(HealthDay News) -- Redness or blood in the eye could be caused by an inflamed or broken blood vessel -- also known as a subconjunctival hemorrhage. The eye can look extremely red from only a small amount of blood that has leaked and become trapped under the conjunctiva, or thin layer of tissue on your eye.
This condition usually is harmless -- although it may look bad -- and the blood normally will clear up on its own.
While anyone can have a subconjunctival hemorrhage, Fairview Health Services says people with high blood pressure may be more susceptible. Certain activities that may cause strain to the eye, such as rubbing the eye, sneezing, coughing, or lifting heavy objects, may also cause a blood vessel to break.
Redness should disappear within one to three weeks without treatment. A subconjunctival hemorrhage should not cause any impairment or change in your vision; if you do notice a change, see your doctor at once.