Definition

Red eye is a common problem that can affect one or both eyes. The redness associated with red eye comes from blood vessels on the surface of your eye that are expanded (dilated) due to some form of irritation or infection.

Causes

• Allergies
• Blepharitis (eyelid inflammation)
• Chalazion (a type of cyst on your eyelid)
• Complication from a recent eye surgery
• Contact lens complication
• Corneal abrasion (scratch): First aid
• Corneal herpetic infections (herpes)
• Corneal ulcer
• Dry eyes (decreased production of tears)
• Ectropion (outwardly turned eyelid)
• Entropion (inwardly turned eyelid)
• Episcleritis (inflammation of the membrane covering the white part of the eye)
• Eyedrops side effect or complication
• Foreign object in the eye: First aid
• Glaucoma (group of conditions that damage the optic nerve)
• Hay fever (allergic rhinitis)
• Injury, such as from a blunt trauma or burn
• Iritis (inflammation of the colored part of the eye)
• Keratitis (inflammation of the cornea)
• Orbital cellulitis (severe infection of tissues around the eye)
• Pink eye (conjunctivitis)
• Scleritis (inflammation of the white part of the eye)
• Sty (a red, painful lump near the edge of your eyelid)
• Subconjunctival hemorrhage (broken blood vessel in eye)
• Uveitis (inflammation of the middle layer of the eye)

When to see a doctor

Seek emergency medical care

Call 911 or your local emergency number for red eye if:

• Your vision changes suddenly
• It is accompanied by severe headache, eye pain, fever or unusual sensitivity to light
• You also experience nausea or vomiting
• It is caused by a foreign object or chemical splashed in your eye
• You suddenly begin to see halos around lights
• You feel as if something is in your eye
• You have swelling in or around your eyes
• You're unable to open your eye or keep your eye open

Make a doctor's appointment

Occasional, brief periods of red eye are usually no cause for worry. If you think the redness is caused by a reaction to over-the-counter eyedrops, try a different brand or take a break from using them.

Contact your doctor for an appointment if you have red eye that doesn't clear up after several days, especially if you have a thick or nearly continuous pus or mucous discharge.

Contact your eye surgeon if you're experiencing eye redness with pain and you've had eye surgery in the past or if you've recently had eye surgery or an eye injection.