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Explanation of glaucoma in pets by Ron Kurtus - Succeed with Healthy Animals. Also refer to veterinarian, vet, ophthalmologist, eyes, fluid pressure, aqueous humor, drainage channel, pressure, tonometer, blindness, Ron Kurtus, School for Champions. Copyright © Restrictions
Glaucoma in Pets
by Ron Kurtus (3 November 2001)
Glaucoma is a disease of the eyes that occurs both in humans and animals. It is characterized by increased fluid pressure within the eye. Glaucoma can result in rapid vision loss because of the damage that high pressure inflicts on the retina and optic nerve. Although veterinaries can often detect glaucoma, detection and treatment it is usually the best at an animal ophthalmologist.
Questions you may have include:
- What causes glaucoma?
- Are there different types of glaucoma?
- How is it diagnosed and treated?
This lesson will answer those questions. Animal Health Disclaimer
Cause of glaucoma
Glaucoma is caused when the eye's internal drainage channels become obstructed.
The eye constantly produces a fluid called aqueous humor that helps to maintain the normal round shape of the eye. This fluid circulates inside the eye, nourishing cells and removing waste products, before then leaving the eye through tiny drainage channels. Glaucoma occurs when these channels become plugged or obstructed. When this happens, the fluid pressure will increase beyond levels compatible with the health of the eye.
This increased pressure can damage the retina optic nerve, resulting in partial or complete vision loss. Unfortunately, this vision loss is permanent and cannot be restored.
Types of glaucoma
In general, there are two types of glaucoma recognized in animals: primary and secondary glaucoma.
Primary
Primary glaucoma is the most common cause of glaucoma in dogs. It is caused when the drainage channels are unusually narrow or there are fewer channels than normal. As the dog ages, the drainage channels become smaller and eventually results in abnormally increased pressure within the eye.
This type of glaucoma usually occurs in both eyes, but often one eye is affected before the second eye. Primary glaucoma is usually inherited. Commonly affected dog breeds include the Cocker Spaniel, Samoyed, Chow Chow and Basset Hound, but it has been reported in numerous other breeds.
Secondary
Secondary glaucoma is a consequence of some other eye disease. It occurs when another problem within the eye such as inflammation, tumor inside the eye, trauma, or a displaced lens blocks the drainage angle. It may develop rapidly or slowly. Secondary glaucoma is the most common cause of glaucoma in cats.
Diagnosing glaucoma
Just as you physician can test you for glaucoma, you get the best diagnosis and treatment from an ophthalmologist. The same is true for the diagnosis of glaucoma in animals. Many vets have the equipment needed to check for glaucoma, but you still get the more exact diagnosis from an animal ophthalmologist.
Measurements made
The diagnosis of glaucoma is based upon measurement of the pressure inside the eye, examination of the shape and color of the optic nerve and examination of the drainage channels or filtration angle. Using special equipment, the veterinary ophthalmologist examines the external and internal structures of your pet's eyes to detect any disorders that may be present.
The pressure inside the eye is measured with an instrument called a tonometer, similar to what is used with humans. If the pressure is elevated, or if the optic nerve looks unusual, the ophthalmologist will then examine the drainage channels to determine decide what type of glaucoma is present.
Treatment
Depending on the type of glaucoma that is present, treatment may include eye drops or tablets to reduce the fluid pressure, surgery, or a combination of both. In a case of severe or chronic glaucoma where blindness is already present there are other treatments.
Summary
Glaucoma is caused when the eye's internal drainage channels become obstructed. Primary glaucoma is when the drainage channels are unusually narrow, Secondary glaucoma is a consequence of another eye disease. The diagnosis of glaucoma is based upon measurement of the pressure inside the eye and examination of the eye. Treatment can be medication or surgery.
Also see Treatment of Glaucoma in Pets
Appreciate your own vision, as well as your pet's
Resources and references
The following resources provide information on this subject:
Websites
Navigation for a Blind Dog - Helping blind dog navigate house
Lecture Notes: Update on Veterinary Ophthalmology - Excellent overview of Glaucoma from the Virginia-Maryland Regional College of Veterinary Medicine
Books
Top-rated
books on Animal Glaucoma
Top-rated
books on Animal Health
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Glaucoma in Pets