The causes of redness and swelling of the upper eyelid may be blepharitis, orbital infection, and trauma. 1. Blepharitis, such as mydriasis, is a localized purulent inflammation of the eyelid caused by bacterial infection. It is characterized by localized redness, swelling and pain in the eyelid, and hard nodules are detected. Pus spots are visible after suppuration, and the pus ulcerates. 2. Orbital infection can develop from blepharitis, but eyelid inflammation is more serious, eyelid redness, swelling and pain, high tension, may be accompanied by conjunctival congestion and edema, and even cause vision loss. 3. Ocular trauma can also cause eyelid redness and swelling, which can be accompanied by subcutaneous or subconjunctival hemorrhage, open wound or conjunctival laceration. A clear history of head and face trauma can help identify this. Redness and swelling of the upper eyelid may also be caused by other reasons, it is recommended to consult a doctor as soon as possible when it can not be relieved, after clarifying the cause of the disease, follow the doctor’s instructions to standardize the treatment, so as to avoid delaying the condition and have adverse consequences.