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The Eye of the Beholder Gwenyth Browning Jones Santagate © 1998 Humans see with two eyes. Those two eyes are placed on the front of the face. Humans focus with both eyes on the same subject at the same time. Humans can see clearly, with good light, within close distance. Human eyeballs are round. Humans are predators. Horses see with two eyes. Those two eyes are placed on either side of the face. Horses focus on two separate subjects at the same time. One view on the right side with the right eye. One view on the left side with the left eye. Horses can see clearly at far distances and they can see well without light. Horses' eyeballs are oval. Horses are prey. Out of all the domestic species of animals, horses have the lowest concentration of nerve cells which relay information from within a centrally located field. In most other animals, the optical nerve cells are concentrated within the visual streak. Horses' optical nerves extend downward towards the nose and temporally to the sides. Within the temporal arm lies a field of optic nerve cells which is denser and provides greater acuity. This offers the horse the abilities of "binocular" vision ... that of having the ability to focus on one thing with both eyes at the same time just as human eyes are capable. Each eye has a full optical vision of about 215 degrees. The panoramic view allows the horse to see just about everything around him with just slight movement of the head. The "blind spots" of the horse are directly in front of his nose and directly in back of his body unless he turns his head and neck. The horse's "monocular" vision allows the horse to view two separate views at the same time; each view with each separate eye. Horses' eyes do not adjust readily to light changes. The pupil in the eye is rectangular shaped in a horizontal position. This pupil cannot constrict well, even when a light is shone directly into the eye. The eyeball, itself, contains black orbs on iris called Corpora nigra or granula iridica. It is believed that these black nodules help to decrease the amount of light which enters the eye. It is not believed that horse can distinguish colors but has yet to be founded and proven. Located in the inner corner of each eye is a "third eyelid" called the "nictitating membrane". This third eyelid is what moves across the eye, cleaning off the cornea. Each of the two eyes have two glands located above the eyes; the superior and the inferior lacrimal glands. These glands serve to lubricate the eye. The fluid is then drained through ducts leading from the eye to the inside of the nostril forming the lacrimal ducts. Many times these ducts which drain the fluid, become plugged with dirt or mucous thus causing the eyes to "weep". A veterinarian may flush the duct to open it up and allow the fluid to drain. How does this affect the BEHAVIOR of the horse? Being an "animal of prey", the horse is the hunted one. Never the hunter. Because of this, the horse's eye serves him well. Horses which have small eyes set more on the front of the face, rather than large and on the sides are more apt to be considered mean and stubborn. The "pig eyed" horse cannot see as well as the horse with large eyes well placed on the sides of head, therefore is more apt to flee from what he may perceive as danger. The horse with nice, large eyes placed well on the sides of his head has a better panoramic view of his surroundings than the pig-eyed horse. Therefore, he isn't as jumpy and irritable, always expecting danger, as the pig eyed horse. The horse's first instinct when feeling threatened is to run for his very life. In the wild, this is the only way to survive. If the horse hesitates, the few seconds hesitation may cause him to become a meal for a predator. The pig eyed horse, with its limited fields of vision, is much more likely to misconceive danger. If the horse has nowhere to run, the fight instinct kicks in. The horse will kick out and aggressively turn to attack that which he perceives as danger. Humans, not understanding this, may well conclude that this kicking, aggressive animal is dangerous rather than trying to conform into the horse's realm of reality. When working around horses, one must keep in mind the natural instincts of the horse with relation to his physical formation. One does not walk up behind a horse without letting the horse know he's there. The horse cannot see behind him; the horse perceives the approaching human as predator; thus may flee or kick. It is difficult to approach the horse from the front without having the horse know one is approaching. However, a hand raised quickly in close proximity to the horse's face, may well take the horse by surprise and cause him to spook or shy. Horses also perceive body languages of an approaching animal or human with careful consideration. A human who approaches with an aggressive manner may well cause the horse to reject the person's subsequent, friendly advances. The horse perceives a person approaching aggressively as a predator. If the human casually approaches a strange horse with a quiet and friendly demeanor, he is much more inclined to be readily accepted with an attitude of curiosity from the horse; the horse will not perceive the human to be an approaching predator. There is much to discover about the horse, it's behavior, its physiology, it's social habits and is interesting to note the correlation between the subjects. It is obvious that the horse cannot climb a ladder since it does not have fingers or prehensile tails. But to learn about why the horse reacts to certain situations because of its physical optical makeup or its olefactory senses design can only help to deepen the relationship and understanding between the human and horse. |
