Ptosis occurs when the upper eyelid droops to an abnormal level and covers part of the eye. It can have many causes including age, injury or nerve malfunction. It can also occur at birth.
Age is the most common cause of ptosis. The muscles that elevate the eyelid stretch and become thinned, resulting in a loss of muscle tone and the inability to hold the upper lid in the proper position above the eye.
Injury is another common cause of ptosis. Trauma to the eye, such as during an automobile accident, can damage the delicate structures around and in the eye.
Sometimes ptosis can be noticed at birth. In these cases it is due to an abnormality in the development of the muscles that elevate the upper lid. Three-quarters of the time it affects only one eye.
Ptosis can also be caused by a malfunction of the nerves which control and activate the eyelid muscles. These cases are rare and proper diagnosis is important in order to avoid unnecessary surgery. When a neurological disorder is present, symptoms typically include visual complaints independent of the droopy eyelid. Difficulty reading and driving are common complaints. Raising the entire brow with the muscles of the forehead and scalp may cause headaches and eyestrain as well. In newborns, this problem must be addressed and treated properly to insure normal maturation of the visual system and the avoidance of amblyopia (lazy eye).
The most common treatment for ptosis is surgical, and there are a number of possible approaches. The goal is to tighten the muscles so that the lid is elevated to match the lid on the other side, but with a minimum of scars and side effects. One possible complication is that the muscles can be over tightened. This results in the inability to close the eye completely after surgery. Such a situation creates a dry eye condition that may be difficult to manage.
In the age-related form, both eyelids may be drooping, but only one is low enough to require surgery. Almost invariably in these cases, the unoperated eyelid will appear lower after a successful repair of the first eye. The second eye also may eventually require surgery.