Everything about the Tapetum Lucidum totally explained
The
tapetum lucidum (
Latin: "bright tapestry") is a
reflecting layer immediately behind, and sometimes within, the
retina of the
eye of many
vertebrates that serves to reflect
light back to the retina, increasing the quantity of light caught by the photoreceptors. This improves vision in low light conditions, but can cause the perceived image to be blurry from the interference of the reflected light. It is therefore primarily found in
nocturnal animals with especially good
night vision, such as
cats,
bottlenose dolphins,
dogs, and
deer.
The reflective effect of the tapetum lucidum is often called eyeshine.
The tapetum lucidum isn't present in the human eye, which is why humans have poor night vision. The
red-eye effect in humans is due to the light from the camera flash reflecting off the back of the eye in an instant (through the blood-rich
choroid and off the
retina, not a tapetum lucidum layer). In animals
flash photographs, the eyes frequently appear to be glowing in one of a wide variety of
colors including
blue,
green,
yellow and
pink.
The tapetum works roughly on the
interference principles of
thin-film optics, as seen in other reflective tissues such as
butterfly wings, for example, of the genus
Morpho. However, different species have different types of structured tissue that lead to different mechanisms of reflective interference. Known tapetum structures include:
A type of cancer called
retinoblastoma can mimic the effect in humans.
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