Seeing a subconjunctival hemorrhage on the eye can be alarming, but it is quite common, it is usually harmless, and it will heal on its own. It will not affect your vision and usually will not cause pain.
The most common causes of this condition are sneezing, coughing, straining, or anything that raises the blood pressure in the veins, leading to a small rupture in a blood vessel or capillary. Other causes include rubbing the eye vigorously or trauma to the eye. Rare causes include blood clots or systemic blood disorders.
If the condition is recurrent or excessive, an ophthalmologist (Eye M.D.) may perform a medical workup, assess risk factors, and order laboratory studies.
Even though a subconjunctival hemorrhage can seem alarming, treatment is generally not necessary. The blood spot will slowly disappear on its own. If your eye is irritated, an ophthalmologist may recommend using over-the-counter artificial tears.
(c) 2007 The American Academy of Ophthalmology