The signs, symptoms and characteristics of uveitis include:

• Eye redness
• Eye pain
• Light sensitivity
• Blurred vision
• Dark, floating spots in your field of vision (floaters)
• Decreased vision

Symptoms may occur suddenly and get worse quickly, though in some cases, they develop gradually. They may affect one or both eyes.

The uvea is the middle layer of tissue in the wall of the eye. It consists of the iris, the ciliary body and the choroid. The choroid is sandwiched between the retina and the sclera. The retina is located at the inside wall of the eye and the sclera is the outer white part of the eye wall. The uvea provides blood flow to the deep layers of the retina. The type of uveitis you have depends on which part or parts of the eye are inflamed:

• Iritis (anterior uveitis) affects the front of your eye and is the most common type.
• Cyclitis (intermediate uveitis) affects the ciliary body.
• Choroiditis and retinitis (posterior uveitis) affect the back of your eye.
• Diffuse uveitis (panuveitis) occurs when all layers of the uvea are inflamed.

In any of these conditions, the jelly-like material in the center of your eye (vitreous) can become inflamed and infiltrated with inflammatory cells.

In about half of all cases, the specific cause of uveitis isn't clear. If a cause can be determined, it may be one of the following:

• Eye injury or surgery
• An autoimmune disorder, such as sarcoidosis or ankylosing spondylitis
• An inflammatory disorder, such as Crohn's disease or ulcerative colitis
• An infection, such as cat-scratch disease, herpes zoster, syphilis, toxoplasmosis, tuberculosis, Lyme disease or West Nile virus
• A cancer that affects the eye, such as lymphoma

People with changes in certain genes may be more likely to develop uveitis. In addition, a recent study shows a significant association between uveitis and cigarette smoking.

Left untreated, uveitis can cause complications, including:

• Glaucoma
• Cataracts
• Optic nerve damage
• Retinal detachment
• Permanent vision loss