Causes

Often, the cause of iritis can't be determined. In some cases, iritis can be linked to eye trauma, genetic factors or certain diseases. Causes of iritis include:

• Injury to the eye. Blunt force trauma, a penetrating injury, or a burn from a chemical or fire can cause acute iritis.

• Infections. Viral infections on your face, such as cold sores and shingles caused by herpes viruses, can cause iritis.

  Infectious diseases from other viruses and bacteria can also be linked to uveitis. For instance, they may include toxoplasmosis, an infection most often caused by a parasite in uncooked food; histoplasmosis, a lung infection that occurs when you inhale spores of fungus; tuberculosis, which happens when bacteria enters the lungs; and syphilis, which is caused by the spread of bacteria through sexual contact.

• Genetic predisposition. People who develop certain autoimmune diseases because of a gene alteration that affects their immune systems might also develop acute iritis. Diseases include a type of arthritis called ankylosing spondylitis, reactive arthritis, inflammatory bowel disease and psoriatic arthritis.
• Behcet's disease. An uncommon cause of acute iritis in Western countries, this condition is also characterized by joint problems, mouth sores and genital sores.
• Juvenile rheumatoid arthritis. Chronic iritis can develop in children with this condition.
• Sarcoidosis. This autoimmune disease involves the growth of collections of inflammatory cells in areas of your body, including your eyes.
• Certain medications. Some drugs, such as the antibiotic rifabutin (Mycobutin) and the antiviral medication cidofovir, that are used to treat HIV infections can be a rare cause of iritis. Rarely, bisphosphonates, used to treat osteoporosis, can cause uveitis. Stopping these medications usually stops the iritis symptoms.