Sometimes small blood vessels in the whites of the eyes break and cause a red spot or speck. This is called a subconjunctival hemorrhage. The blood vessels may break because of sneezing, coughing, vomiting, straining, or bending over, but sometimes there is no clear cause. The blood may look alarming, especially if the spot is large. It is usually not a cause for concern and will clear up in 2 to 3 weeks. Subconjunctival hemorrhage is usually not a serious problem if your vision is normal, there is no eye pain, and the bleeding does not cover a large portion of the white of the eye and does not spread into the colored part of the eye (iris).
Bleeding that occurs between the colored part of the eye (iris) and the cornea is called a hyphema. This is more serious than bleeding that occurs in the white of the eye. You may have mild pain or no pain at all. After an eye injury, blood usually appears immediately. But if the injury is mild, blood may not appear until up to 5 days later. You may also have vision changes. A hyphema may be a more serious problem for a person who has sickle cell disease. If you have a hyphema, see an eye specialist (ophthalmologist).