For The General Practitioner Sponsors do not influence content. A red eye is a cardinal sign of ocular inflammation, which can be caused by several conditions.
Most cases are benign and can be managed effectively by the primary care provider.
The key to management is recognizing cases with underlying disease that require ophthalmologic consultation. A red eye is caused by dilation of blood vessels in the eye. Diagnosis may be aided by the differentiation between ciliary and conjunctival injection. Ciliary injection involves branches of the anterior ciliary arteries and indicates inflammation of the cornea, iris, or ciliary body. Conjunctival injection mainly affects the posterior conjunctival blood vessels.