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The eyeball is round in shape with a light sensitive membrane, called the retina. The retina is a thin layer of tissue that lines the back of the eye on the inside. It is located near the optic nerve. The purpose of the retina is to receive light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition. The optic nerve function is to transfer visual information from the retina to the vision centers of the brain by using electrical impulses. The dog's eye has a reflecting pigment layer lying behind the visual receptors of the retina of certain mammals, which gives a shining appearance to the eyes when illuminated in the dark. This is known as the tapetum lucidum, and is most helpful if you intend on using your dog for hunting. Because dogs have two eyes, they have binocular vision. This gives the dog a total visual field that overlaps, providing them with depth perception needed to pursue prey. The degree of binocular vision depends on the shape of the dog's head and the exact placement of the eyes.

Most dogs have a total visual field of 250 degrees and a binocular overlap of 75 degrees for long nosed dogs to 85 degrees for short nosed breeds. We as humans have 120 degrees of binocular vision, but since our eyes sit directly on the front of our face, we have a total visual field of 190. This gives dogs the advantage of 60 degrees more peripheral vision. There are certain dog breeds that have reduced peripheral vision due to having deep setting eyes.

Dogs can not perceive detail as well as we do. They have difficulty seeing objects that not moving and rely on their sense of smell to confirm any doubts. Moving objects are rarely missed by dogs. They can perceive direction, speed, and may be able to determine an animal or human by their pattern of movement.

At one point, it was believed that dogs were color blind, but now we believe that dogs have enough color preceptor cones in their eyes to see a limited palate of colors. These cone cells are located in the retina.

Most dogs have brown eyes, but there are some breeds that have pale blue eyes, speckled, golden or hazel colored eyes. Some dogs have one eye that is blue and the other brown. The shape of the eye and the placement of their head can vary depending on the breed. Most of them are oval and placed midway between the side and front of their faces.