The redness of the patient’s eyes may be caused by acute bacterial conjunctivitis, acute glaucoma attack, iridocyclitis, visual fatigue and so on. 1. Acute bacterial conjunctivitis: under the stimulation of inflammation, patients with acute bacterial conjunctivitis may have conjunctival congestion, and may also have discomfort symptoms such as photophobia, tearing, and increased secretion. 2. Acute glaucoma attack: After the intraocular pressure rises in glaucoma patients, the patients may experience conjunctival congestion, eyeball swelling and pain, vision loss and other discomfort symptoms, which may also be accompanied by headache on the same side, and even nausea, vomiting and other systemic symptoms. 3. Iridocyclitis: under the stimulation of inflammation, patients with iridocyclitis may suffer from conjunctival congestion, eye pain, photophobia and other uncomfortable symptoms, as well as vision loss. 4. Visual fatigue: patients with visual fatigue due to overuse of eyes, staying up late, etc., patients may experience conjunctival congestion, photophobia, tearing, dryness and other discomforts. It is recommended that patients with obvious eye congestion should consult a doctor in time to assess their condition and follow the doctor’s instructions for treatment.