A subconjunctival hematoma is a visible collection of blood in the eye that results from a broken blood vessel. It specifically occurs in the subconjunctival space along the white of the eye, underneath the conjunctiva layer. Most subconjunctival hematomas are painless and do not disrupt vision. They usually go away in about two weeks without any special type of self-care or medical treatment. A hematoma that persists for longer than two weeks or recurs frequently may be a sign of an underlying health problem and should be evaluated by a doctor.
The blood vessels in the subconjunctival space are relatively delicate. They can break open and leak blood for a number of different reasons. A subconjunctival hematoma can arise after a forceful sneeze, a cough, a bout of vomiting, or a mild eye injury. Sometimes, simply rubbing an itchy eye is enough to break a blood vessel. Other potential causes and risk factors include high blood pressure, diabetes, anemia, and eye surgery.
Unless the hematoma is caused by an eye injury, it is likely to be entirely painless. A bright red spot appears on the white of the eye and spreads out as more blood is spilled. Since the blood vessel breakage is under the outer membrane of the eye, the pool of blood cannot be flushed out with water or dabbed with a tissue.
Most hematomas grow large in the first one or two days and slowly shrink away in one or two weeks. Like a skin bruise, a subconjunctival hematoma only lasts as long as it takes for underlying tissue to absorb all of the escaped blood. The spot typically gets lighter in color during the healing phase, changing from a bright red to a yellow-orange tint. After the two week mark, the white of the eye is usually back to normal.
It is important to visit an eye doctor if a subconjunctival hematoma is accompanied by vision disturbances, pain, or bleeding in other parts of the body. Medical care is also needed if hematomas appear in both eyes at once or if the red spot fails to fade away after a couple weeks. The ophthalmologist can examine the eye and run other tests as necessary to determine the underlying cause. A patient with pain may be prescribed soothing artificial tears or anti-inflammatory medications. Other issues such as high blood pressure and diabetes are treated appropriately with medications.