Inefficacy or paradoxical effect? Uveitis in ankylosing spondylitis treated with etanercept.

Ankylosing spondylitis (AS) is presented with axial and peripheral articular involvement. Uveitis is a severe and rather specific manifestation of AS. Biologics targeting tumor necrosis factor (TNF) α are effective on both articular and ocular manifestations of disease. The occurrence of uveitis in patients that never had eye involvement or the relapse of uveitis is described during anti-TNF α treatment. The frequency of these events is slightly higher during therapy with etanercept. The available TNF α blockers show different pharmacokinetics and pharmacodynamics yielding different biological effects. There is an ongoing debate whether uveitis during anti-TNF α has to be considered as paradoxical effect or an inadequate response to therapy. Here, we present a case report and review what the evidences for the two hypotheses are.