Also known as red eye, a subconjunctival hemorrhage is a bright red patch appearing on the white of the eye. It is caused by bleeding from small blood vessels on the eye's surface that are easily ruptured or broken, causing blood to leak into the space between the conjunctiva and sclera (white of the eye). A subconjunctival hemorrhage does not impair your vision, cause pain or create discharge from the eye.
Although its appearance may be alarming, a subconjunctival hemorrhage is generally a harmless condition that does not require treatment. The redness will appear larger in the first 24 hours, but will gradually decrease once the blood is absorbed. Subconjunctival hemorrhages have been associated with high blood pressure, the use of blood thinners, straining, extreme sneezing or coughing, and eye injury.