Although most forms of infective and allergic conjunctivitis are not serious, some forms can, if not diagnosed early, lead to loss of sight or systemic morbidity. An understanding of the various causes of conjunctivitis and also the differential diagnosis of ‘the red eye’ helps to avoid missing these serious diagnoses and allows the opportunity to treat them in a timely manner when diagnosed.
Confronted with a patient with a red eye, more often than not the diagnosis is conjunctivitis. However, an automatic diagnosis of ‘conjunctivitis’ is often made without enquiry or consideration of possible alternatives. Treatment too often appears to be a ‘trial of chloramphenicol’ with or without topical corticosteroids, with referral if the red eye does not resolve. Although for most ‘conjunctivitides’ a short course of this empirical treatment may not harm the eye or alter the visual or systemic prognosis, for some entities a prolonged delay in appropriate investigation and treatment can be devastating.
A better understanding of the various types of conjunctivitis and also the differential diagnosis of ‘the red eye’ is imperative for better diagnosis and appropriate therapy and to avoid missing a potentially blinding or life-threatening illness.