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
Down beat nystagmus is seen in? 
Select and explain. 
A. Arnold chiari malformation, B. Brain stem damage, C. Pontine hemorrhage, D. Labyrinthine damage
A: Arnold chiari malformation
Answer: A: Arnold chiari malformation 
Explanation: Ans. is 'a' i.e., Arnold chiari malformation Down-beat nystagmus are seen in cerebellar lesion and Arnold-chiary malformation