It is my understanding that prednisone causes increased eye pressure. It did in my case, anyway.
Also, the profound weakness I had caused narrow angle glaucoma, which I was already predisposed to because of the structure of my eyes. I did not know any of this till it happened. So with the increased pressures and closing of the angles, I had to have laser treatment to correct this. As soon as I went back for a recheck after laser, I started getting retinal tearing, which also had to be fixed with a laser.

Prednisone will also accelerate cataract forming.
I don't really know anything about the causes of macular degeneration.