Nearsightedness Macular Degeneration

I had my eye exam with my cataract specialist the other day. I questioned her about this new injection for Dry MD. She told me in my case because mine was caused by my nearsightedness, the injections would not work for me., my question is what is the difference between the age related MD and nearsightedness MD. Btw, I got a good report. No changes since last year. I was so happy. A little disappointed about the injections though. I do worry if I will, eventually lose the sight in my right eye altogether. I see my regular eye Dr in August. Thank you for your input.