A cat’s eyes are not only beautiful but also crucial to their inquisitive nature. When you notice changes like cloudiness or redness, it can be concerning. Two conditions that can affect your cat’s eyes are uveitis and cataracts. While distinct, they are often linked.
What is Uveitis?
Uveitis is the inflammation of the uvea, the middle layer of the eye which includes the iris (the colored part), the ciliary body, and the choroid. This inflammation can be painful and, if left untreated, may lead to serious complications, including vision loss.
Signs of Uveitis:
- Redness of the white part of the eye.
- Squinting or keeping the eye closed.
- Cloudiness or a hazy appearance to the eye.
- Excessive tearing or discharge.
- Sensitivity to bright light.
- Changes in the color or shape of the pupil or iris.
- Pawing at the affected eye.
Causes of Uveitis
The causes of uveitis are numerous and can sometimes be difficult to pinpoint. They range from issues within the eye itself to systemic diseases affecting the whole body.
- Infections: Viral infections like Feline Leukemia Virus (FeLV), Feline Immunodeficiency Virus (FIV), and Feline Infectious Peritonitis (FIP) are common culprits. Bacterial, fungal, and parasitic infections can also be a cause.
- Trauma: An injury to the eye, such as a scratch from a cat fight, can trigger inflammation.
- Systemic Diseases: Conditions like high blood pressure or diabetes can lead to uveitis.
- Cataracts: The leakage of proteins from a cataract can cause inflammation.
- Cancer: Tumors within the eye can cause uveitis.
What are Cataracts?
A cataract is a clouding of the lens of the eye, which is normally clear. The lens works to focus light onto the retina, allowing for sharp vision. When a cataract forms, it blocks or scatters this light, leading to blurry vision and, in severe cases, blindness.
Signs of Cataracts:
- A cloudy, hazy, or white appearance to the pupil.
- Changes in behavior, such as bumping into furniture or being less active.
- Difficulty navigating in dim light.
It’s important to note that a normal aging change called lenticular sclerosis can also cause a cloudy appearance to the eyes, but it doesn’t significantly impact vision in the way cataracts do. Only a veterinarian can distinguish between the two.
Causes of Cataracts:
While some cats may be genetically predisposed to cataracts, the most common cause in felines is secondary to another issue.
- Uveitis: Chronic inflammation is the leading cause of cataracts in cats.
- Trauma: Injury to the eye can damage the lens and lead to a cataract.
- Metabolic Diseases: Conditions like diabetes, though a less common cause in cats than in dogs, can contribute.
- Nutritional Deficiencies: Poor nutrition, especially in kittens, can be a factor.
The Connection: Uveitis, Cataracts & Synechiae
Uveitis and cataracts are closely linked. Chronic uveitis is the most frequent cause of cataracts in cats. The inflammation from uveitis disrupts the delicate environment of the eye, leading to changes in the lens proteins that cause them to become cloudy.
Conversely, a developing or mature cataract can leak proteins into the eye, triggering an inflammatory response known as lens-induced uveitis.
A significant complication of uveitis is the formation of synechiae. Synechiae are adhesions, or scar tissue, that form between the iris and other parts of the eye.
- Posterior synechiae occur when the iris sticks to the lens. This is a common finding with chronic uveitis.
These adhesions can cause an irregularly shaped pupil and, more seriously, can block the normal flow of fluid within the eye. This blockage can lead to a dangerous increase in eye pressure, a condition called secondary glaucoma, which is painful and can cause irreversible blindness.
Diagnosis & Treatment
If you notice any signs of eye problems in your cat, a prompt veterinary examination is crucial.
Diagnosis:
Your veterinarian will perform a thorough ophthalmic exam, which may include measuring the pressure inside the eye and using special stains to check for scratches. Blood tests and other diagnostics may be recommended to search for an underlying systemic cause of uveitis.
Treatment:
Treatment is aimed at controlling the inflammation, managing pain, and addressing the underlying cause.
- Anti-inflammatory medications, usually in the form of steroid or non-steroidal eye drops, are the cornerstone of uveitis treatment.
- Pain relief is essential.
- Pupil-dilating drops (like atropine) are often used to relieve pain from muscle spasms and to prevent the formation of synechiae.
- Treating the underlying cause, such as a systemic infection, is critical for resolving the uveitis.
For cataracts, the only definitive treatment is surgical removal by a veterinary ophthalmologist. However, not all cats are candidates for surgery, especially if there is significant ongoing inflammation. In cases where surgery isn’t an option, managing the associated uveitis with medication is key to keeping the cat comfortable.
Early diagnosis and aggressive treatment of uveitis are vital to preserve your cat’s vision and comfort, and to prevent serious complications like glaucoma and cataracts.