By Robert M. Beardsley, M.D.
Inflammation involving your eyes can take many forms. Your eyes can be pink, watery and itchy from allergies (IgE response); painful, goopy and red from conjunctivitis (infectious causes); and scratchy and red from foreign substances getting in the eyes, such as sawdust or metal. There is also a cause that has nothing to do with external sources such as dirt, pollen, or viruses, but with your own immune system misfiring. This is called uveitis.
As a uveitis specialist, I see all kinds of ocular inflammation from any number of sources. Uveitis merely means inflammation of your uvea. The uvea is a layer in the eye with blood vessels and dark pigment. Apparently, to the old-time pathologists, this part of the eye looked like a bunch of grapes under the microscope, hence the name uvea, Latin for â€œgrape.â€ So, what uveitis really boils down to is inflammation of your grape! Your immune system helps to protect you from external threats (like infections) as well as internal threats (like cancer). When your white blood cells misidentify your normal proteins as something it thinks is foreign, it will attack it with gusto and lead to inflammation. This can manifest in places like your joints (arthritis), skin (cellulitis) or eyes (uveitis).
Uveitis is broken down by the location of the inflammation within the eye. This can be anterior (affecting the front part of the eye, also called iritis), intermediate (middle part of the eye also called vitritis), or posterior (back part of the eye involving the retina and choroid). While not technically uveitis (since it is non-grape involving), the wall of the eye can also be inflamed. This condition is called scleritis. The location of the inflammation (the wall, front, middle or back) will determine the symptoms, possible causes and treatment.
There is a host of causes for uveitis. As stated above, anything that causes your immune system to misfire can lead to uveitis. This can be infections including TB, viruses or fungus. Also, systemic disease with eye manifestations like sarcoidosis, Wegenerâ€™s disease or Behcetâ€™s disease can lead to uveitis. Genetic factors play a role as well, as 6-8% of the population has a misfolded protein called HLA-B27 that makes uveitis more likely. In rare instances, cancer can also cause uveitis. Thus, an accurate diagnosis involves a careful history check, close examination and at times, diagnostic tests. One of the favorite parts of my job as a uveitis specialist is to ask people seemingly random non-eye related questions in my search for a systemic cause to their disease, such as, â€œDo you have mouth ulcers?â€ â€œDo you have circular rashes on your torso?â€ â€œAre you having trouble breathing?â€ Occasionally, a simple question can lead to a diagnosis that has implications far beyond the patientâ€™s eye health. Questions about factors as disparate as place of birth, recent travel, foods consumed and common infection can all lead to an accurate diagnosis.
Read more about uveitis and common causes of anatomic breakdown in Dr. Beardsleyâ€™s next article.