HL-A 27 and acute anterior uveitis.

51 (30 men and 21 women) of 90 consecutive patients with acute non-granulomatous anterior uveitis were HL-A 27 positive. This frequency of 55-7 per cent compares with 8-2 per cent in controls. Twenty-three patients (18 men and 5 women) had in addition evidence of systemic disease, including ankylosing spondylitis, sacroiliitis and Reiter's syndrome, sometimes associated with psoriasis. Twenty-eight of 63 patients without evidence of systemic disease were HL-A 27 positive, suggesting that the uveitis in many of these cases has a similar aetiology to those with rheumatic disease. The uveitis associated with HL-A 27 is typically unilateral, associated with mechanical ptosis, and a painful diffusely red, photophobic, and lacrimating eye, generally lasting 3 weeks or more. Protein extravasation into the aqueous is considerable, cells are usually present in the aqueous and anterior vitreous, and keratic precipitates are never mutton fat in appearance. Recurrent episodes are characteristic. The association with HL-A 27 suggests that many if not most cases of non-granulomatous anterior uveitis have a close aetiological relationship to ankylosing spondylitis and Reiter's syndrome and it is likely that infective agents, leading to an unusual immunologically mediated inflammatory response in predisposed individuals, are involved. Ten patients with granulomatous anterior uveitis were HL-A 27 negative.