Glaucoma is a painful eye disease in dogs where there is an increase in the pressure within the eye. This increase in intraocular pressure results in compression of the nerves and blood vessels that supply the visual layer of the eyeball, called the retina. If left untreated, glaucoma will cause death of the retinal cells and blindness.
Eye Disease in Dogs: Causes of Glaucoma
To understand glaucoma, it is necessary to review the anatomy of the eye. Aqueous humor is the fluid within the front part of the eye, and is made by the ciliary body which sits behind the iris. The aqueous then flows through the pupil (hole in the center of the iris) to the front of the eye and is drained out of the anterior chamber through the iridocorneal angle. Anything that interferes with the drainage of aqueous can result in glaucoma. Glaucoma in dogs can be divided into two groups, primary and secondary. Primary glaucoma is more prevalent is purebred dogs and is related to a structural problem with aqueous outflow from the anterior chamber. Secondary glaucoma is caused by other eye diseases including uveitis (including Golden Retriever Uveitis), lens luxation, bleeding into the anterior chamber, trauma, and cancer.
Dogs with glaucoma exhibit signs of pain which can include rubbing the eyes, squinting, and blinking. Affected eyes can have red conjunctiva and sclera, and the cornea can turn blue as it is stretched and becomes edematous.
Diagnosis is made by measuring the pressure within the anterior chamber using a special instrument. A normal pressure within the eye is between 10 and 25 mm Hg, and dogs with glaucoma can have eye pressures measuring as high as 60 mm Hg.
Treatment is aimed at decreasing the intraocular pressure as soon as possible. Often the dog requires hospitalization while medication is administered. The goal is to decrease the formation of aqueous humor by the ciliary body and to increase the aqueous drainage if possible. This requires a combination of oral and topical eye medications and sometimes surgery. The long-term prognosis for primary glaucoma is poor while that of secondary glaucoma depends on resolution of the underlying cause.
If a dog loses vision in the affected eye and the pain from glaucoma cannot be controlled, surgical removal of the eye is recommended as this will provide comfort to your dog.
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