Red blood inside the eyes, may be related to eye fatigue, may also be due to dry eye, eye inflammation and other reasons. 1. Eye fatigue: If you look at cell phones, computers, tablets and other electronic products for a long time at close range, or regularly stay up too late, it is easy to cause eye fatigue, resulting in ciliary muscle over-adjustment, and the phenomenon of red blood inside the eyes will occur. 2. Dry eye: If you suffer from dry eye, it will lead to insufficient tear secretion or rapid evaporation of tears, resulting in the eyes can not be moisturized by tears, which may cause redness in the eyes, but also accompanied by itchy eyes, tearing and other symptoms. 3. Eye inflammation: common in conjunctivitis, keratitis, due to the conjunctiva or cornea parts of the inflammatory reaction, in the inflammatory products of the stimulating effect, can lead to red blood inside the eyes, but also with the eyes of foreign body sensation, eye pain and other symptoms. Red blood in the eyes, may also be caused by other reasons, if the symptoms continue to be unable to alleviate, or accompanied by other symptoms of discomfort, you should seek medical attention as soon as possible, clear diagnosis of the causative factors and then give targeted treatment.