the flash can be held away from the camera.
Many programs that download photographs from memory cards to your computer retouch red eye.
You can also retouch photographs individually, with editing programs such as Photoshop Elements.
Go to Red Eye Be Gone!.
Why do the eyes of cats and dogs reflect back yellow or green, and not red?
They, and many other animals that are active at night, have a membrane in front of the retina called the tapetum lucidum.
Light hits the retina, and some of the light is reflected back out to the tapetum.
This reflected light is then reflected back to the retina, improving night vision.
When photographed, the light from the flash is reflected off and colored by the tapetum, not the animal's retina.