Ankylosing spondylitis (AS) is an inflammatory disease. It causes pain, swelling, and stiffness in the joints. It mainly affects your spine, hips, and areas where ligaments and tendons connect to your bones. Advanced AS may cause new bone to form in the spine and lead to spinal fusion.

While AS inflammation is common in the spine and large joints, it may also occur in other areas of the body, such as the eyes. About 40 percent of people with AS develop eye inflammation. This condition is known as uveitis.

Uveitis often affects the iris, the colored ring around your pupil. Because the iris is in the middle part of your eye, uveitis is often referred to as anterior uveitis. Less frequently, uveitis may affect the back or other areas of your eye, which is called posterior uveitis.

Keep reading to learn why uveitis happens, how to identify it, your treatment options, and more.

AS is a systemic disease, which means it may impact multiple areas of the body and cause widespread inflammation.

The HLA-B27 gene may also be a factor. This gene is common to most people who have AS or uveitis. Other conditions that share the gene include inflammatory bowel disease and reactive arthritis.

Uveitis may be the first sign that you have a systemic condition such as AS. Uveitis may also occur independently of another inflammatory condition.

Learn more: HLA-B27 »

Uveitis usually impacts one eye at a time, although it can develop in both eyes. It may happen suddenly and become severe quickly, or it can develop slowly and worsen over several weeks.

The most obvious symptom of uveitis is redness in the front of the eye.

Other symptoms include:

  • eye swelling
  • eye pain
  • sensitivity to light
  • blurred or cloudy vision
  • dark spots in your vision (also known as floaters)
  • decreased vision

Most cases of uveitis are diagnosed by a review of your medical history and a thorough eye exam.

An eye exam typically includes the following:

  • eye chart test to determine if your vision has declined
  • fundoscopic exam, or ophthalmoscopy, to examine the back of the eye
  • ocular pressure test to measure eye pressure
  • a slit lamp exam to examine most of the eye, including the blood vessels

If a systemic condition such as AS is suspected, your doctor may order imaging tests, such as an X-ray or MRI, to view your joints and bones.

In some cases, your doctor may also order a blood test to check for the HLA-B27 gene. A positive test result doesn’t necessarily mean you have AS, though. Many people have the HLA-B27 gene and don’t develop an inflammatory condition.

If it’s not clear why you have uveitis, your doctor may order additional blood tests to determine if you have an infection.

The treatment plan for AS-related uveitis is twofold. The immediate goal is to decrease eye inflammation and its effects. It’s also important to treat AS overall.

The first line of treatment for uveitis is anti-inflammatory eyedrops, or eyedrops that contain a corticosteroid. If those don’t work, corticosteroid pills or injections may be needed. If you’re dependent on corticosteroids, your doctor may add an immunosuppressant medication to allow steroid tapering.

Severe uveitis may require a procedure to remove some of the gel-like substance in the eye, which is known as the vitreous.

Surgery to implant into the eye a device that releases corticosteroid medication over an extended period may be recommended if you have chronic uveitis that doesn’t respond to other treatments.

If you have AS, it’s important to manage your symptoms to reduce the risk of developing complications such as uveitis. AS remedies aim to reduce joint pain and inflammation.

Treatments vary, but typical options include:

  • nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil)
  • biologic medications, such as an interleukin-17 inhibitor or tumor necrosis factor blocker
  • physical therapy
  • hot and cold therapy
  • lifestyle changes, such as getting regular exercise, trying an anti-inflammatory diet, and quitting smoking

Uveitis is uncomfortable at best. It’s not a condition you should ignore. Uveitis typically won’t clear up over time or with over-the-counter eye drops. It requires evaluation and treatment by an ophthalmologist or optometrist.

Many uveitis cases are successfully treated with medications and consistent eye care. The sooner you start treatment, the lower your risk for long-term complications.

Complications can include:

  • cataracts
  • scar tissue, which may cause pupil irregularity
  • glaucoma, which increases pressure in the eye and can cause vision loss
  • decreased vision from calcium deposits on the cornea
  • swelling of the retina, which may cause vision loss

Uveitis may be hard to control, especially if it’s caused by AS or another systemic inflammatory condition.

Since there are many factors involved, it can be difficult to predict how long it will take for uveitis to go away. Severe uveitis or uveitis of the back of the eye usually take longer to heal. The condition may come back after treatment.

Be sure to follow your doctor’s treatment recommendations. You should let your doctor know immediately if your symptoms worsen or recur.

Learn more: Ankylosing spondylitis »

It’s always important to protect your eyes from UVA and UVB rays as well as environmental hazards. If you have uveitis, however, it’s doubly important to pamper your eyes.

The National Eye Institute recommends these general tips for keeping your eyes healthy:

  • Get an annual eye exam.
  • Wear sunglasses that protect your eyes from UVA and UVB rays.
  • If you’re sensitive to light, wear sunglasses indoors or keep the lights dim.
  • Look away from your computer, cell phone, or television for at least 20 seconds every 20 minutes to help prevent eyestrain.
  • Wear protective eyewear if you work with hazardous materials or in a construction environment.
  • Wear protective eyewear while playing sports or doing housework.
  • Quit smoking, as smoking accelerates nerve damage in the eye and other eye conditions.

Tips for people who wear contact lenses:

  • Wash your hands frequently and before inserting contact lenses.
  • Don’t wear contact lenses while your eyes are inflamed.
  • Avoid rubbing your eyes or touching your hands to your eyes.
  • Disinfect your contact lenses regularly.

Keep reading: How does arthritis affect the eyes? »