If a baby’s eyes are large or small due to underdevelopment of the levator muscle or other causes, they can often return to normal within three months. If the eye size is caused by a congenital eye disease such as ptosis, it may be difficult for the eye size to return to normal on its own. Therefore, when an infant’s large or small eyes return to normal depends largely on the cause of the eye size. Some babies are born with underdeveloped muscles, such as the levator palpebralis muscle, which causes the baby to have large or small eyes. As the muscles gradually develop, the condition often returns on its own within three months and does not need to be treated. A small number of infants are born with congenital ptosis, which results in large or small eyes and is often difficult to recover from. It is usually necessary to choose the right time for ptosis surgery according to the severity of the symptoms to avoid abnormal visual development, e.g., mild ptosis, most of the time after the age of three years for surgical correction, large and small eyes can be returned to normal after the operation. It is recommended that infants seek medical attention in a timely manner to clarify the causes of large and small eyes and target treatment.