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Eye redness - Overview

Alternative Names

Bloodshot eyes; Red eyes; Scleral injection; Conjunctival injection

Definition of Eye redness:

Red eyes are caused by enlarged, dilated blood vessels, leading to the appearance of redness on the surface of the eye.

Considerations:

There are many possible causes of a red eye or eyes. Some are cause for concern; some are medical emergencies. Others are of no consequence or concern at all. The degree of redness or appearance of blood usually does not correlate to how serious the situation is. It is generally more important whether you also have eye pain or impaired vision.

Common Causes:

Bloodshot eyes appear red because the vessels in the surface of the white portion of the eye (sclera) become enlarged and irritated. This may result from extremely dry air, sun exposure, dust, foreign body, an allergic reaction, infection, trauma, or other conditions.

One common cause of a red eye is straining or coughing. This can lead to a bright red, uniformly dense bloody area on the sclera. This is called a subconjunctival hemorrhage. Although this bloody area may appear alarming, it is a fairly common occurrence and of little significance. If you notice a bloody blotch in one eye that doesn't hurt, but just looks bad, don't worry. It generally clears up on its own within a week or two.

Eye infections or inflammation can occur in different locations. They cause redness as well as possible itching, discharge, pain, or vision problems:

  • Blepharitis -- inflammation of the eyelash follicles along the eyelid. It is caused by skin bacteria. Itching is common, and your eyelids may appear greasy or crusty.
  • Conjunctivitis -- inflammation or infection of the membrane that lines the eyelids and coats the surface of the eye (the conjunctiva). This condition is often referred to as "pink eye." It may be caused by a virus, bacteria, allergy, or irritation. If caused by an organism, this is highly contagious.
  • Corneal ulcers -- often caused by a bacterial or viral infection. (The cornea is the outer covering of the eye.)
  • Uveitis -- inflammation of the uvea, which includes the iris, ciliary body, and choroid. This is often related to an autoimmune disorder, infection, or exposure to toxins. Often, only the iris is inflamed, which is called iritis.

Other potential causes include:

  • Cold or allergies.
  • Foreign objects in the eye that cut or damage the eye. (See eye emergencies.)
  • Acute glaucoma -- a sudden increase in eye pressure that is extremely painful and causes serious visual disturbances. This is a medical emergency. Most times, glaucoma is chronic and gradual.
  • Corneal scratches caused by sand, dust, or overuse of contacts.
  • Bleeding problems (for example, from excess use of blood thinning drugs).
  • Reviewed last on: 11/10/2008
  • Linda Vorvick, MD, Family Physician, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

Greenberg MF. The red eye in childhood. Pediatr Clin North Am. 2003;50(1):105-124.

Wirbelauer C. Management of the red eye for the primary care. Am J Med. 2006;119:302-306.

Mueller JB, McStay CM. Ocular infection and inflammation. Emerg Med Clin North Am. 2008;26:57-72.

Rodriguez JO. Prevention and treatment of common eye injuries in sports. Am Fam Physician. 2003;67(7):1481-1488.

Rubenstein JB, Jick SL. Disorders of the conjunctiva and limbus. In: Yanoff M, Duker JS, Augsburger JJ, et al, eds. Ophthalmology. 2nd ed. Philadelphia, Pa: Mosby Elsevier; 2004:chap 55.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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