Abnormally high pressure in the eye leads to glaucoma. Glaucoma treatment is available and ranges from medications to surgery.
What Is Glaucoma? - The eye nourishes itself and maintains its shape by producing a clear fluid called aqueous humor. In a normal eye the amount of fluid produced is always equal to the amount leaving the eye; that way the pressure within the eye (intraocular pressure) is stable. If more aqueous humor is produced then what is leaving the eye then the intraocular pressure goes up, resulting in glaucoma. This increased pressure can cause the eye to bulge and become enlarged.
Diagnosing Glaucoma - Glaucoma in dogs and cats is classified as either primary or secondary. Primary glaucoma is an inherited eye defect that affects both eyes. Breeds that seem predisposed to this eye condition include but are not limited too: Cocker Spaniel, Boston Terrier, Shar Pei, Basset Hound, Chow Chow, and Labrador Retriever.
Secondary glaucoma is the result of another eye disease obstructing the drainage of the aqueous humor. Other diseases that might cause this include uveitis (inflammation in the eye), cancer of the eye, lens luxation, and trauma that causes the eye to fill with blood. Glaucoma in cats is almost always considered secondary – usually to uveitis. Primary glaucoma or inherited glaucoma is very rare in cats.
Diagnosis is done by measuring the intraocular pressure (IOP) with a Schiotz tonometer or a Tonopen. These devices are placed on the eye and several readings are taken and then averaged. The normal IOP range is from 12 to 22 mmHg. A value greater then 30 mmHg is diagnostic for glaucoma.
Glaucoma Symptoms – Symptoms of glaucoma include but are not limited too:
- A very Painful Eye – Animals cannot speak to tell us that they are in pain so they show us by seeming irritable, not eating, hiding, and seeming lethargic.
- Reddened eye.
- Green or yellow discharge from the eye.
- Dilated pupil that doesn't react to light.
- An eye that may suddenly appear blue.
- In later stages the eye will appear large or bulge out.
Dogs and cats that show any of these symptoms should be examined immediately. Glaucoma is very painful and is an emergency. Vision can be lost quickly if treatment is postponed. Glaucoma is progressive and can eventually effect both eyes.
Glaucoma Treatment – Glaucoma is very expensive and difficult to treat. Many times the glaucoma has already advanced to a point where sight is already lost in one eye; so it becomes a race to try to save the vision in the remaining good eye. Treatment is in the form of medications and surgery.
- Medications, in the form of eye drops, are available to treat glaucoma. These eye drops will either help to decrease the production of fluid in the eye or increase drainage of fluid; either way the goal is to decrease the pressure in the eye. Medications are usually not a long term fix, most patients will eventually require surgery.
- The surgical procedures that are available are also meant to decrease the pressure in the eye. A laser cyclophotocoagulation is done by destroying part of the eye that produces the aqueaus humor. This procedure may help to save the eye if the patient can still see. If the patient is blind and the eye is painful then the eye can be surgically removed (enucleation). During an enucleation the bad eye is removed and the skin sewn shut. The fur will then grow back over where the eye used to be. Implants are also available if the client would prefer a “fake” eye. Enucleation relieves the severe pain of glaucoma and can increase the pets quality of life. Blind animals can and do live very full and happy lives.
References:
Common Diseases of Companion Animals, Alleice Summers, MS, DVM (Mosby, Inc. 2002)
Glaucoma, Animal Eye Care.LLC
Glaucoma In Cats, PetPlace.com
Glaucoma In Veterinary Patients, Eyevet.info
