Diagnosing and Treating Acute Anterior Uveitis, Part 2
Demographics, review of systems and laboratory testing can help uncover causes of acute anterior uveitis (AAU). Most causes of AAU are idiopathic, however, laboratory tests may reveal one of the many systemic conditions that can bring about an AAU. Here we'll look at the top seven causes of acute anterior uveitis to help in your differential diagnosis.
Searching for Answers
Juvenile rheumatoid arthritis (JRA) occurs between ages 3 and 16, mostly in females. Tests include anti-nuclear antibody (ANA), erythrocyte sedimentation rate (ESR) and X-rays of knees and other affected joints. All will be positive. Females exhibit a more chronic, indolent form of JRA. Screenings are suggested for all young females who have pauciarticular arthritis and are also positive for ANA and negative for rheumatoid factor.
Fuchs heterochromic iridocyclitis occurs at any age with no gender predilection. The iris heterochromia can be difficult to ascertain, especially when bilateral. You will usually note keratic precipitates scattered on the corneal endothelium with biomicroscopy. Laboratory testing is typically unnecessary.
Ankylosing spondylitis (AS) typically occurs between age 15 and 40, in a greater percentage of men. Nearly a quarter of AS patients demonstrate bilateral ocular involvement. Early in the disease, patients may complain of subtle back pain. However, the hallmark of AS is severe back pain with restricted motion. Radiographic laboratory findings after an anteroposterior view of the sacroiliac joints will reveal heightened radiodense areas.
Reiter's syndrome demonstrates the same age and gender predisposition as AS. It affects multiple systems, which gives rise to polyarthritis, conjunctivitis, urethritis, skin eruptions and oral ulcers. Like AS, laboratory tests such as HLA-B27 and ESR will be positive. Other tests may include urethral cultures, WBC count, radiography and a Chlamydia complement fixation test. Most cases of AAU are mild.
Testing for inflammatory bowel disease can begin with an ESR and HLA-B27 testing. In conjunction with an internist or gastroenterologist, other tests may include sigmoidoscopy, barium enema and a rectal biopsy.
Secondary and tertiary forms of syphilis may produce AAU. Two common tests include the VDRL and FTA-ABS. The VDRL becomes positive early in the disease course and shows a 99 percent sensitivity in secondary syphilis cases. Although in cases of late or latent syphilis, the sensitivity of VDRL decreases to 70 percent, an FTA-ABS has a sensitivity of 98 percent. Eyecare practitioners typically order these tests when they suspect syphilis-induced AAU. A lumbar puncture may also be ordered in seropositive cases that have lasted for more than a year.
Nearly one-fifth of patients with psoriatic arthritis (PA) will exhibit AAU. A positive HLA-B27 test along with psoriasis and arthritis are indicative of psoriatic arthritis. Recent work by Durrani and Foster (2005) indicates that psoriatic arthritis has distinct clinical features not found in more common HLA-B27 causes of AAU. More often the uveitis of psoriatic arthritis patients is bilateral, lasts longer and frequently requires an oral NSAID therapy. The uveitis in PA may also occur at a later age, corresponding with the increasing prevalence of psoriasis in older individuals.
A Look Ahead
Continued work in the area of immunogenetics will aid in the diagnosis, future testing and possible treatments of AAU in the years ahead.
Dr. Miller is on the faculty at the University of Houston College of Optometry. He is a member of the American Optometric Association and serves on its Journal Review Board. You can reach him at firstname.lastname@example.org.