This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Ophthalmology
A person has restricted eye movements in all directions, ptosis but no squint or diplopia. What is the diagnosis? 
Select and explain. 
A. Myasthenia, B. CPEO, C. Multiple cranial nerve palsy, D. Thyroid myopathy
B: CPEO
Answer: B: CPEO 
Explanation: Chronic progressive external ophthalmoplegia (CPEO)CPEO 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.