Red eye unresponsive to treatment.

Red eyes that fail to respond quickly and completely to topical antibiotic treatment require more extensive evaluation to relieve the symptoms and avert possible sight-threatening complications. The initial differential diagnosis of red eye, which includes iritis, acute glaucoma, keratitis and corneal ulcer, and rarer disorders, must be reexamined. A commonly misdiagnosed cause of red eye is the dry eye syndrome. As a primary or secondary problem, the dry eye syndrome must be treated appropriately to avert sight-threatening complications and to alleviate substantial discomfort. The dry eye syndrome may represent the presenting sign of Sjögren's syndrome or it may be due to medication use, with important systemic and ocular implications.