Uveitis

Uveitis occurs when the middle layer of the eyeball gets inflamed. This layer, called the uvea, has many blood vessels that nourish the eye. Uveitis can damage vital eye tissue, leading to permanent vision loss.

The uvea is the middle layer of the eye between the sclera (white part of the eye) and the retina (light-sensitive layer at the back of the eye). It has 3 parts:

• Iris (the colored part of the eye)
• Ciliary body (the part of the eye that helps the lens focus)
• Choroid (the part of the eye that connects the retina to the sclera)

Uveitis is not a single disease. Similar to arthritis (joint inflammation), uveitis can be a part of many different disease processes. Different types of uveitis often follow characteristic patterns that are distinguished by factors such as part of the eye that is affected, if the inflammation involves one or both eyes, or if the inflammation began suddenly or gradually.

Four types of uveitis

There are 4 types of uveitis. They are based on which part of the uvea is primarily affected.

• Inflammation primarily in the front of the eye is called anterior uveitis. It's the most common type. It usually starts suddenly and symptoms can last many weeks. Some forms of anterior uveitis are ongoing, while others go away but keep coming back.
• Inflammation primarily in the middle part of the eye is called intermediate uveitis. Intermediate uveitis affects the ciliary body and the vitreous (gel-like fluid that fills the eye). Symptoms can last for a few weeks to many years. This form can go through cycles of getting better, then getting worse.
• Inflammation involving the retina and the choroid at the back of the eye is called posterior uveitis. Symptoms can develop gradually and last for many years.
• In severe cases, all layers may be involved, panuveitis affects all parts of the uvea, from the front to the back of the eye.

What causes uveitis?

The cause may not always be clear. However, causes and risk factors include:

• Infections such as shingles virus, herpes simplex virus, syphilis, Lyme disease, tuberculosis, and parasites such as toxoplasmosis.
• An auto-immune or systemic inflammatory disease such as sarcoidosis, ankylosing spondylitis, inflammatory bowel disease (IBD), rheumatoid arthritis or lupus
• an eye injury or surgery
• Smoking 
• Certain medications
• Very rarely, a cancer that affects the eye, such as lymphoma
• Certain genes

Symptoms

Uveitis can develop suddenly. Symptoms can include:

• Eye redness, with or without pain
• Eye pain
• Light sensitivity
• Blurred vision
• Decreased vision
• Floaters (specks or moving clouds in your vision) 

Diagnosis

Evaluation for uveitis includes a detailed, complete eye exam and a thorough review of health history. Since uveitis is often connected with other diseases or conditions, various diagnostic tests may be needed. These may include blood or urine tests, examination of eye fluids, and imaging tests, such as X-rays and MRI scans. If there is a possible underlying condition as the cause of uveitis, referral to another specialist for further evaluation including general medical examination and additional laboratory tests may be necessary.

Treatment

Uveitis needs to be treated timely to prevent lasting problems. Treatment often includes eye drops that reduce inflammation (corticosteroids, non-steroidal anti-inflammatories) and widen (dilate) the pupil, which also help reduce eye pain and light sensitivity. In some cases, there may be a need for eye injections or additional systemic treatment. In some cases, uveitis specialist will work and co-manage with other specialists including rheumatologists to help treat the condition.

If uveitis is caused by an underlying condition, treatment may focus on that specific condition. Usually, the treatment for uveitis is the same regardless of the associated cause, as long as it is not infectious. The goal of treatment is to resolve the inflammation in the eye, as well as in other parts of the body, if present. In some cases, treatment may last for months to years.