Ptosis is the downward displacement of the eyelids commonly due to age related weakness of the muscle that raises the eyelid. Genetic factors, trauma or injury, weakness after cataract surgery and neurological diseases can also result in ptosis. It differs from dermatochalasis in that it involves the muscle rather than the skin of the eyelid. With ptosis, the entire eyelid is lower than normal. Ptosis can affect peripheral vision, just as dermatochalasis does and in fact may be caused by dermatochalasis. If a significant impairment of vision is noted, most insurance companies will cover the cost of surgical ptosis repair. Untreated ptosis in young children can result in permanent loss of vision.