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Whoever said that getting old isn't for sissies knew what they were talking about. All of us, including our dogs and cats, find that as we age our bodies just don't work as well as they used to. Eye diseases are among the most common problems in older dogs and cats.

One change you may notice is a condition called lenticular sclerosis, or nuclear sclerosis. That bluish haze you may see in a pet's eyes isn't cataracts, as is often suspected, but the result of a normal aging of the lens. The good news is that it doesn't affect vision and doesn't require any treatment.

Cataracts are cloudy spots on the normally transparent lens of the eye. They look like a milky gray film behind the pupil. Cataracts may start to appear when dogs are 6 to 8 years old and can eventually lead to blindness. Dogs rely more on scent than sight, however, and they can get around very well simply by using their noses — as long as you don't move the furniture. If your dog's cataracts are so bad that it's running into things, ask your veterinarian about cataract surgery.

Older cats rarely develop cataracts. They are more likely to suffer vision loss from retinal diseases, uveitis (a painful inflammation of certain eye structures) or glaucoma. Like dogs, cats adapt well to vision loss. They compensate by relying more on their hearing or their whiskers.

Other age-related vision problems, such as keratoconjunctivitis sicca, better known as dry eye, require aggressive treatment. Tears, which are produced by the lacrimal glands, lubricate, protect and cleanse the eye.

Tear production tends to decrease with age. If that happens, the eye becomes dry and irritated. It starts to produce more mucus, causing a goopy discharge. Dry eyes are itchy, and dogs may scratch at them or rub them on the carpet in an attempt to relieve the itch. Dogs with dry eye are also more likely to develop corneal ulcers.

Dry eye can be diagnosed with a Schirmer tear test. The veterinarian places a tiny paper strip at the inner corner of the eye, where the tears pool, and holds it there for one minute to see how much of the strip becomes wetted with tears. If the result indicates that tear production is below normal, the animal likely has dry eye. Dry eye is less common in cats than in dogs.

Depending on the condition of the eye, your veterinarian may prescribe artificial tears (not saline solution), antibiotic eyedrops or an immunosuppressant drug that stimulates tear production. This helps to keep the dog comfortable and the cornea healthy. The medication may need to be compounded at a special pharmacy.

Glaucoma is an increase in pressure within the eye. It can develop quickly and is extremely painful. If your pet is squinting and the eye is tearing and feels harder than normal, consider it an emergency. A dog or cat with an acute case of glaucoma can lose its eyesight within 48 hours if the condition isn't treated immediately.

Take your dog to the veterinarian for an eye exam anytime you notice the following signs: redness, cloudiness, discharge, opaque or whitish film over the eye, tearing, squinting, pawing at the eye or other signs of pain, sensitivity to light, an unusually soft or hard eye, a swollen, crusty or itchy eyelid, a bulging or sunken eye.

If you notice that your pet's vision is not as keen as it used to be, don't simply chalk it up to old age. Oftentimes, medication or other treatment can help, especially if the problem is diagnosed early.