Our immune system protects us from infection. Sometimes immune cells may “act up” against our body’s own cells, in the absence of infection. Such an “acting up” against our own cells is called autoimmune disease. Autoimmune disease affecting the eye is called uveitis.
Many different types and forms of uveitis exist. One of the more common types of uveitis is called “HLA-B27 recurrent anterior uveitis.”
Now, let’s look at the meaning of each of those words.
Every immune cell in our body carries a fingerprint. That immune fingerprint is called the “HLA type.” For example, people who have organ transplants must have an “HLA match” with the donor of their organ.
The HLA fingerprint has 3 main parts: HLA-A, HLA-B, and HLA-C.
We know that people who have the HLA-B27 fingerprint are more prone to having uveitis, specifically, recurrent anterior uveitis. Something about the B27 fingerprint (and that exact “something” is not known) predisposes to uveitis.
“Recurrent” means a patient may have repeat episdoes of inflammation. These episodes may occur a few months apart, or they may occur years apart. Every patient is different and there are no hard and fast rules for how often a particular patient may have repeat episodes of inflammation.
“Anterior uveitis” means that the inflammation mainly affects the front one-third of the eye. However, the back two-thirds of the eye may be affected, either directly or indirectly. B27 uveitis tends to affect one eye at a time, but can affect either eye with a recurrence (in other words a recurrence does not have to be in the same eye).
How does B27 uveitis take away vision? B27 uveitis may cause an inflammation-related cataract. B27 uveitis may cause inflammation-related glaucoma. B27 uveitis may cause adhesions in the front of the eye, known as “posterior synechiae” that may disrupt the round shape of the pupil. B27 uveitis may cause retinal swelling, or macular edema.
How do we treat B27 uveitis? Think of a ladder. The first step on the ladder is steroid drops (“white top” bottle). We may also prescribe dilating drops (“red top” bottle). If drops are not sufficient, we may go a step up the ladder and give a steroid injection under the skin layer of the eye. A steroid injection packs “extra punch” compared to steroid drops. We may sometimes also prescribe steroid pills to take by mouth.
The philosophy behind treatment is to quiet the inflammation as quickly as possible. When the inflammation runs for too long, the eye can develop anatomical repercussions: cataract, glaucoma, adhesions, retinal edema, all of which may affect vision, often in an irreversible fashion.
At the same time, the steroid drops, injections, and pills do have side effects, namely steroid-glaucoma and steroid-cataract. Steroid injections may also cause “puffy eyelids.” Steroid pills may also cause problems elsewhere in the body: weight gain, high sugars, high blood pressure, calcium loss from bones, difficulty sleeping, etc. So we try to “walk a fine line”: we work to quiet down the inflammation with our medicines to minimize the damage the inflammation inflicts on the eye; at the same time we try not to “overtreat” with steroids to minimize the side effects of steroids on the eye.
If a patient with B27 tends to flare often and we are starting to see inflammation related problems in the eye, or we are starting to get a lot of side effects from steroids, we my advise the use of a non-steroid “immune-modulatory” drug. These medicines can be taken for longer time periods without the side effects of steroids. These medications are borrowed from the field of organ transplantation and include methotrexate, azathioprine (Imuran), mycophenolate (Cellcept), cyclosporine, infliximab (Remicade), daclizumab (Zenapax), and others. These medicines do have their own possible side effects and a patient on these medications needs to be monitored in conjunction with an internal medicine doctor while on the medications. In general, however, when we recommend these medications, we believe the potential benefit of the medicines in preserving vision justifies the risk of side effects of the medicines.
A last note: patients with the B27 uveitis may have autoimmune problems elsewhere in the body. They have autoimmune bowel disease that may cause bloody or irregular stools or other bowel problems. They may have autoimmune joint disese, often affecting the lower back (“sacroillitis”). Please let us know about any other “events” going on elsewhere in your body, as there may be a relationship to the eye.