Painful redness and swelling in the corners of the eyes may be caused by other conditions such as dacryoadenitis, canthal blepharitis, boils, and acute blepharitis. 1. Dacryoadenitis: Dacryoadenitis may be caused by bacterial infection, viral infection, immune response, lymphoma and other factors. Patients may present with fever, yellow discharge, and pain or swelling over the outer orbital area. 2. Canthal blepharitis: Canthal blepharitis may be caused by infection of Bifidobacterium moaculatum, vitamin B2 deficiency and other factors, which may cause congestion, swelling, foreign body sensation, pain, itching and other manifestations of the outer canthus eyelid margin (corner of the eye). 3. Boils: Boils are mainly caused by Staphylococcus aureus infection. If boils appear at the corner of the eyes, there may be localized pain, swelling, fever and other manifestations. 4. Others: If there is pain, redness and swelling at the corner of the eye, acute blepharitis, herpes zoster or orbital cellulitis should be considered. It is recommended that patients with pain, redness and swelling at the corner of the eye should consult a doctor in time, who will choose the appropriate measures to treat the cause of the disease.