A sudden red blood clot in the white of the eye is usually caused by a subconjunctival hemorrhage, which usually does not require special treatment and can absorb on its own in 1-2 weeks without leaving traces. Some clinical aids can be used to shorten the disease cycle as appropriate, such as applying local cold compresses to promote vasoconstriction in the early stages of bleeding and hot compresses 2 days later, while taking care not to rub the eye to avoid aggravating the bleeding. In addition to symptomatic treatment such as cold compresses and hot compresses, attention should be paid to finding the cause of the bleeding and treating it accordingly. Clinical reasons that may cause a sudden red blood clot in the white of the eye may include the following: 1. Intense coughing and vomiting: Intense and frequent coughing, vomiting, and sneezing can lead to rupture of small blood vessels under the conjunctiva. The cause of coughing and vomiting needs to be clarified and anti-cough and anti-vomiting treatment should be given; 2. Trauma: such as eye trauma or head crush injury, active treatment for trauma is needed to relieve and improve the symptoms of a sudden red blood clot in the white of the eye; 3. Conjunctival inflammation: for inflammation, antiviral eye drops can be given for viral conjunctivitis, commonly used drugs include interferon eye drops, acyclovir eye drops, etc. Bacterial conjunctivitis can be treated with eye drops such as levofloxacin drops; 4. Other: for example, constipation, hypertension, arteriosclerosis, nephritis, blood system diseases such as leukemia, hemophilia, infectious diseases such as sepsis, typhoid fever, etc. can lead to the sudden appearance of a red blood clot in the white of the eye. Patients are advised to go to the hospital in a timely manner and under the guidance of the doctor to conduct routine blood tests, ultrasound and other examinations to clarify the diagnosis and then treat the cause.