ShowBiz Feature V


food is essentially immobile and not particularly chal- lenging to identify or capture, much of the horse's vi- sual adaptations appear to be defensive and devoted to ensuring the horse’s survival by more easily identifying potential threats. Light passes through the eye and lands on the back


layer called the retina which contains rods and cones which are the cells that detect light. Rods sense light in black and white, cones sense colors. While horses have a similar ratio of cones to rods as humans (20 to 1), in horses the distribution of cones is different. In the human eye, cones are packed


together much more centrally in the retina. For horses they are much more widely distributed over the retina but also clustered near a “visual streak” which runs horizontally side to side in the retina. This streak pattern con- forms to the line as earth and sky meet, enhancing the ability to scan the hori- zon for any movement. In low light, and in the dark, most of


the vision is done by rods. As the mid- day sun floods the back of the eye, the highly sensitive rods are overwhelmed and the color sensitive cones pick up the primary role in vision. Horses have a number of adapta- tions to aid vision in both dim light and


ision is a complex pro- cess that involves not only the eye focusing and detecting light that may vary in intensity, but also the brain in- terpreting what the eye is sensing. Since the horse's


bright light. Their eyes are among the largest in do- mestic animals and they can dilate their pupil 6 times larger than humans. Their horizontal slit like pupil can dilate into a nearly round configuration at night letting in more light. At the back of the eye, behind the retina is the tapetum that reflects light. This ability to reflect the light, gives the receptors a second chance to cap- ture the light enhancing night time vision. Just shine a light at a horse at night and the reflection you see is the light bouncing off of the tapetum. People do not have this. At the same time the horse has adaptations to deal with bright light such as the slit like pupil that can be closed tight to fend off the light. On the top of the pupil you will see what looks like a small piece of tissue hanging down. This is called the


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