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Red Eyes

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.

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:

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