Does the use of marijuana really help those with certain medical conditions such as HIV/AIDS, Hepatitis C, MS, Cancer or Glaucoma?

I’m asking for my father who is just starting to get glaucoma, though eventually I may have to get it myself (hopefully not). He has had back surgery (fused) and is on medications (which either string him out or put him to sleep).
Now I will likely get glaucoma myself here in a few years, I already have lost one eye due to an accident, and don’t like the thought of losing anymore vision. I have been on all sorts of medications myself, such as vicodin and many forms of oxycontin for a benign tumor that was in my leg (they cut out a piece of bone) and i hate those damn pills, make me feel like crap. What are the steps to get a medical marijuana card in Oregon? Would we have to go to Portland? Thnx.