Swelling in one eye can be caused by a variety of reasons, such as eye allergies, eye infections, and autoimmune inflammation. Eye allergy is one of the most common causes of eye swelling, usually caused by allergic reactions of allergic patients after contact with cosmetics and skin care products, and can be treated with cold compresses to relieve eye discomfort. Eye tissue infection can also cause eye swelling, such as infectious conjunctivitis, blepharitis, blepharitis, etc., under the stimulation of inflammation, the patient can appear eye swelling, but also accompanied by conjunctival congestion, photophobia, increased secretion and other discomforts. Autoimmune inflammation is another common cause of ocular edema, such as chronic dacryoadenitis and inflammatory pseudotumor in the orbit. In addition, patients with renal failure and cardiac failure can also experience eye swelling, but it is usually seen in both eyes. Patients with swollen eyes are advised to seek prompt medical attention to evaluate their condition and follow the doctor’s instructions for treatment.