The sudden appearance of congestion in the eyes of patients is usually due to conjunctivitis, eye allergies, eye trauma, acute attack of glaucoma and other reasons. 1. Conjunctivitis: patients with poor eye hygiene habits, often rubbing the eyes with their hands, it is easy to cause conjunctival tissue infection, which can cause eye congestion, you can order ofloxacin eye drops treatment. 2. Eye allergy: allergic patients with allergens, such as pollen, willow, etc., easy to induce an allergic reaction, resulting in patients with conjunctival congestion, itching and other uncomfortable symptoms, patients can follow the doctor’s instructions to use anti-allergy drugs, such as naphthylamine eye drops. 3. Eye trauma: eye trauma patients because of mechanical stimulation of eye tissues, may suddenly appear conjunctival congestion, which is manifested as red eyes. 4. Glaucoma: After the acute attack of glaucoma, because of the rapid increase in intraocular pressure, the conjunctival tissue reactive congestion and even edema, but also with photophobia, eye swelling and pain and other uncomfortable symptoms. It is recommended that patients with sudden bloodshot eyes and other discomforts consult a doctor to evaluate their condition and follow the doctor’s instructions for treatment.