When the eyes look straight ahead, the black eye is not in the center may be abnormal. If the black eye is inward, it may be caused by internal strabismus or also internal canthus, if the black eye is outward, it may be caused by external strabismus. 1. Internal strabismus: internal strabismus is generally related to eye regulation, heredity, refractive error and other factors, the patient mainly manifests that when one eye looks, the other eye deviates from the normal eye position, so the internal strabismus patient will have the symptom that the black eye is not in the center but a little bit inward when he/she looks straight ahead. 2. Inner canthus: Because the inner canthus covers part of the inner corner of the eye and the conjunctiva, the black eyeballs are not in the center and look a little inward. As some children grow up and their face develops, the medial canthus may shrink or disappear. 3. Esotropia: Esotropia may be related to fusion dysfunction, refractive error, motor nerve palsy, genetic factors, etc. It is most common in infants and young children with family genetic history. Children with exotropia have eyes that are tilted outward, so the black eye is not in the center. It is recommended that patients with abnormal eye position should seek prompt medical attention to evaluate their condition and follow the doctor’s instructions for treatment.