A subconjunctival hemorrhage occurs when a tiny blood vessel breaks just underneath the clear surface of your eye (conjunctiva). Your eye might feel sore, but there is usually no pain, blurry vision, or discharge. You may not even realize you have a subconjunctival hemorrhage until you look in the mirror and notice the white part of your eye is bright red.
A subconjunctival hemorrhage can be caused by a strong sneeze or cough can cause a blood vessel to break in the eye. This should resolve in 2 weeks, without treatment. Sometimes, I recommend cold packs to the affected eye, (15 minutes, 4 times a day), to reduce inflammation.