Eyes are very important sensory organs to a cat. Being sure that your cat’s eyes are healthy should be a part of an annual comprehensive physical examination by your veterinarian. I have diagnosed different diseases of the eyes and even blindness when cats have been brought in for routine visits, because owners often don’t realize a problem exists.
An examination of the eyes starts with inspection of the eyelids and skin around the eyes. Any discharge, inflammation, or hair loss should be noted. Next the surface of the cornea is examined for any cloudiness, redness, or imperfections. If the cornea seems dry, or if a lack of tear production is suspected, a Shirmer tear test can be performed. This test uses a small piece of filter paper that absorbs tear fluid over a 60-second period of time. Normal cats will produce more than 15 mm of tears in each eye during this time.
The cornea then can be checked for surface irregularities such as a scratch or ulcer. This is performed by placing a drop of a fluorescent dye on the corneal surface, then rinsing it off. The normal cornea is smooth, and the dye rinses off. Any irregularities will trap the dye on the cornea and this can be seen with a black light or sometimes even with room light.
If cat is squinting, another procedure that should be performed is examination of the inside of the eyelids. Most cats do not allow a veterinarian to probe under the lids unless a topical anesthetic is first applied. Sometimes sedation or anesthesia is needed. A special round-ended probe is used to check under the lids. Foreign objects such as foxtails or litter can be found this way.
If the eye is bulging or if glaucoma is suspected, measurement of eye pressure can be taken with an instrument called a tonometer. Glaucoma is found in cats, but it is not as common as in humans or dogs.
There are veterinarians who are board certified in ophthalmology. These doctors will be able to perform even more specialized tests of the eye using different types of lenses and lights.
Veterinary ophthalmologists perform all types of high-tech eye surgery including replacing lenses, grafting corneas, and placing prosthetic eyes in animals that have lost an eye.
Written by Dr. Wexler-Mitchell of The Cat Care Clinic in Orange, CA
Copyright © 2011 The Cat Care Clinic