Ankylosing spondylitis (AS) is a type of arthritis. It causes pain and stiffness, mainly in your spine. But it can also cause eye inflammation called uveitis. Left untreated, uveitis can harm your vision and, in some cases, lead to blindness.
What Is Uveitis?
Uveitis is a large group of inflammatory eye diseases. It gets its name from the fact that these diseases mostly strike the uvea, the middle part of your eye. But uveitis can show up almost anywhere inside the eye.
Doctors usually describe uveitis based on where you have it:
Anterior uveitis (also called iritis) happens in the front part of your eye. That includes the iris, the colored part. It’s the most common type of uveitis for people with AS. If it's not treated, anterior uveitis can lead to cataracts, glaucoma, or a buildup of fluid called retinal edema.
Intermediate uveitis is in the vitreous. That’s the big, fluid-filled space in your eye attached to your retina, a layer of cells that sense light and send signals to your brain.
Posterior uveitis (also called choroiditis) attacks the back of your eye. It may affect your retina and your optic nerve, which connects your eye to your brain.
Panuveitis affects all parts of your eye. It’s the most severe type. It can cause blindness if it's not treated.
Why People With AS Get It
About half of people with ankylosing spondylitis have uveitis at least once. It’s one of the most common complications of that form of arthritis.
Your eye doctor could actually be the first to figure out you have AS. That’s because the same inflammation that makes your back hurt can also cause inflammation in your eyes and other parts of your body.
Some experts think the inflammation starts in a place you might not think of: your gut.
It’s home to trillions of tiny organisms called microbes. They perform so many vital functions that you can’t live without them. One of their main jobs is to control your immune system. When the microbes get out of whack, your immune system does, too.
Uveitis may start when gut bacteria tell immune cells called T cells to attack your eyes. But that’s probably not the whole story. Many people with AS and anterior uveitis have a gene called HLA-B27. This gene makes eye inflammation much more likely.
Keep an eye out for:
- Blurred vision
- Sensitivity to bright light
These symptoms can come on quickly in one or both eyes. Sometimes uveitis is a one-time thing. In other cases, you may go years between flares. In still others, it can also be long-lasting and need ongoing treatment.
The goal of uveitis treatment is to ease inflammation fast. For anterior uveitis, doctors usually prescribe two types of eye drops:
- Steroid drops to lower inflammation
- Drops that widen your pupil to ease pain
For other types of uveitis, you may need steroid pills or shots around your eyes. Sometimes doctors implant a steroid capsule inside your eye.
Steroids can cause serious side effects, including eye diseases like glaucoma and cataracts. Usually, you won't use steroids for more than 3 months. As you taper off them, your doctor may start you on another medicine.
Some experts think a change in gut bacteria can ease uveitis. You might try:
Prebiotics. These plant fibers feed healthy bacteria in your gut and make them stronger. You can find them in from foods like bananas and onions.
Supplements for gut health like butyrate are another option. A diet that's mostly plant-based could also help.
Talk with your doctor to find out which treatment might work best for you.