Causes of uveitis

Uveitis occurs when the eye becomes inflamed.

Inflammation is when areas of the body become warm, red and swollen in response to an illness or infection.

Most cases of uveitis are thought to be related to a problem with the immune system (the body's defence against infection and illness).

If the specific cause of uveitis is not identified, it is known as idiopathic uveitis. But most experts suspect idiopathic uveitis is also related to a problem with the immune system.

Immune system problems

Uveitis often develops in people who have an underlying autoimmune condition (where the immune system mistakenly attacks healthy tissue).

Autoimmune conditions known tocause uveitis in some people include:

• Ankylosing spondylitis a condition mainly affecting the spine
• reactive arthritis a type of arthritis often affecting the joints, genitals and eyes
• conditions that cause bowel inflammation such as Crohn's disease and ulcerative colitis
• psoriasis a skin condition caused by the immune system disrupting the normal production of skin cells
• multiple sclerosis a condition mainly affecting the nerves
• Behet's disease a rare condition that causes mouth ulcers and genital ulcers
• sarcoidosis a rare inflammatory condition affecting the lungs, skin and eyes

Infection

Uveitis can also be caused by an infection, such as:

• toxoplasmosis an infection caused by parasitic germs spread in raw meat and soil
• herpes simplex virus the virus responsible for cold sores
• varicella-zoster virus the virus that causes chickenpox and shingles
• cytomegalovirus a common infection that doesn't usually cause any noticeable symptoms in most people, but can cause sight-threatening uveitis in people with a lowered immune system
• tuberculosis this can lead to uveitis, either during the infection or after it's been treated
• HIV and syphilis are rare causes

Other causes

Uveitis can also be caused by:

• trauma or injury to the eyes, or eye surgery
• some types of cancers, such as lymphoma ,although this is a very rare cause of uveitis
• sometimes no cause can be found

Can I inherit uveitis?

Uveitis can't be passed down through the family because there's no gene that causes the condition.

However, your genes may make you more susceptible to developing the condition.