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
Systemic acyclovir in herpes zoster is useful: 
Select and explain. 
A. When staed immediately after the onset of rash, B. For post-herpetic neuralgia, C. For ocular lesions only, D. All of the above
A: When staed immediately after the onset of rash
Answer: A: When staed immediately after the onset of rash 
Explanation: Ans. When staed immediately after the onset of rash