Complete Care for Your Aging Cat - Amy Shojai [102]
An instrument such as an Schiotz tonometer or Tono-Pen measures the pressure inside the eyeball to diagnose the condition. The tonometer is gently balanced on the cornea (after drops numb the area), and a scale on the instrument indicates the pressure. The Tono-Pen is much smaller and contains a computer microchip that registers a reading when it’s merely tapped on the surface of the eye.
Treatment
“Glaucoma is an emergency. You need to have an animal evaluated by the veterinarian and treated immediately,” says Dr. Davidson. It only takes a few days for permanent damage to occur.
The condition is treated very aggressively. Eye drops usually are prescribed but don’t tend to work in cats nearly as well as they do in dogs. Beta-blockers such as timolol and metipranolol, and carbonic anhydrase inhibitors such as dorzalamide may be more helpful when combined with other therapies rather than used alone. These medicines help to relieve the pain, contract the pupil and reduce the inflammation. Some treatments help move the fluid and water inside the eye, says Dr. Gerding.
When medication doesn’t control the condition, sometimes surgery is necessary, says Dr. Davidson. Surgery is available from ophthalmologists. Ask for a referral to an eye center.
Nurse Alert!
Once glaucoma is diagnosed, the cat needs eye drops several times a day, perhaps for the rest of his life.
Should he require surgery to remove the eyeball, watching the area and keeping the socket clean with warm water on a cotton ball will guard against infection. You may also need to apply ointment until the area is fully healed.
A collar restraint may be necessary to prevent the cat from pawing at and damaging his sore eye. Cats often refuse to eat while wearing an E-collar, so remove it during meals and supervise his activity.
Options include tiny shunts implanted inside the eyeball to drain excess fluid and control the pressure. Cryosurgery may be used to freeze the fluid-producing cells. One of the most recent and successful innovations uses an ophthalmic-size laser to perform a procedure called laser ciliary body ablation. It selectively destroys fluid-producing tissues in the eye, and so reduces fluid production, says Dr. Gerding. However, the expensive equipment necessary for this procedure is limited to only a handful of veterinary ophthalmic centers in the country.
The cat’s pupil will no longer response to light when the disease has progressed to blindness. If medication can’t control the pain, then several surgical options are available. A schleral prosthesis—a silicon ball—is often placed inside the damaged eyeball after the painful internal structures have been removed. This is also a good cosmetic procedure, in which the cat keeps his eye, and the eyeball will still move, but he’ll have no vision.
Another possibility is to remove the eyeball altogether, in a procedure called enucleation. If enucleation is performed, a prosthetic implant may be placed, or sometimes the socket is left empty, and the eyelid is sewn shut.
Cats with vision loss in one or both eyes tend to adjust quickly and do very well. Removing the eye offers such great pain relief that the cat becomes even more active after the vision loss.
Bottom Line
Costs to treat glaucoma vary from $300 to $1,000 depending on the type and severity of glaucoma and the size of the cat, says Dr. Davidson.
The cost to implant the prosthetic implant generally runs about $600 per eye.
HEART DISEASE
Heart disease tends to strike young to middle-age cats. One if its forms, cardiomyopathy, is a disease that affects the muscles of the heart in various ways. The hypertrophic form is most common, and results when the muscle wall of the heart thickens. That reduces the size of the internal heart chambers until they can’t fill with enough blood. Heart failure results when the damaged muscle is no longer able to move blood throughout the body properly.
Some breeds seem predisposed to the disease. Researchers