What Causes Red Eyes in Photos?

Light from a camera’s flash has all the visible light colors (red, orange, yellow, green, blue, indigo, and violet).

The pupils of your eyes are actually holes covered by a thin skin. Light can pass through this skin covering.

Light enters the eye through the pupil and hits the retina (back inner wall of the eye). Some of this light is absorbed by the eye and some of the light is scattered, meaning to be sent away from the retina in all directions.

How Light Reflections Cause Red Eye in Photography

There are many blood vessels in the eye. Red light is scattered when the incoming light strikes any of these vessels. Some of this red light exits through the pupil and enters the camera. Thus, the pupils on the photo are red.

Now that we know why eyes are red in some photos, see  RED EYE To discover how to prevent it.