Diagnosing a red eye: an allergy or an infection?

Abstract

A red eye is the cardinal sign of ocular inflammation, and is one of the most common ophthalmological complaints. Inflammation
of almost any part of the eye, including the lacrimal glands and eyelids, or a faulty tear film, can lead to a red eye. The condition is
usually benign, self-limiting and can be managed effectively in general practice. While there may be numerous causes of a red eye,
conjunctivitis is the most common. A thorough patient history and physical examination of the eye are essential in the management
of a red eye when differentiating between an allergic and an infectious cause.