Seasonal variation of acute anterior uveitis: differences between HLA-B27 positive and HLA-B27 negative disease.

One hundred and seventy-five consecutive patients with acute anterior uveitis (AAU) were examined over a 24-month period. There was a significantly increased incidence of AAU during the months August to December (p less than 0.05). This increase was confined predominantly to the HLA-B27 negative group of patients (p less than 0.01). There was no significant monthly difference in incidence between males and females, between patients with first or recurrent attacks, or between patients with and without arthritis. These results suggest that seasonal environmental factors may play a role in the production of HLA-B27 negative AAU.