(HealthDay News) -- Eye redness occurs when blood vessels on the surface of the eye become dilated.
Here are some common causes of red eyes, courtesy of the U.S. National Library of Medicine:
- Straining the eyes.
- Persistent or severe coughing.
- An eye infection.
- A cold or allergy.
- Damage to the eye.
- Acute glaucoma.
- Scratches on the cornea, commonly caused by wearing contact lenses too long, or sand or dust in the eyes.
- Bleeding problems, often caused by taking blood-thinning drugs.