Glaucoma is a collection of disorders that damage the retina and optic nerve, leading to vision loss.
• Glaucoma usually results from a failure of the fluid in the front part of the eye (aqueous humor) to drain as it should
• The pressure inside the eye increases as a result of fluid buildup, damaging the optic nerve and retina
• Glaucoma can present in two forms: Primary glaucoma occurs without any underlying condition and usually has a hereditary component; Secondary glaucoma results from another underlying condition, like inflammation or a tumor, and is the most common form in cats
• Glaucoma is diagnosed by using a specialized tool called a tonometer to measure pressure inside the eye
• Glaucoma is a chronic disease that nearly always leads to blindness
• Treatment focuses on alleviating pain
• Medications may help, but surgical removal of the eye is necessary if the pain becomes unmanageable
The early signs of glaucoma are difficult to detect in cats. Minor behavioral changes like lethargy, withdrawal, and hiding may appear, but normally the development of glaucoma is so subtle that these symptoms are not obvious. By the time these changes become noticeable, the cat’s vision might already be impaired.
Glaucoma is not a life-threatening condition, but it requires urgent veterinary attention because it is painful and might lead to permanent loss of sight. Glaucoma is rarer in cats than it is in dogs. Affected cats usually suffer from secondary glaucoma. Primary glaucoma is uncommon in cats even though some breeds are more predisposed than others
Primary glaucoma is relatively rare, it affects both eyes, and has a genetic and breed-related component. Secondary glaucoma is usually a consequence of uveitis, a chronic inflammation of the eye that affects the drainage ducts and can affect one or both eyes.
Uveitis is associated with various conditions including feline immunodeficiency virus, feline leukemia virus, and toxoplasmosis.
The main signs of glaucoma are:
• Cloudiness in one or both eyes • Squinting (blepharospasm) • Excessive rubbing of the eyes
• Bloodshot eye • Dilated pupils not responding to light • Eye discharge • Eyeball swelling (buphthalmos)
A tonometer is used to measure intraocular pressure and make a diagnosis of glaucoma.
Other specific tests to guide treatment include:
• Gonioscopy, to determine the damage in the draining ducts
• Electroretinography to evaluate the level of vision loss
• X-ray or ultrasound scanning to check for other optical malfunctions
Glaucoma is irreversible and progressive. Typical treatment focuses on alleviating pain and reducing symptoms. Medications to manage symptoms include
• Dorzolamide and timolol eye drops reduce the intraocular pressure
• Steroids treat the inflammation that might have caused the disease
• Pain medications
Surgical procedures may also be necessary, such as:
• Surgical removal of the eye • Fluid drainage
• Cyclocryotherapy alters the cells that produce the aqueous humor in the eyes
Glaucoma is incurable. Treatment can be useful to decrease associated inflammation. Progressive blindness is likely, but with appropriate treatment can be delayed. If the associated pain cannot be alleviated, surgical removal of one or both eyes is often the best solution.
Cats rely on their sense of smell more than vision. Owners must consider that and avoid anthropomorphization when it comes to making decisions about treatment options. Cats might take a while in adjusting to their new condition but will eventually recover and live a normal life. A caring household helps in making the process smoother for the cat. Blind cats can have a normal lifespan with a high quality of life with sufficient support and management.
There are many possible causes of glaucoma. General preventive strategies to optimize health are the only real strategies to avoid glaucoma. There is some breed disposition towards primary glaucoma so breed avoidance can prevent this specific subtype, but the condition can develop in any cat. Staying up to date with vaccinations and routine health screenings will help maintain overall health and detect issues early.
Glaucoma is not a condition common in cats with just about 0.2% of cats affected. Secondary glaucoma is the most common form in cats. It usually appears in middle-aged to elderly cats. Primary glaucoma is uncommon in cats. Siamese and Burmese cats are predisposed.
• Pain medications • Steroids • Eye removal • Fluid drainage • Eye drops to relieve pressure
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