The Eyes of the Dog
Because dog’s have two eyes, they have binocular vision, which means that there is an area in the vision of which the two eyes overlap with each other. Binocular vision provide depth of perception which is vital to pursue prey.
The vast majority of dogs have a total visual view of 250 degrees and most dogs have their binocular vision overlapping at 75 degrees for those dogs of which have long noses and 85 degrees for those dogs of which have short noses. On the other hand humans have a total visual view of about 120 degrees, although regarding the fact that human eyes are set to be on the front of the head and not the side of a head humans have an actual total visual view of only about 190 degrees, providing the dog a 60 degree advantage in peripheral vision.
All dogs at one time were believed to be color blind, but thanks to new studies conducted by scientist it is believed that dogs can perceive a limited amount of colors. Dogs though, disregarding the fact they have greater peripheral vision, cannot perceive detail nearly as well as humans can. A non-moving object is almost hidden from a dog’s vision. Once a dog is unsure of what they are seeing they rely on their nose and sense of smell to confirm any of their doubts. Even though non-moving objects can be easily missed by a dog’s eyes, the vision of a dog is highly sensitive to objects in motion. Dogs can perceive direction, speed, and may even be able to recognize an animal or human based on their pattern of movement.
The vast majority of dogs have brown colored eyes, but there are some breeds with speckled, golden or hazel, or pale blue colored eyes. There are a few dogs that have different colors in each of their eyes. The shape and eye placement on the dog’s head varies from breed to breed. Many breeds have oval eyes that are placed midway between the side and front of their faces.
A dog’s eye functions much the same as any mammalian eye. The eyeball is round in shape with a light sensitive membrane, called the retina, lining the rear of the eyeball. Incoming light is focused and information is transmitted to the brain via the optic nerve. The dog’s eye has a reflecting layer, called the tapetum lucidum, which intensifies available light, giving the dog an advantage during dusk or dawn, the prime time for hunting.
Terms Dog Fanciers Use to Describe Certain Specifications of a Dog’s Eyes:
An eye that is clear blue but flecked with a white or lighter blue is known as a China Eye.
Dogs with a prominent, visible third eyelid (nictitating membrane) are said to have Haw Eyes. Haw eyes are seen in such breeds as the St. Bernard and Bloodhound.
Triangular eyes have a three cornered, tent shaped appearance and are seen in Afghan Hounds.
Wall eyes, characterized by a pale bluish-white iris with flecks of brown, are seen in some Harlequin Great Danes.
Prominent eyes are big, round projecting eyes such as seen on Pugs.
Other eye shapes include Almond, Circular and Oval.