Definition: Eyeshine; Eyeshine Effect

Eyeshine; Eyeshine Effect

Photographers sometimes find strange silvery or yellow glowing eyes in images of their pets, especially when they used flash. The ‘eyeshine’ effect is where some animals and fishes show glowing eyes in low-light photos. The effect is found mainly in night hunting animals (nocturnal carnivores). They have a special layer of tissue (Tapetum lucidum) in the back of the eye that reflects visible light around inside the eye. This back-reflection intensifies the light in the eye making it easier for the animal to see its prey in very low-light conditions. Animals may have more blurry vision under these conditions but will have superior eyesight to those without the tissue.

The colour reflected back varies widely according to the species of animal. The colour can be a silvery yellow, reddish, silver, green, blue or even orange.

The eyeshine effect is rare in humans who exhibit the red-eye effect instead. When detected in humans it is usually attributed to eye diseases of various kinds. They eyeshine effect is sometimes used as a diagnostic indicator by ophthalmic consultants.

The cause of the eyeshine effect is the same as the ‘red-eye‘ effect. However, the eyeshine effect is caused by a different membrane to the red-eye effect.

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