Uveitis is inflammation of the uvea, the middle layer of your eye’s wall. It can cause eye pain, redness, blurred vision, and sensitivity to light, and without treatment it can lead to serious complications including vision loss. Uveitis affects roughly 261 out of every 100,000 people in the United States, making it uncommon but far from rare.
The Uvea and What It Does
To understand uveitis, it helps to know what the uvea actually is. Your eye has three main layers. The outermost is the sclera, the tough white part you can see. The innermost is the retina, which detects light. Sandwiched between them is the uvea, made up of three connected structures that each serve a different purpose.
The iris is the colored ring at the front of your eye. It’s a muscle that widens and narrows your pupil to control how much light gets in. Behind it sits the ciliary body, a ring of tissue whose muscles change the shape of your lens so you can focus on objects at different distances. The ciliary body also produces the fluid that fills the front of your eye and helps it hold its shape. The largest part of the uvea is the choroid, a thin sheet of tissue packed with blood vessels that wraps around the back of your eyeball, supplying oxygen and nutrients to the retina.
When any of these structures becomes inflamed, that’s uveitis. Because the uvea is rich in blood vessels and sits right next to critical structures like the retina and lens, inflammation here can cause damage that spreads beyond the uvea itself.
Types Based on Location
Uveitis is classified by where in the eye the inflammation occurs. The type determines both the symptoms you experience and how it’s treated.
- Anterior uveitis affects the front of the eye, primarily the iris. This is the most common form. It tends to come on suddenly with eye pain, redness, and light sensitivity.
- Intermediate uveitis involves the ciliary body and the gel-like fluid (vitreous) in the center of the eye. It often causes floaters and blurred vision more than pain.
- Posterior uveitis targets the choroid at the back of the eye, near the retina. Because it affects the area responsible for central vision, it can cause significant visual disturbance.
- Panuveitis means all three parts of the uvea are inflamed at once. This is typically the most serious form.
What Causes It
In about half of all cases, no specific cause is ever identified. When that happens, it’s often considered an autoimmune process where the body’s immune system mistakenly attacks eye tissue.
When a cause is found, it usually falls into one of two categories: autoimmune conditions or infections. On the autoimmune side, several inflammatory diseases are linked to uveitis. These include sarcoidosis, lupus, inflammatory bowel disease, Behçet’s disease, and ankylosing spondylitis (a type of spinal arthritis where uveitis is one of the most common complications). A specific genetic marker called HLA-B27 is associated with inflammatory arthritis conditions that raise uveitis risk.
Infections can also trigger uveitis. Viruses like herpes simplex, varicella-zoster (the virus behind chickenpox and shingles), and cytomegalovirus are known culprits. Bacterial infections including syphilis and tuberculosis, as well as parasitic infections like toxoplasmosis, can cause it too. Infection-related uveitis typically affects only one eye at a time, while autoimmune-related uveitis more often involves both.
Symptoms and How They Develop
Acute uveitis, particularly the anterior type, tends to develop quickly. You might wake up one morning with a red, painful eye that’s sensitive to light. Your vision may be blurry, and you might notice your pupil looks smaller than the other eye’s pupil. These symptoms can intensify over hours to days.
Intermediate and posterior uveitis develop more gradually. You’re more likely to notice floaters (dark spots or threads drifting across your vision) and a slow decline in visual clarity. Pain and redness are less prominent with these types, which means they sometimes go unnoticed until vision has already been affected. This is part of what makes posterior uveitis particularly concerning: it can quietly damage the retina before you realize something is wrong.
How It’s Diagnosed
An eye doctor can usually identify uveitis during an office visit using several standard tools. A slit-lamp exam, which shines an intense line of light into the front of your eye under magnification, reveals inflammatory cells floating in the fluid of the eye. This is the primary way anterior uveitis is detected.
To check the back of the eye, the doctor will dilate your pupils with drops and use a bright light to examine the retina and choroid directly. Eye pressure is measured because uveitis can raise or lower it. For more detailed views, optical coherence tomography (OCT) creates a cross-sectional map of the retina and choroid, revealing swelling that might not be visible otherwise. In some cases, a special dye is injected into a vein in your arm to photograph blood flow in the eye, helping to pinpoint areas of inflammation or leaking vessels.
Because uveitis is so often linked to underlying conditions, your eye doctor may order blood tests or refer you to other specialists to look for autoimmune diseases or infections driving the inflammation.
Treatment and What to Expect
The core goal of treatment is to reduce inflammation, relieve pain, prevent tissue damage, and restore vision. What that looks like depends on where and how severe the inflammation is.
For most cases of acute anterior uveitis, steroid eye drops are the first line of treatment. You’ll typically start with frequent dosing, sometimes as often as every hour, then gradually taper down over several weeks. A common regimen runs about four to five weeks total, stepping down from hourly drops to once daily before stopping. Your doctor will likely want to see you every week or two during active disease until the inflammation has been quiet for at least two weeks.
Intermediate and posterior uveitis usually need more than drops alone, since the inflammation sits deeper in the eye. Options include steroid injections around or inside the eye, or oral steroid medication. If oral steroids are needed for more than a few months, doctors generally transition to other immune-suppressing medications to avoid the well-known side effects of long-term steroid use, such as weight gain, bone thinning, and elevated blood sugar.
For people with chronic or severe disease that doesn’t respond well to initial treatment, systemic immunosuppressive therapy becomes important. This is especially true when both eyes are involved, when central vision is threatened, or when steroids can’t be reduced to a safe long-term dose.
Acute, Chronic, and Recurrent Patterns
Uveitis doesn’t follow one predictable path. Some people have a single episode that resolves completely with treatment and never returns. Others develop a recurrent pattern where flare-ups happen weeks, months, or even years apart, separated by periods of quiet. A third group develops chronic uveitis, where low-grade inflammation persists and requires ongoing treatment to keep it in check.
The tricky part is that even after a flare resolves, the blood vessels inside the eye may have undergone permanent changes, and immune memory means the potential for relapse is always present. This is why follow-up visits matter even when your eye feels completely normal.
Complications Worth Knowing About
Untreated or poorly controlled uveitis can lead to several serious eye problems. Cataracts are one of the most common complications, developing at a rate of roughly 5.4 per 100 eye-years in people with anterior uveitis. The risk varies significantly with disease severity. People with lower-risk profiles have about a 6% chance of developing a cataract within five years, while those with chronic or more severe disease face a 38% chance over the same period. At 15 years, the highest-risk group sees that number climb to 55%.
Glaucoma is another concern, because inflammation can disrupt the drainage system that regulates eye pressure. Macular edema, which is swelling in the central part of the retina responsible for sharp vision, is a common complication of intermediate and posterior uveitis and a leading cause of vision loss in these patients. In the most severe and prolonged cases, the eye can shrink and lose function entirely, a condition called phthisis bulbi.
These risks underscore why early treatment and consistent follow-up are so important. Most people with uveitis who receive prompt care retain good vision, but the condition demands attention each time it flares.