Acute iritis (anterior uveitis) often presents in a similar fashion to some corneal diseases with symptoms of pain, tenderness, photophobia and lacrimation. Careful external inspection with a pen torch and topical fluorescein can rule out most corneal conditions eg dendritic ulcers, abrasions and foreign bodies.
Slit-lamp biomicroscopy is, however, required to establish a diagnosis of iritis, which is characterised by keratin precipitates “dusting” the corneal endothelium, inflammatory cells and flare in the anterior chamber. In addition there is occasionally elevated intraocular pressure and posterior synechiae resulting in pupil irregularities.
Severe iritis can result in a proteinaceous fibrin material in the anterior chamber which may gravitate inferiorly to form a hypopyon. Dilated fundoscopy is required to rule out associated posterior segment conditions eg Behcet syndrome, sarcoidosis.
Most cases of anterior uveitis are sterile inflammatory reactions of unknown cause. Treatment is usually with intensive topical steroids (and/or mydriatics) which need to be tailed off slowly over a period of 4-6 weeks. Recurrences are fairly common, especially in patients who are HLA-B27 positive.