Swelling in one eye and no swelling in the other eye may be caused by eye trauma, blepharitis, or blepharopharyngitis cysts. 1. Eye trauma: If the eye is injured in a fight or car accident, it can cause localized swelling around the eye. If only one eye is damaged, usually only one eye is swollen. 2. Blepharophalangeal cysts: Blepharophalangeal cysts are chronic inflammatory granulomas of the blepharophalangeal glands formed on the basis of obstruction of the blepharophalangeal gland’s drainage ducts and retention of secretions. The patient can palpate a hard mass on the eyelid without pain, and the skin on the surface is elevated, so the patient’s eyes appear to be swollen. 3. Blepharitis: Blepharitis is a suppurative inflammation of the eyelid glands. Under the stimulation of inflammation, the patient’s eyelids may appear red and swollen, or even abscess. It is recommended that patients with significant eye swelling seek medical attention to evaluate their condition and follow the doctor’s instructions for treatment.