Uveitis

Laurie Anne Walden, DVM

Photo by Wall Boat on Flickr

Uveitis is inflammation inside the eye. Some of the many conditions that cause uveitis affect the whole body, so a diagnosis of uveitis often triggers a series of tests to find the cause.
 
The uvea is a pigmented layer within the eye. The iris, which gives the eye its color, is the part of the uvea that you can see when you look at your pet’s eyes. The other structures of the uvea (ciliary body and choroid) are behind the iris, sandwiched between other layers of the eye.
 
The uvea has a blood supply to deliver nutrients to the eye, so anything that can travel through blood vessels—like infectious organisms and cancer cells—can reach the uvea and cause uveitis. The uvea also produces and drains fluid within the eye. Inflammation of the uvea interferes with fluid balance inside the eye, so untreated uveitis can lead to glaucoma (increased eye pressure) and blindness.
 
Causes
Some of the things that cause uveitis are problems with the eye itself:

• Cataract
• Trauma to the eye (like a blow to the face or a poke from a cat claw)
• Corneal ulcer
• Corneal infection
• Cancer of the eye

 
Problems outside the eye can also cause uveitis:

• Viral, bacterial, or fungal infection that spreads throughout the body
• Cancer that spreads to the eye
• Immune-mediated disease
• Diabetes and other metabolic disorders
• Adverse drug effect

 
Signs
Uveitis causes the same nonspecific signs of eye trouble (like redness) as nearly every other eye disorder. It can also cause changes that are more specific to inflammation inside the eye, like a change in iris color. Animals with uveitis sometimes have no obvious signs at all.
 
These are some of the signs of uveitis:

• Redness of the white part of the eye
• Squinting
• Iris color change
• Blood inside the eye (behind the clear cornea at the front of the eye)
• Change in pupil shape
• Difference in pupil sizes of the 2 eyes
• Cloudy appearance of the eye
• Blindness

 
Diagnosis
Uveitis is diagnosed by examining the eye with an ophthalmoscope to look for signs of inflammatory debris inside the eye. The eye exam might be the only diagnostic test needed if it reveals an eye problem that’s causing the uveitis.
 
If the animal doesn’t have an obvious eye abnormality causing the inflammation, the next step is to conduct diagnostic tests to find the cause. The animal will most likely have baseline blood tests, tests for various infectious organisms (especially viruses and the many organisms carried by fleas and ticks), and possibly x-ray imaging or ultrasound. The patient might need to be referred to a veterinary ophthalmologist.
 
Treatment
Uveitis is treated with medication to reduce inflammation. This medication is usually in the form of eye drops or eye ointment. Some animals need oral medication in addition to eye medication. The purpose of this anti-inflammatory medication is to relieve pain and reduce the risk of glaucoma. Whatever caused the uveitis also needs to be treated.
 
The prognosis for uveitis depends on the cause. If uveitis is diagnosed quickly and the underlying cause is treatable, the prognosis is generally good. Some conditions that cause uveitis have a more guarded prognosis.
 
Image source: Wall Boat on Flickr

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