can we do msc in economy after bachelor in operation theatre technology?
Nope! For most of the colleges, its required that you are from BA/BSc Economics or you have studied a pass course with economics as a subject of study. Also some institutes consider Mathematics and Statistics graduates to be eligible as well. But as you aren't from any of such fields then sorry to inform you, you aren't eligible for the MSc Economics Course.
If you want to have more information related to economics visit the link below:
https://www.careers360.com/courses/economics-course
I hope this helps.