Red blood in the eyes can be seen in many eye diseases, the common ones include the following: First, conjunctival congestion caused by eye fatigue, which is usually not accompanied by increased eye secretions, but by a foreign body sensation or dryness and soreness of the eyes. Second, local inflammation, such as conjunctivitis, keratitis, such diseases will appear in addition to conjunctival congestion, but also accompanied by a large amount of purulent secretions. Thirdly, glaucoma, a disease caused by elevated intraocular pressure, is associated with mixed conjunctival congestion, and is accompanied by ocular distension, dizziness, headache, vision loss, and in severe cases, nausea and vomiting. Fourth, sterile inflammation in the eye, such as uveitis. The above diseases are treated in different ways, so if you have eye congestion, you must go to a regular hospital for a detailed examination to clarify the cause before giving symptomatic treatment.