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Top 10 Causes of Red Eye

Why is your eye red?


Updated May 16, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

If you have a red eye, it is important to find out why. A red eye can be a sign of a medical emergency. A red eye is usually painless, and develops when blood vessels near the surface of the eye become enlarged and dilated.

While it is always best to seek the advice of your eye doctor, you may want to try a few red eye home remedies first.

1. Pink Eye

Top causes of Red eye
John Rensten Collection/Stone/Getty Images

Pink eye, or conjunctivitis, is an inflammation or infection of the clear, protective layer that coats the front part of the eye. Pink eye can be caused by allergies, bacteria, viruses, or toxic substances. Pink eye is very common but is usually not serious.

2. Blepharitis

Blepharitis causes inflammation of the eyelid and eyelashes and may be caused by poor eyelid hygiene. Oily eyelid glands, allergic reactions, bacterial infections, or lice on the eyelashes are also common causes of blepharitis. If you have blepharitis, you may notice a gritty or burning sensation in your eyes, excessive tearing, itching, red and swollen eyelids, dry eyes, or crusting of your eyelids. The condition is not contagious and usually does not cause permanent damage to your eyesight./p>

3. Uveitis

Uveitis, an inflammation of the eye's uvea, can cause redness, pain, blurry vision, floaters and light sensitivity. Symptoms of this condition can occur suddenly and get worse very quickly. Uveitis should be treated quickly because other complications, such as uveitic glaucoma or retinal and choriodal scarring, may occur if it lingers.

4. Dry Eye

Do your eyes feel dry? Tears protect our eyes by lubricating, nourishing and protecting the surface of the eye. When tears are lacking, our eyes can become dry and irritated. Chronic dryness can cause the surface of the eyes to become inflamed and blood vessels to dilate, causing increased redness. Ironically, dry eye can actually cause your eyes to produce an overabundance of tears, as your eyes often respond to discomfort by producing more tears.

5. Frequent Use of Eye Drops

Do you reach for eye drops when you wake up to red eyes? Surprisingly, frequent use of "get the red out" eye drops can actually make the eyes appear even more red. These whitening eye drops cause blood vessels in the eye to dilate, causing the eyes to appear even more bloodshot. Before instilling eye drops of any kins, it's a good idea to first consult with your eye doctor to identify the cause of your red eyes.

6. Contact Lens Wear

Wearing contact lenses can sometimes cause eye redness. In some people, simply having a contact lens in the eye is enough to make the eye red. If you experience discomfort while wearing contact lenses, you may want to try rewetting drops. These eye drops are formulated for contact lenses and can provide relief for dry eyes and discomfort associated with contact lens wear.

7. Injury

Redness sometimes occurs with an eye injury. Blood vessels in the eye enlarge and dilate to bring cells to heal and repair the injury.

8. Corneal Ulcer or Infection

If the eye's cornea becomes infected, nearby blood vessels become enlarged and swollen, as cells rush in to help fight the infection. These cells can cause visible redness.

9. Subconjunctival Hemorrhage

A bursted blood vessel often causes subconjunctival hemorrhage. When broken, these vessels bleed and spread out underneath the conjunctiva. Subconjunctival hemorrhage can be caused by sneezing, coughing, straining, vomiting, trauma, high blood pressure, diabetes and sometimes from certain blood disorders.

10. Acute Angle-Closure Glaucoma

Acute angle-closure glaucoma is a serious medical emergency that must be treated immediately. This serious type of glaucoma causes painful redness that usually occurs in one eye.

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