“The eyes are the windows to the soul” may sound like a lofty, poetic expression, but your pet’s doctor relies heavily on the examination of your pet’s eyes to determine if there is disease within the eyes, around the eyes or in the entire body.

Parallels frequently are drawn between a camera and the eye because of the similarities in structure and function. Eyelids protect the eye like a lens cap might protect a camera. The lens within the eye can focus light just as the camera’s lens. The pupil can regulate light within the eye just as our camera has adjustments for shutter speed and aperture. And the retina can record the image, just as film will in our cameras.

Failure in any part of this system can result in a pet who bumps into objects (especially when taken out of the familiar home environment), squints, rubs its face, has large amounts of discharge from its eyes or has redness or swelling to the tissue around the eyes.

Our pets have three eyelids: an upper eyelid, a lower eyelid and a third eyelid in the corner of the eye adjacent to the nose. Irritants such as dust, smoke and pollen can cause eye discomfort and redness, but so can carpet fresheners, potpourri, perfume and scented candles. This irritated tissue around the eye rapidly can become inflamed or infected and lead to conjunctivitis. While it is not a serious problem, the eye irritation can cause scratching and rubbing of the eyes, which can lead to more serious eye problems such as ulcers and abrasions of the cornea.

What are cataracts? The lens within the eye should be clear. But often the lens within the eye becomes smoky in appearance. This discolored lens is called a cataract and it may occur in young or old pets, purebreds or mongrels, in one eye or both eyes. Cataracts cause visual impairment by limiting the amount of light that reaches the retina and keeping the light from focusing onto the retina. Cataracts can be caused by trauma, diabetes or heredity. Some dog breeds are more likely to have cataracts: miniature schnauzers, Old English sheepdogs, beagles, cocker spaniels, German shepherds, Siberian huskies, Boston terriers and poodles.

Looking carefully into your four-legged child’s eyes can reveal a lot about your pet’s health. Recognizing and treating diseases that might rob our pets of their vision will not only enhance their enjoyment of life but will deepen the bond between us and them.

— Dr. Dennis Selig is a veterinarian at Northwood Hills Animal Hospital in Gulfport, Miss.