Eye redness refers to a red appearance of the normally white part of the eye. The eye looks red or bloodshot because blood vessels on the surface of the eye widen (dilate), bringing extra blood into the eye. Pink eye typically refers to eye redness caused by a viral infection.
Blood vessels can dilate as a result of
Infection
Allergy
Inflammation caused by something other than an infection
Elevated pressure inside the eye, typically caused by sudden, closed-angle glaucoma, in which fluid pressure increases in the front chamber of the eye
Several parts of the eye may be affected, most commonly the conjunctiva (the thin membrane that lines the eyelid and covers the front of the eye), but also the iris (the colored part of the eye), the sclera (the tough white fiber layer covering the eye), and the episclera (the connective tissue layer between the sclera and the conjunctiva).
An Inside Look at the Eye
Rarely is eye redness the only eye symptom. People may have tearing, itching, the feeling that a foreign object is in the eye (foreign body sensation), sensitivity to light, pain, or even changes in vision. Sometimes people have symptoms that affect other areas of the body, such as a runny nose or cough, or nausea and vomiting.
Causes of Eye Redness
Many disorders can cause eye redness. Some are emergencies, but others are mild and go away without treatment. The degree of redness does not indicate the seriousness of the disorder. The presence of eye pain or vision problems is more likely to suggest a serious cause.
The most common causes of eye redness are
Inflammation of the conjunctiva caused by an infection (infectious conjunctivitis, or pink eye)
Inflammation of the conjunctiva caused by an allergic reaction (allergic conjunctivitis)
Scratches of the cornea (the clear layer in front of the iris and pupil) and foreign objects in the eye are also common causes of eye redness. In these cases, however, the person is more likely to consider the problem to be an eye injury, eye pain, or both. Corneal scratches may be caused by contact lenses or by foreign objects or tiny particles trapped under the eyelid. Occasionally, very dry air can cause some eye redness and irritation.
Serious causes of eye redness are much less common. They include corneal ulcers, herpes simplex keratitis (herpes infection in the cornea), herpes zoster ophthalmicus (shingles in or around the eye), acute closed-angle glaucoma, anterior uveitis, and scleritis (a deep, painful inflammation of the sclera).
Some Causes and Features of Eye Redness
Cause | Common Features* | Diagnostic Approach |
|---|---|---|
Conjunctival disorders and episcleritis† | ||
Allergic or seasonal conjunctivitis (inflammation of the conjunctiva—the membrane that lines the eyelid and covers the front of the eye) | Affecting both eyes An itching or scratching sensation and tearing In people with known allergies or other features of allergies (such as a runny nose that recurs during certain seasons) | A doctor's examination |
Chemical (irritant) conjunctivitis | An itching or scratching sensation and tearing Exposure to potential irritants (such as dust, smoke, ammonia, or chlorine) | A doctor's examination |
Episcleritis (inflammation of the tissue between the sclera—the white of the eye—and the overlying conjunctiva) | Affecting only one eye A spot of redness on the white of the eye Mild irritation of the eye | A doctor's examination |
Infectious conjunctivitis (pink eye) | An itching or scratching sensation, tearing, and sensitivity to light Sometimes a discharge from the eye and eyelid swelling Sometimes swollen lymph nodes in front of the ears | A doctor's examination |
Subconjunctival hemorrhage (bleeding under the conjunctiva) | Affecting only one eye A red patch or large area of redness (that looks like blood or ketchup) No tearing, irritation, itching, change in vision, pain, or discharge from the eye Sometimes in people who have had an eye injury, sneezed violently, or tried to exhale without letting air escape, as may occur during a bowel movement or while lifting a heavy weight (called the Valsalva maneuver) | A doctor's examination |
Corneal disorders‡ | ||
Contact lens keratitis (inflammation of the cornea—the clear layer in front of the iris and pupil) | Eye ache, redness, tearing, and sensitivity to light In people who have worn their contact lenses for too long | A doctor's examination |
Corneal scratch (abrasion) or foreign object (body) | Symptoms that begin after an eye injury (which may not have been noticed in infants and young children) Pain when blinking and a foreign body sensation | A doctor's examination |
Sometimes a grayish patch on the cornea that later becomes an open, painful sore Sometimes in people who have had an eye injury or who slept with their contact lenses in | A doctor's examination Culture of a sample taken from the ulcer (done by an ophthalmologist) | |
Epidemic keratoconjunctivitis (pink eye—inflammation of the conjunctiva, the membrane that lines the eyelids and covers the front of the eye, and the cornea caused by an adenovirus) | Watery discharge Eyelid swelling, enlarged lymph nodes and bulging of conjunctiva Sometimes temporary loss of vision | A doctor's examination |
Herpes simplex keratitis (infection of the cornea caused by the herpes simplex virus) | Affecting only one eye Early: Blisters on the eyelid and/or crusting Late or recurring: Eye redness and tearing, eye pain, impaired vision, and sensitivity to light | A doctor's examination Sometimes, testing for the virus in scrapings obtained from the surface of the cornea or from blisters around the eye |
Herpes zoster ophthalmicus (shingles that affects the face and eye, caused by the varicella-zoster virus) | Affecting only one eye Early: A rash with fluid-filled blisters and/or crusting on one side of the face, around the eye, on the forehead, and/or on the tip of the nose, and sometimes pain Eye redness, tearing, and eyelid swelling Late: Eye redness, usually sensitivity to light, and usually severe pain | A doctor's examination Sometimes, testing for the virus in scrapings obtained from blisters around the eye |
Other disorders | ||
Severe eye ache and redness Headache, nausea, vomiting, and pain with exposure to light Disturbances in vision such as seeing halos around lights and/or decreased vision | Measurement of pressure inside the eye (tonometry) and examination of the eye's drainage channels with a special lens (gonioscopy), done by an ophthalmologist | |
Anterior uveitis (inflammation of the anterior chamber—the fluid-filled space between the iris and cornea) | Eye ache and sensitivity to light Eye redness (particularly around the cornea) Blurring or loss of vision Often in people who have an autoimmune disorder or who recently had an eye injury | A doctor's examination |
Scleritis (inflammation of the white of the eye, called the sclera) | Pain, often described as boring, and severe enough to wake someone from a sound sleep Sensitivity to light Tearing Red or violet patches on the white of the eye Often in people who have an autoimmune disorder | A doctor's examination Sometimes, ultrasound, or CT of the orbits Rarely, biopsy |
* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. † Conjunctival disorders usually cause itching or a scratchy sensation, tearing, widespread eye redness, and often sensitivity to light. They usually do not cause pain or changes in vision. ‡ Corneal disorders usually cause pain (particularly when the eyes are exposed to light), tearing, and sometimes impaired vision. | ||
Evaluation of Eye Redness
Not every case of eye redness requires evaluation by a doctor. The following information can help people decide when to see a doctor and to know what to expect during an evaluation. In most cases, people with eye redness can be evaluated by a general health care practitioner rather than an ophthalmologist (a medical doctor who specializes in the evaluation and treatment—surgical and nonsurgical—of eye disorders).
Warning signs
In people with eye redness, certain symptoms and characteristics are cause for concern. They include
Sudden, severe pain and vomiting
Rash on the face, particularly around the eyes or on the tip of the nose
Decreased sharpness of vision (visual acuity)
An open sore on the cornea
When to see a doctor
Deep eye pain should be distinguished from irritation. People who have warning signs, particularly deep pain or a change in vision, should see a doctor right away. If no warning signs are present, it is safe to wait a couple of days or so, but people may want to see a doctor sooner so that they can start treatment quickly.
What the doctor does
Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What they find during the history and physical examination often suggests a cause of eye redness and the tests that may need to be done (see table Some Causes and Features of Eye Redness).
Doctors ask
How long redness has been present
Whether redness has occurred before
Whether there is pain or itching
Whether there is discharge or the eyes are tearing
Whether there is a change in vision
Whether there has been an eye injury
Whether the person wears contact lenses and whether they have been overused
Whether the person has been exposed to substances (such as dust or eye drops) that could irritate the eyes
Whether there are other symptoms (such as headache, halos around lights, runny nose, cough, or sore throat)
Whether the person has allergies
Pain together with nausea or vomiting or halos around lights is a potentially serious combination of symptoms. These symptoms often occur in acute closed-angle glaucoma. Pain and sensitivity to light may indicate a disorder of the cornea, such as a scratch or foreign object. An absence of pain and sensitivity to light may indicate a disorder of the conjunctiva.
During the physical examination, doctors examine the head and neck for signs of disorders that may cause eye redness, such as runny nose and cough that may indicate an upper respiratory infection or allergy or a rash that may indicate shingles (herpes zoster infection).
The eye examination is the most important part of the physical examination. Doctors check the person's eye and the area around the eye for injuries or swelling. They check the person's vision (with glasses or contacts if the person wears them), pupil size and response to a light, and eye movement.
Doctors use a slit lampcorneal disorders. While the eye is anesthetized, pressure inside the eye (intraocular pressure) is often measured (called tonometry).
If pain develops in the affected eye (particularly if it is shut at this time) when a light is shined in the unaffected eye, the problem may be anterior uveitis or a corneal disorder. The use of an anesthetic makes the examination easier, and the person's response to the anesthetic may be a clue to the diagnosis. Anesthetic eye drops do not relieve pain that is caused by glaucoma, uveitis, or scleritis.
Testing
Testing is usually unnecessary.
If doctors suspect a viral infection (herpes simplex virus or varicella-zoster virus), they may take samples of discharge or blister fluid to send to the laboratory. The sample is placed in a culture medium (a substance that allows bacteria or viruses to grow). Samples for culture may also be taken when the person has a corneal ulcer so doctors can give antibiotics that are most likely to be effective. Gonioscopy (use of a special lens to examine the drainage channels in the eye) is done in people with glaucoma. Sometimes people with uveitis are tested for autoimmune disorders, especially if there is no obvious cause (such as an injury) for the uveitis.
People with scleritis are usually referred to an ophthalmologist, who often does additional tests.
Treatment of Eye Redness
The cause is treated. Eye redness itself does not require treatment. It usually clears up on its own as the cause resolves (for example, a few days for infectious conjunctivitis or a couple of weeks for subconjunctival hemorrhage). Cool washcloths or artificial tears can be applied if any itching is particularly bothersome. Eye drops that aim to eliminate redness (available over-the-counter) are not recommended.
Key Points
Usually, eye redness is caused by conjunctivitis.
Pain, a rash around the eye or nose, and changes in vision suggest a potentially serious cause.
