Many people may encounter such a situation, no painful edge without itching suddenly found the eye “white” at a large red, very frightening. Many people think that this is a “red eye” or “fundus bleeding”, but in fact, this is only a subconjunctival hemorrhage, which is not a serious disease in ophthalmology and is not contagious and will not cause blindness. The bulbar conjunctiva is a thin, almost transparent membrane that covers the surface of the eye like skin. In normal people, there are small, filiform blood vessels in the bulbar conjunctiva, which can only be found in healthy eyes by looking closely and can expand significantly when stimulated by pathological factors such as inflammation. In contrast, conjunctival hemorrhage is caused by the rupture of these small blood vessels, and because the blood is concentrated under the conjunctiva it appears to be a large red area, a phenomenon somewhat similar to the bruising under the skin after an injury. Depending on the amount of hemorrhage, the red area can vary in shape and size, or even cover the entire white eyeball if there is more. The hemorrhage is bright red or dark red when it first occurs, and turns yellowish over time, and is usually absorbed slowly over a few days to weeks without leaving a trace. Conjunctival hemorrhage is not caused by inflammation, trauma or surgery, but is more common in patients with hypertension, diabetes, blood disorders, etc. It is also associated with aging and hardening of blood vessels, especially in winter. Generally, cold compresses can be applied within 24 hours of conjunctival hemorrhage, and hot compresses can be applied after 3 days as appropriate, but there are patients in whom hot compresses can cause further hemorrhage, so I personally believe that it can be left to absorb on its own. To prevent conjunctival hemorrhage, we should pay attention to the following points: 1) Do not rub your eyes. 2) Avoid strenuous exercise. 3) Pay attention to forceful breath-holding actions, such as coughing, sneezing, vomiting, constipation, etc. 4) Abstain from alcohol (in some patients, alcohol causes bleeding). 5) Avoid emotional stress. 6) Pay attention to environments with large temperature differences. 7) Avoid prolonged head bowing or inversion. Bulbar conjunctival hemorrhage is only a symptom, but if it recurs, systemic systemic diseases should be examined.