There are many reasons for the redness and congestion on one side of the white eyeball, which may include infection, allergy, increased intraocular pressure or external stimuli. 1. Infection: Bacterial and viral infections are common in clinical practice. Infections can lead to symptoms such as conjunctival congestion, tearing, and excessive secretion, which are usually seen in conjunctivitis, keratitis, uveitis and other diseases, and patients can show congestion and redness on one side of the white eyeball. 2. Allergy: If contact with some kind of allergic substances, allergic conjunctivitis may be induced, resulting in the patient’s white eyeball side of the congestion and redness, in addition to the performance of conjunctival edema. 3. Increase in intraocular pressure: common in glaucoma patients, when the intraocular pressure suddenly increases, atrial fluid circulation can be impaired, resulting in redness and congestion on one side of the white eyeball. 4. External stimuli: mainly related to physical and chemical stimuli such as oil smoke, dust, or sudden external injuries, which may lead to redness and congestion on one side of the white eyeball. If the white eyeball is red and congested, it is recommended to go to the hospital to find an ophthalmologist to make a relevant examination, a clear diagnosis, and symptomatic treatment.