The size of the eyes may not always be the same at birth, if it is obvious that the size of the eyes is the same, it is ptosis, which refers to the partial or total drooping of the upper eyelid due to the incomplete function or loss of the levator and Muller smooth muscle, that is, the upper eyelid of one eye may cover a part of the cornea when looking in front of the other eye. Ptosis can be congenital or acquired. If one eye is large and the other small at birth, it is definitely congenital, mainly due to dysplasia of the nucleus accumbens or the levator ani muscle, which is either autosomal dominant or recessive, and congenital ptosis is usually bilateral but not necessarily symmetrical, and sometimes it can be unilateral. It is often accompanied by a dysfunctional upward turn of the eye. The skin of the eyelid of the ptotic eye is smooth and wrinkle-free. If the pupil is covered by the eyelid, the patient will contract the frontalis muscle to overcome the visual impairment, creating deeper horizontal skin wrinkles. Surgery is the main treatment for congenital ptosis. If the pupil is covered, surgery should be performed as soon as possible in order to avoid amblyopia, especially in monocular children, where oral medication is generally ineffective, and the surgery can be categorized as either levator palpebral muscle shortening or frontalis muscle suspension.