A broken blood vessel in the white of the eye, also called a subconjunctival hemorrhage, may look painful, though the bright red area does not cause damage to the eye. The condition does not typically require treatment and will heal on its own over a week or so. However, if the red area bulges or causes pain and changes to vision, you should contact an eye doctor. A broken blood vessel may happen spontaneously, without a known cause, but understanding some of the known reasons for the condition may help prevent broken blood vessels in the eye.
The blood vessels just under the covering of the white of the eye are small, and breaking one of these blood vessels does not require much effort. A common cause for a broken blood vessel in the eye is straining. This might involve lifting something heavy, vomiting, coughing or sneezing.
Rubbing the eye may also cause a blood vessel to break. The pressure does not have to be hard against the eye, and even a gentle rub may cause the vessel to break. Avoid rubbing the eyes and this may help prevent a broken blood vessel.
If a small particle or foreign object becomes lodged on the eye or under the eyelid, the object may scratch the white of the eye, causing a broken blood vessel. Playing baseball, or other sports where a ball or object may hit the eye, may also cause the condition. Wearing safety glasses in some situations may prevent injury to the eye.