A sudden filling or partial filling of the whites of the eye with blood is referred to as a subconjunctival hemorrhage. It usually follows a trauma to the eye or even occurs after coughing or sneezing. The use of alcohol or certain drugs that thin the blood (anticoagulants) can contribute to a subconjunctival hemorrhage during the coughing or sneezing episodes.
A bright red blood patch covering a portion of the whites of the eye is the most obvious symptom. The red patch may become larger the day following the initial hemorrhage. The condition is usually painless. Mild discomfort may result from swelling on the outermost layer of the eye. Vision is usually not affected but your eye doctor will want to perform some simple tests to be certain.
The bright red blood spot will fade and disappear after a few weeks. To relieve any discomfort from swelling and to prevent additional bleeding, apply cold compresses several times a day for the first day or two. After a couple of days, you can apply warm compresses several times a day to aid in the healing process. A clean washcloth dipped in cold or warm water works but a hot water bottle works best.
Note: If vision begins to change, call your doctor immediately. Something else may have been affected.