The eye is swollen for no reason, and it hurts. In ophthalmology, blepharitis, intraocular foreign bodies, localized inflammation of the eye and other eye diseases are the most common causes. 1. Blepharitis: a suppurative inflammation caused by bacterial infection of the glands of the eyelids, manifested by redness, swelling and pain of the eyelids. 2. Foreign bodies in the eye: foreign bodies entering the eye can rub the surface of the eye, resulting in corresponding damage to the corneal epithelium or conjunctiva, which is mostly characterized by redness and swelling in the eye, accompanied by pain such as a foreign body sensation. 3. Localized inflammation of the eye: Inflammation of the corneal conjunctiva due to bacterial, viral and other pathogenic infections or autoimmune inflammation, which may be manifested as redness, swelling, pain and other discomforts of the eye. The eyes are swollen for no reason, but also pain, it is recommended that patients go to the hospital in time for a detailed examination, to clarify the cause of the disease, and follow the doctor’s instructions for treatment.