This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glaucoma, Subject name: Ophthalmology
Which one of the procedure involves using glaucoma drainage device 
Select and explain. 
A. Viscocanalostomy, B. Trabeculectomy, C. Deep sclerectomy, D. Seton operation
D: Seton operation
Answer: D: Seton operation 
Explanation: Glaucoma Drainage Devices :- * Plastic devices which allow aqeous outflow by creating an alternative communication between the anterior chamber & the Sub Tenon's space. * SETON OPERATION: surgery using glaucoma valve * Implants:- Molteno implants , Krupin Denver and Ahmed valve Indications: - * Neovacular glaucoma * Glaucoma with aniridia * Intractable glaucomas where trabeculectomy with anti- metabolite therapy fails. Ref:- A K Khurana Comprehensive Ophthalmology 7th edition; pg num:- 263