In normal people, the eyes are not perfectly symmetrical, and there is no problem if the upper lid margin does not cover more than 2mm of the cornea when the eyes are level. However, this is not the case in some children, who tend to have an upper lid margin that covers more than 1/5 of the cornea when they look forward, which is called ptosis. There are two types of ptosis: congenital and acquired ptosis. As the name implies, congenital ptosis is an autosomal dominant or recessive disorder that occurs at birth and is mainly due to hypoplasia of the nucleus accumbens or hypoplasia of the levator aponeurosis. Acquired ptosis is a condition that occurs after birth and has many causes, such as ophthalmoplegia, levator muscle injury, sympathetic nerve disorders, myasthenia gravis, and mechanical dysmotility, such as inflammation or tumors of the eyelid. Mild ptosis only affects appearance, while severe ptosis can impair visual function. The child often tilts his or her head back to see clearly and uses the frontalis muscles in an attempt to raise the upper lid, resulting in a lot of wrinkles on the forehead, known as “head lines”. If ptosis occurs in young children and is not corrected in time, it can also cause amblyopia. Acquired ptosis can be associated with other symptoms, such as damage to the nerve of the eye, which can be accompanied by paralysis of other extraocular muscles and diplopia, or myasthenia gravis, which can be mild in the morning and heavy at night, and can be relieved by intramuscular injection of neostigmine. How is ptosis treated? Congenital ptosis is treated with surgery. In cases where the pupil is obscured, surgery is required to avoid amblyopia. Ptosis can be treated with a shortening of the levator muscle, a silicone suspension of the frontalis muscle, or a frontalis flap suspension, which are more effective. In acquired ptosis, the first step is to treat the cause of the problem, which is neurological or other ocular or systemic diseases. Surgery may be considered after six months or more of ineffective treatment. Patients with severe muscle weakness should take oral prednisone and pyridostigmine, and some patients with thymic hypertrophy will require surgical removal of the thymus gland.