Sorry to hear about your eyesight problems. I don't believe anybody here can answer your questions.
We know nothing about the damage you have to your eyes and if it is irreversible or not. Even then, we are just Diabetics not specialists in Opthamology.
This sort of question is something you really have to ask the Consultant, even then I doubt you would get a definitive answer. Some things are just not able to be answered.
You mention your high Bg levels......you may possibly be able to slow the decline if you control those levels well, that's always assuming that the damage was due to the high Bg levels. I know from my own personal experience that my own eyesight improved dramatically after getting Bg levels down to more normal levels. That worked for me, but I have no idea if it would help you.
See the Consultant, grit your teeth.......ask the questions. Good luck.
Ken