This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epilepsy, Subject name: Pharmacology
In a child of infantile spasm and visual defect, which drug is not used even though it is highly effective? 
Select and explain. 
A. Lamotrigine, B. Topiramate, C. ACTH, D. Vigabatrin
D: Vigabatrin
Answer: D: Vigabatrin 
Explanation: Two types of drugs are used in infantile spasm:* ACTH (drug of choice)* Vigabatrin (drug of choice if infantile spasm with Tuberous sclerosis)Vigabatrin is a GABA transaminase inhibitor. Major side-effect is visual field defect. It is indicated in Refractory focal seizures with impaired awareness.So, because of this side-effect it can't be used if the child already has visual defect.