Most of the blood under the eye is due to conjunctivitis, which causes the blood vessels under the eye to dilate and produce red blood. This condition of conjunctivitis is mostly due to eye fatigue after the expansion of blood vessels, and can be accompanied by eye soreness, pain, foreign body sensation and other symptoms appear, you can usually use appropriate anti-fatigue drops, such as nalmivir drops, etc., to improve eye symptoms blood vessels will gradually disappear. If not treated in time, eye congestion will increase, and the conjunctival surface of the eye will be distributed with a large number of red blood vessels resulting in vision loss.