Patient with iritis will typically present with a painful red eye and it can sometimes be difficult to tell if it is due to conjunctivitis or a corneal abrasion. Some tips that can help differentiate iritis from other causes of painful red are:
When pain reduction was used as a diagnostic tool, it had a sensitivity of 80% and a specificity of 86% in determining whether a simple corneal injury was present. In iritis, the pain will NOT be relieved with topical anesthetic.
In iritis, injection will be localized predominantly around the iris and not diffusely over the conjunctiva.
The consensual light reflex can be used to make the diagnosis. Of course, shining a light in the affected eye will cause pain, but in iritis shining a light in the normal, unaffected eye (by causing consensual movement of the other affected iris) will cause pain if iritis is present.
Finally, ensure you document:
Visual Acuity corrected in both eyes. Use a pinhole if they forgot their glasses.
That you flipped their eyelids to make sure that no foreign bodies are lurking under the lids
Stain their eyes with flouriscen to ensure there are no corneal abrasions in addition to the iritis.
References
Adapted from Pfaff J and Moore G. Eye, Ear, Nose and Throat. Emergency Medicine Clinics of North America. Volume 15, Issue 2 (May 1997)
