Bacterial and viral infections of the eye

A patient with a red eye due to infection is likely to present to his or her GP. An accurate diagnosis and prompt and appropriate treatment can be sight saving.

Key Points

Conjunctivitis is a common cause of a red eye. Suspect bacterial conjunctivitis in any patient with bilateral sticky red eyes. A persistent conjunctivitis with a watery discharge and preauricular lymphadenopathy is most likely to be caused by adenovirus and is very contagious.
Bacterial conjunctivitis usually responds well to topical antibiotics.
Bacterial keratitis threatens vision and must be excluded in any patient who presents with a red eye with a corneal opacity. Contact lens wearers are at particular risk.
Herpes simplex can cause conjunctivitis, but disease recurrence causes a keratitis with typical dendritic corneal ulcers that stain with fluorescein. Keratitis is best treated with topical aciclovir.
Herpes zoster ophthalmicus is likely to involve the eye when the rash appears on the nose or in the medial canthus.
Eye involvement in herpes zoster ophthalmicus requires systemic therapy with aciclovir, famciclovir or valaciclovir.

Sunday 26 July 2026

Bacterial and viral infections of the eye

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