In order to be an Opthalmologist and an legal practitioner one need to pass MBBS and then followed by a MD/MS in Opthalmology. With only Diploma in Opthalmology you can't open your clinic and be a physician.

To know more about Opthalmology visit the link below:

https://www.careers360.com/courses/ophthalmology-course

I hope this answer helps. All the very best for your future endeavors!