Subconjunctival hemorrhages are small accumulations of blood beneath the conjunctiva Overview of Conjunctival and Scleral Disorders The conjunctiva is the membrane that lines the eyelid and loops back to cover the sclera (the tough white fiber layer covering the eye), right up to the edge of the cornea (the clear layer in... read more (the membrane that lines the eyelid and covers the front of the eye). Sometimes the whole eye appears red and sometimes only a part appears red. The blood comes from small blood vessels on the surface of the eye, not from inside the eye. Because the blood does not involve the cornea (the clear layer in front of the iris and pupil) or the interior of the eye, vision is not affected.
Subconjunctival hemorrhages usually result from minor injury to the eye, straining, lifting, pushing, bending forward, vomiting, sneezing, coughing, or eye rubbing (gentle or vigorous). Rarely, they occur spontaneously. Subconjunctival hemorrhages may appear frightening but are almost always harmless.
Subconjunctival hemorrhages disappear on their own, usually within 2 weeks. No treatment is helpful or necessary. A subconjunctival hemorrhage often occurs together with a black eye Black Eye In the first 24 hours after a blunt eye injury, blood may leak into the skin of the eyelid and surrounding areas, causing swelling and a bruise (contusion), commonly called a black eye. (See... read more 
.
