A small blood vessel breaks in the white part of the eye and makes it bright red. This is also called a subconjunctival hemorrhage. There is usually a patch or line of redness on the white part of the eye. The redness can increase over 24 to 48 hours, especially if you are taking aspirin or blood thinners. Usually, it clears up by itself in a week or two, like a bruise on the skin.
A direct injury to the eye can cause bleeding in the white of the eye. It can also be caused by coughing, vomiting, sneezing, or a bowel movement. Being on blood thinners such as aspirin or warfarin may increase the risk. However, most of the time, there is no clear cause for it.
You will probably not know you have it unless you look in a mirror or someone tells you that your eye is red. Some people have a mild scratchy feeling in the eye. It should not affect your vision.
Your healthcare provider will look at your eye. Usually no tests are needed. If it happens to you a lot, a blood test may be done to check for a bleeding problem.
Usually, no treatment is needed. The blood becomes absorbed over time and the eye becomes clear again. The scratchy feeling can be treated with artificial tears (eyedrops).
In most cases, the redness in your eye goes away in 1 to 3 weeks. The affected part of the eye often turns yellow before it turns white again.