Possible ankylosing spondylitis in acute anterior uveitis.

HLA-B27 typing of 103 acute anterior uveitis (AAU) patients showed that 49 (48%) were positive for this antigen. Of these HLA-B27 positive AAU patients, 27 (55%) had ankylosing spondylitis (AS) according to the New York criteria. The 22 HLA-B27 positive AAU patients without AS, however, also showed symptoms and signs of AS. Seventeen (77%) of these 22 HLA-B27 positive AS negative AAU patients fulfilled a set of criteria for classification as possible AS. In the group of 54 HLA-B27 negative AAU patients, only two patients (4%) had AS. Of the remaining 52 patients only seven (13%) had possible AS. Of the 21 patients having posterior uveitis (PU) none was HLA-B27 positive nor met the criteria for AS or possible AS. These findings indicate a strong relationship between AAU, AS or possible AS and HLA-B27 and suggest that HLA-B27 typing in AAU patients is important for early diagnosis of AS.