This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Ptosis with weakness of orbicularis- oculi is an early feature of- 
Select and explain. 
A. Fisher syndrome, B. Myasthenia gravis, C. Eaten lambert syndrome, D. Thyrotoxicosis
B: Myasthenia gravis
Answer: B: Myasthenia gravis 
Explanation: Myasthenia gravis is a major cause of ptosis & diplopia. The distribution of muscle weakness has a characteristic pattern. The cranial muscles particularly the lids and extraocular muscles are often involved early in the course of MG, and diplopia and ptosis are common initial complaints.