<prompt> A person has restricted eye movements in all directions, ptosis but no squint or diplopia. What is the diagnosis?MyastheniaCPEOMultiple cranial nerve palsyThyroid myopathy  <response>: Chronic progressive external ophthalmoplegia CPEOCPEO is a mitochondriopathy. There is slowly progressive weakness of all the ocular muscles with a variable degree of motility disorders and corresponding double vision, and subsequently there is also involvement of the limb muscles. 