Swollen eyes are usually caused by allergies, infections and abnormalities in kidney function. 1. Allergy: the subcutaneous tissue of the eye is very loose, and the skin of the eye itself is very tender, which is prone to edema. Once an allergy occurs in the eye, it will lead to the collection of body fluids into the tissue space, thus forming edema. 2. Infection: eye infection is one of the most common causes of edema, common eye infectious diseases include conjunctivitis, keratitis, granuloma, acute cellulitis of the eyelids, dacryoadenitis and so on. 3. Abnormal kidney function: Once the kidney disease occurs, affecting the function of the kidney, it will lead to electrolyte metabolism disorders, which is also easy to cause ocular edema. Patients with swollen eyes should go to the hospital in time for examination, identify the causes, and carry out targeted treatment.