Patients with one swollen eye may be caused by overwork, eye diseases, systemic diseases and other reasons. 1. Overwork: patients with sleep deprivation, overuse of eyes, visual fatigue, etc. may have swollen eyes, mostly in both eyes, and one eye may appear to be swollen and obvious. 2. Local eye diseases: conjunctivitis, blepharitis, keratitis or eye allergies, eyelid contact dermatitis, mosquito bites, eye trauma and other ocular diseases patients, after inflammation or traumatic injury stimulation, the patient may appear one eye swelling. 3. Systemic diseases: hypertension, kidney disease, heart failure can also lead to eye swelling, one eye can be swollen obviously. It is recommended that patients with obvious eye swelling should consult a doctor in time to evaluate their condition and follow the doctor’s instructions for treatment.