Cause |
Levator function |
Eyelid crease margin |
|
Other clinical features |
Congenital abnormality of the levator muscle* |
Reduced |
Crease often absent |
Often unilateral |
Many patients also have amblyopia, strabismus |
Aponeurotic ptosis |
Normal |
Often increased |
Uni- or bilateral |
Isolated finding of ptosis |
Cranial nerve 3 palsy |
Reduced |
Normal |
Usually unilateral |
Impaired extraocular movement in ipsilateral eye. If ipsilateral pupil dilated, urgent evaluation for aneurysm is required. |
Horner's syndrome |
Normal |
Normal |
Usually unilateral |
Ipsilateral miotic pupil |
Myasthenia |
Reduced |
Normal |
Uni- or bilateral |
Variable and fatigable. Diplopia and extraocular movement abnormalities often present. |
Muscle disease |
Reduced |
Normal |
Usually bilateral |
Orbicularis oculi, other extraocular or bulbar muscles may be affected |