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This 2-year-old girl presented as shown.  Her parents say that the eyes have looked like this since birth. She is in good health otherwise demonstrating milestones of development as expected.  There is no family history of strabismus and the child's birth history and early development are unremarkable.  Visual acuity is approximately 20/400 in the right eye and 20/40 in the left.  Refractive error is +1.00 in each eye after cycloplegia and the media, and posterior aspect of the eyes including the optic nerves appear normal in both eyes.

1.	The most likely diagnosis in this case is:
	c -- This child appears with the right eye "down and out", the typical picture for a case of third nerve palsy.  The fact that this was present at birth makes the most likely diagnosis "congenital third nerve palsy".
2.	The muscles involved are:
	b -- The extraocular muscles innervated by the third nerve are four including the superior rectus, medial rectus, inferior rectus, and inferior oblique.  This leaves just two muscles functioning, the superior oblique innervated by the fourth nerve and the lateral rectus innervated by the sixth nerve.  In addition, the third nerve innervates the levator palpebri accounting for the ptosis of the right upper lid.
3.	The logical order of treatment would be:
	c -- The logical order of treatment is: treat the amblyopia, but carefully to avoid occlusion amblyopia as has occurred in some cases of congenital third nerve palsy but treated at a much younger age than this, then align the eyes to secure the best appearance.  Even with a successful result the eye will not move up very well.  This means that the ptosis should be treated last and is usually under corrected to avoid corneal exposure which could lead to drying producing discomfort and eventual corneal damage.