The red eye.

The nonophthalmic physician confronted by a patient with a red eye should be able to distinguish common microbial or allergic conjunctivitis from potentially blinding disorders, such as acute angle closure glaucoma, uveitis, or herpes simplex keratitis, and should remain alert for an associated systemic disease, such as rheumatoid arthritis, polycythemia, or carotid cavernous fistula. The physician should approach the red eye systematically: take a careful history, including type of pain; measure visual acuity; observe the pattern of redness, the type of discharge, the shape of the pupil, and the opacities of the media; and measure the intraocular pressure.