Suddenly many red bloodshot eyes, there are several possibilities: 1. Inflammation caused by conjunctivitis, keratitis, iritis, sclerenitis can lead to eye congestion. The most common is acute conjunctivitis, which can manifest with red eyes, foreign body sensation, photophobia and tearing of the eyes, and a lot of eye secretions. Levofloxacin eye drops can be ordered 3-5 times a day and ganciclovir eye gel 4 times a day. The symptoms of dry eye include dilated conjunctival blood vessels, congestion, loss of luster, thickening and edema. 3. visual fatigue, refractive error causing visual fatigue, can also be manifested as eye congestion. 4. glaucoma, manifested as mixed conjunctival congestion, can have eye pain, sudden loss of vision, headache and other symptoms.