NEWS
Coming into Focus: How Do Horses See?
Horses’ Vision: How Do They See?
We want horses to carry people safely and execute jobs like traversing jumps, so vision is especially crucial.
A Anyone who spends enough time with an animal will ultimately begin to question how that species sees the world. Speculation abounds – Color is invisible to animals! Cats have night vision! — but most people are unaware of animal vision. We want horses to carry people safely and execute jobs like traversing jumps, so vision is especially crucial.
The position of the eyes in the head, for example, can have a substantial impact on vision. Consider the difference between a horse’s long, narrow head and a cat’s somewhat flatter face. Both of a cat’s eyes can easily be seen at the same time. Only from exactly in front of a horse can both eyes be seen. A grazing horse’s field of view spans nearly 360 degrees because to this adaption. Horses’ binocular vision is limited since there is only a short area where the visual fields of the two eyes overlap. Horses, however, appear to have good depth perception.
The retina, a layer of cells that lines the back of the eye, functions as a lens, focusing light on it. The retina converts light into an electrical signal that the brain can understand. The focusing mechanism of the human eye is frequently defective, necessitating the use of spectacles or contact lenses. Horses rarely have problems with their eyes’ ability to focus light, therefore you won’t see many of them wearing glasses.
The retina is the most important factor in vision. Horses have a lot of cells in their retinas and have good vision compared to other animals. “20/20” vision is a term used to describe people who have flawless eyesight. Horses are supposed to have 20/30 to 20/60 vision, which means they can see from 20 feet away what an ordinary human can see from 30 to 60 feet away (cats, on the other hand, are thought to have 20/100 eyesight). Cones, or color-sensing cells, are also found in the retina. Red, yellow-green, and blue light are detected by three types of cones in humans. Horses only have two types of cones, none of which are red. They see color, but it’s in a different hue than we do.
Cataracts and uveitis, which block or blur light entering the eye, can cause vision issues in horses. Cysts can form in the corpora nigra (the ruffled structure at the top of the pupil) and float into the visual field, causing spooking. Many of these problems can be resolved. Changes in behavior (spooking, shying, unwillingness to enter a stall or arena) or performance are signs of eyesight impairment (balking at jumps, refusal to move in a particular direction). However, such alterations can also be caused by orthopedic, neurologic, or behavioral disorders. If you notice changes in your horse, get him or her assessed as soon as possible by your regular veterinarian, who can determine whether a referral to a boarded veterinary ophthalmologist is necessary.
Stephanie Pumphrey, Ph.D.
Dr. Stephanie Pumphrey, a veterinary ophthalmologist, treats a variety of animals at Cummings Veterinary Medicinal Center with medical and surgical eye therapy. Cataracts, glaucoma, corneal ulcers, eyelid and eyelash problems like as entropion or distichiasis, and uveitis and other inflammatory illnesses are among the most commonly treated conditions.
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