Sudden swelling of the eyes may be caused by physiological factors such as poor rest, drinking water before going to bed, or pathological factors such as trauma, localized eye infections and contact dermatitis. 1. Physiological factors: poor rest, visual fatigue, sleeping with the head too low, drinking too much water before going to bed and other reasons may lead to sudden localized swelling of the eyes. 2. Pathological factors: (1) When the eyes are traumatized, it can lead to localized tissue edema of the eyes, which can be manifested as swollen eyes. (2)When the eye localization is infected by bacteria, fungus, virus and other infections and produces inflammatory reaction, redness, swelling, heat, pain and other manifestations of the eyes may occur, and the eyes may appear to swell up suddenly. (3) Poor quality cosmetics, topical use of antibiotics, eyeglass frames and other allergens can lead to contact dermatitis of the eyelid skin, the patient may have symptoms such as itching, burning sensation, and may also have sudden swelling of the eyelid redness. It is recommended that patients exclude physiological factors and then go to the hospital for a detailed examination to clarify the cause of the disease and follow the doctor’s instructions for treatment.