page_title: Tapetum lucidum
section_title: Eyeshine
hierarchical_section_title: Tapetum lucidum / Eyeshine
caption_attribution_description: English: Reflection of flash from the tapetum lucidum.
context_page_description: The tapetum lucidum is a layer of tissue in the eye of many vertebrates. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light available to the photoreceptors. The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep sea animals.
  Similar adaptations occur in some species of spiders. Haplorhine primates, including humans, are diurnal and lack a tapetum lucidum.
context_section_description: Eyeshine is a visible effect of the tapetum lucidum. When light shines into the eye of an animal having a tapetum lucidum, the pupil appears to glow. Eyeshine can be seen in many animals, in nature and in flash photographs. In low light, a hand-held flashlight is sufficient to produce eyeshine that is highly visible to humans (despite our inferior night vision). Eyeshine occurs in a wide variety of colors including white, blue, green, yellow, pink and red. However, since eyeshine is a type of iridescence, the color varies with the angle at which it is seen and the minerals which make up the reflective tapetum-lucidum crystals.
  White eyeshine occurs in many fish, especially walleye; blue eyeshine occurs in many mammals such as horses; green eyeshine occurs in mammals such as cats, dogs, and raccoons; and red eyeshine occurs in coyote, rodents, opossums and birds.
  Although human eyes lack a tapetum lucidum, they still exhibit a weak reflection from the fundus, as can be seen in photography with the red-eye effect and with near-infrared eyeshine. Another effect in humans and other animals that may resemble eyeshine is leukocoria, which is a white shine indicative of abnormalities such as cataracts and cancers.
caption: Reflection of camera flash from the tapetum lucidum
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