Perhaps you should try some spelling variations:
original conference » retinal conference, regional conferences, optical conference
regional conference » regional convergence, national conference, regional differences
ida regional » ia regional, india regional, iaea regional

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( many original conference ) OR ( ida regional conference )).
• Adding a wildcard symbol may retrieve word variants: (( many original conference ) or ( ida regional conference ))*.