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Channel Islands Veterinary Hospital


Tonometry is the measurement of pressure inside the eye and is performed with an instrument called a tonometer.

Elevated pressures in the eye can result in glaucoma, which is an increasingly diagnosed eye disease in dogs and cats. It often results in irreversible blindness and is usually painful for the animal in its more advanced stage.

Primary glaucoma can occur spontaneously in certain breeds of dogs and most commonly afflicts dogs at 3-7 years of age but can occur at any age. The disease is most frequently seen in Cocker Spaniels, Poodles, Beagles, Chow-Chows, Bassett Hounds, Dalmatians and many of the terrier breeds; however, it has been identified in almost every breed of dog.Primary glaucoma often occurs in one eye initially but can develop in the other eye within weeks to months. Dogs with early glaucoma may only have a mild redness to the eye. As it progresses, it can cause a bluish-white discoloration of the cornea. It is important to understand that high elevation in the intraocular pressure can cause irreversible damage to the retina and optic nerve in a very short period of time (24-48 hours), resulting in blindness in the affected eye. As a result, glaucoma is considered an emergency and requires immediate treatment if vision is to be maintained. Glaucoma that is severe and lasts more than 10-14 days often causes an enlargement of the eye.

Secondary glaucoma may be caused by cataracts, lens displacement, inflammation, trauma or certain forms of cancer of the eye.

Contact us right away if you notice any of the following signs in either or both of your pet’s eyes: dilated (enlarged) pupils, clouding of the cornea (the normally clear outer layer of the eye), red or bloodshot eyes, squinting, tearing or one eye protruding or appearing larger than the other. Because glaucoma is painful, your pet may react by rubbing or pawing at the eyes or rubbing his or her head against the floor or furniture more than normal.