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
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.