When light passes through the retina, it captures some while the rest passes proceeds to the Tapetum Licidum (Winifred & Krause 16). The mirror like layer of cells sequentially reflects light back to the retina (Winifred & Krause 16). This ricocheting of light is what gives off the green like flash in the animal’s eye at night (Winifred & Krause 16). Reflected light in the retina facilitates concentration of light, which enhances visualization. This process gives the animal greater and higher vision besides enabling them to hunt or scavenge their prey at night.
Conversely, the “red eye” color characterizes animals that do not have Tapetum Licidum (Pendergrast 23). Therefore, this implies their eyes are not ready for the sudden entry of light except during incidences characterized by much light, which then penetrates into the eye, for instance, photographing. The “red eye” glow appears when thick light passes through the pupil of the eye and bounces off the red organs and blood capillaries in the eye.
The amount of melanin in the eye can also cause “red eye” effect. People with high melanin level in the eye tend to absorb higher light intensity. Therefore, little light reflects on the red blood capillaries and body tissues leading to the absence of the “red eye” effect.
Presently, numerous cameras have an installed feature meant to reduce “red eye” effect that works when flash goes off twice. The first flash makes eye pupils contract, hence making them smaller. The second flash, which is the actual one for taking pictures, finds the pupils smaller and reflects light on fewer blood vessels.