Red blood clots in the eye is a manifestation of subconjunctival hemorrhage, which is caused by the rupture of capillaries in the conjunctiva, and has various causes: first, the most common is hypertension and arteriosclerosis, due to the hardening of blood vessels, elasticity decreases, often spontaneous capillary rupture, and subconjunctival hemorrhage; second, eye trauma, blunt contusion of the eye can cause the rupture of capillaries in the conjunctiva, and subconjunctival hemorrhage; third, violent cough, vomiting, etc. Subconjunctival hemorrhage can also occur; fourth, blood diseases, thrombocytopenia or coagulation dysfunction can also occur subconjunctival hemorrhage. When subconjunctival hemorrhage occurs, you can take vitamin C orally to promote absorption, do not drink alcohol, do not exercise strenuously, do not take hot baths during this period, and generally absorb on your own within 7-12 days.