My eyes suddenly turned red. What happened?

Sudden redness of the eye, most common is subconjunctival hemorrhage. Subconjunctival hemorrhage can be caused by rupture or increased permeability of subconjunctival blood vessels. Strictly speaking, subconjunctival hemorrhage is a symptom, not a real disease. The exact cause can rarely be found. It is more common in one eye and can occur in any age group. Occasionally, there may be a history of severe cough, vomiting, etc. Other possible related medical history include trauma (eye injury or head crush injury), conjunctivitis, hypertension, arteriosclerosis, nephritis, hematological diseases (such as leukemia, hemophilia), certain infectious diseases (such as sepsis, typhoid fever, etc.). Please go to the hospital for specific treatment.