Definition of red eye
Red eye is a common problem that can affect one or both eyes. The redness associated with red eye comes from expanded blood vessels on the surface of your eye due to inflammation, usually from some form of irritation or infection.
Most often the inflammation that causes red eye occurs in the membrane covering the white of your eye and lining your eyelid. This membrane is called the conjunctiva (kun-JUNK-tih-vuh); inflammation of the conjunctiva is called conjunctivitis (kun-junk-tih-VY-tis).
Causes of red eye
- Allergic conjunctivitis
- Bacterial conjunctivitis
- Blepharitis (inflammation that affects your eyelids)
- Corneal abrasion (rubbing off of the very top layers of the cornea, the transparent cover of your eye)
- Corneal herpetic infections (herpes)
- Corneal ulcers
- Dry eyes
- Ectropion (condition in which your eyelid turns out)
- Entropion (condition in which your eyelid turns in)
- Episcleritis (inflammation of the membrane covering the white part of the eye)
- Foreign object in eye
- Hay fever
- Iritis (inflammation of the colored part of the eye)
- Keratitis (inflammation of the cornea)
- Orbital cellulitis (severe infection of tissues around the eye)
- Scleritis (inflammation of the white part of the eye)
- Sty (a red, painful lump near the edge of your eyelid)
- Subconjunctival hemorrhage
- Uveitis (inflammation of the middle layer of the eye)
- Viral conjunctivitis
“Pink eye” is a term commonly used to describe red eye and refers to both viral and bacterial infections of the conjunctiva (conjunctivitis). It can also have other causes, such as allergy.
Pink eye caused by a virus may involve clear discharge or some amount of pus and mucous discharge.
Pink eye caused by bacteria is more common in children than adults and may involve a more continuous and thicker discharge of pus and mucus.
- Pink eye (conjunctivitis)
When to see a doctor
Occasional, brief periods of red eye are usually no cause for worry. But persistent red eye, especially when accompanied by eye pain or vision changes, can signal a more serious problem.
Seek immediate medical attention if red eye is accompanied by:
- Vision loss
- Severe headache, eye pain, nausea or unusual sensitivity to bright light
- Inability to open your eye or keep your eye open
- A sensation that there’s something in your eye
For persistent 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 doctor for an appointment.