Monday, October 28, 2013
I looked up the reason why there's such an arresting shine in cats eyes at night. It's called "eyeshine."
1. A membrane on a cat's eye, called the tapetum lucidum, is designed to reflect light within the eye itself which allows more light to reach the retina. That flash of a cat’s eyes in the dark that you see once in a while called “eyeshine,” is light reflecting off of the cat’s tapetum.
Further reading revealed why cats see so well at night.
1. Cats have elliptical pupils that are oriented vertically. This elliptical pupil allows it to open much larger than a human’s round pupil. This larger pupil lets in more light and enhances a cat’s vision in low light.
2. The cat’s retina is also designed for vision in low light conditions because it's made up of many more rods than cones. Rods are more effective than cones at absorbing light. Cones are responsible for absorbing color and yielding color vision (which is more limited in cats than humans). Much like dogs, cats see blues and violets better than reds.
So, the large pupil and reflective tapetum maximize the light that reaches the retina, which is saturated with rods that are very effective at absorbing light. All of this works together to send a signal along the retinal nerve to produce an image in the cat’s brain, even in the dark of night.
Eyeshine • 8" x 8" watercolor and gouache framed to 12" x 12" • $200