Corner pain is a symptom of a variety of conditions that can occur and requires a specialist to determine the specific cause. Corner pain is most commonly caused by an eye condition. For example, blepharitis, often called lacrimation, is a bacterial infection of the lid gland or lid margin follicle that causes redness, swelling, and pain in the eyelid; lacrimation, which occurs in the inner canthus (inner corner of the eye) and is acute in onset and causes redness, swelling, and pain in the inner canthus; blepharitis, especially canthal blepharitis, which often occurs in the outer canthus (outer corner of the eye) and causes congestion and swelling of the lid margin and skin in the outer canthus and may be erosive; and blepharodermatitis, which can be caused by chemical irritant dermatitis, contact dermatitis, herpes simplex, or herpes zoster viral dermatitis; in addition, it may be caused by eye trauma, dry eye, and eye strain. Corner pain can also be caused by the spread of inflammation near the corner of the eye, such as lacrimal gland inflammation, oral and maxillofacial and sinus inflammation causing involvement pain. Corner pain can also be caused by neuralgia such as trigeminal neuralgia from various causes. Therefore, if you have symptoms of pain in the corner of the eye, it is important to go to the hospital for further consultation to identify the cause of the pain in the corner of the eye for the next step of treatment.