I am very sorry to say but to pursue the diploma course inn the field of Optician technician field the basic eligibility criteria is that you must have passed your 10+2 from science field from a recognized board or university with Physics Chemistry and Maths/Biology as your main subjects. And since you have passed your 12th from Arts field, it looks difficult for you to get into the OT course.

Refer to the site below for more details..

https://www.careers360.com/careers/operation-theatre-technician

Best wishes. Thankyou.