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This 12-year-old boy has had a ptosis of the right upper lid as long as the family can remember. His vison is 20/20 in each eye. The parents reported that their son has assumed some unusual head positions. They are not consistent and no apparent head posture is noted at this examination. Refraction is +1.00 in each eye. The examinations of the anterior and posterior segments are normal. The boy denies diplopia and has no measurable fusion. His versions are as shown in the diagnostic positions. There is no change in the ptosis during chewing. His health is otherwise good and he has no difficulty swallowing.

1.	This ptoisis is most likely associated with the following diagnosis:
	e -- none of the above None of these diagnoses is likely to be correct. Not double elevator palsy because both eyes elevate. Not Marcus-Gunn because there is no movement of the lid with chewing. Not congenital ptosis because the right upper lid goes up fully in all directions of upgaze. Not myasthenia because the boy is healthy and has no trouble swallowing.
2.	The pictures of eye and lid movements in the diagnostic positions indicates the following:
	c -- the levator in the right eye appears to be functioning normally when the boy looks up The levator functions normally in up gaze. Steroids could be indicated if this were a case of ocular myasthenia. The right eye moves too well to support a diagnosis of third nerve palsy or to say there is a limitation of movement of the right eye.
3.	A possible diagnosis to consider in this case is:
	e -- all of the above All of the above can be possible. If this patient had a left fourth nerve palsy and habitually fixed with his left eye, this could cause the yoke of the left superior oblique to get more innervation and also its yoke, the right inferior oblique, would get more innervations pulling the eye down by Hering’s law and inhibiting the antagonist of the right inferior rectus, by Sherrington’s law. Whether or not this is the case, it should be considered.