A swollen and painful upper eyelid in one eye is considered to be a bacterial infection of the lid gland, also known clinically as mydriasis and pinhole, which is often a purulent inflammation caused by the overgrowth of Staphylococcus aureus. It occurs in both children and adults and is characterized by redness and swelling of the eyelids, tenderness or pain on pressure, and pain when blinking. The treatment for mydriasis is topical anti-inflammatory medication, such as levofloxacin or tobramycin drops, which can be combined with tobramycin eye ointment or gatifloxacin eye ointment. If there is a significant increase in redness or pain, oral antibiotics, such as cephalosporin or amoxicillin, can also be used for systemic anti-inflammatory treatment, which will shorten the healing process of mydriasis and allow the redness and pain of mydriasis to heal more quickly.