Strabismus can be caused by a variety of reasons, such as congenital developmental abnormalities, tumors in the eye socket, thyroid-related eye diseases, trauma to the eye, and so on. 1. Congenital developmental abnormality: It is the most common cause of strabismus, which is usually caused by uncoordinated movement of extraocular muscles or abnormal adjustment ratio of the eyes. 2. Tumor in the orbit: it may infiltrate the surrounding tissues and affect the movement of extraocular muscles, thus forming strabismus. 3. Thyroid-related eye disease: it causes the extraocular muscles to become thicker and less elastic, and gradually lose their functions, and strabismus may also occur. 4. Trauma to the eye: there is a possibility of direct damage to the extraocular muscles, leading to strabismus symptoms. If you find strabismus in your eyes, you should consult a doctor as soon as possible and follow the doctor’s instructions for treatment and medication.