The following are used for treatment of postoperative nausea and vomiting following squint surgery in children except:

Ketamine is not used for treatment of postoperative nausea and vomiting. In fact ketamine use is itself associated with nausea and vomiting and requires prophylaxis. Ref: Lee's Synopsis of Anaesthesia, 12th Edition, Page 192; Textbook of Anaesthesia By Aitkinhead, 4th Edition, Pages 176, 244-49