What is compensatory ptosis? Can anyone explain? I don't have it, but I'm researching it and what to know exactly what it is.
What is Compensatory Ptosis?
Doctor Answers (1)
Generally, we speak of compensatory eyelid retraction.
Ewald Hering was a 19th Century ophthalmologist who observed that paired eye muscles receive equal innervation (Hering's Law). This law helps us understand how eye muscles move the eyes. This law applies also to the paired muscles that raise the eyelids. The most common circumstance is when one eyelid is droopy or ptotic. When this occurs, there is generally a compensatory drive from the brain to stimulate the levator palpebrae superior muscle (the muscle responsible for raising the eyelid) to lift more. The ptotic eyelid is raised but the other eyelid without ptosis is also lifted higher than normal. The non-ptotic side is then said to be exhibiting compensatory eyelid retraction.
Compensatory ptosis is less common. It occurs when one eyelid is abnormally retracted. This can occur in certain circumstances. For example Graves' disease of the thyroid is associated with overactive thyroid and eye changes. This is the most common basis for eyelid retraction and yes only a single eyelid can be affected. When this occurs, in accordance to Hering's Law, the innervation to both of the upper eyelid muscles decrease. The normal eyelid falls more than the abnormally retracted eyelid and this is called compensatory ptosis. This can also be seen after eyelid surgery where one eyelid has been lifted more than is desirable.