Hi there, I have problems with vision a lot too. One thing I do in my daily meditation is raise my hand in front of my closed eyes once in a light trance. I begin to see my hands movements as I feel them at the same time. Then I put my hand down and try to see the exact thing with my physical hand resting on my lap. I find this increases inner vision drastically once in the astral state. Does that make any sense? lol
But also, once separated, I demand my vision in a forceful way and usually get it. Its like realizing its already there and just accepting it. Sometimes im afraid im opening my physical eyes when im in a very awake state of physical immobility. but it always ends up that my astral eyes open and I see the room around from a separated state.
Anyway, im no pro, but hope this helps.
Neat to meet!