about the prescription of Rescula

hi all.

my dad is in rentinitis pigmentosa for over 30 years and his vision drepress a lot recently, but we are in China. i found an article about the eye drop rescula, but unfortunatly it's not for sale in China, and all the online pharmacys need prescription from north America.

here's what i want to know:

1. is there any online hosipital to have a long-distance diagnose and prescription?

2. if we go to America to see a doctor, the priscription can only use once or for long term?

3. is there anyone in therapy is using this eyedrop and how about the effect?

thank you all..