Red eye for the internist: when to treat, when to refer.

When a patient presents with redness in the eye, the cause needs to be diagnosed quickly. Some of the diseases that cause redness in the eye can be initially managed by an internist, but others call for quick referral to an ophthalmologist. This article reviews the spectrum of conditions manifesting as a red eye, emphasizing how to differentiate between the benign and the vision-threatening.