I struggled, but learned to shoot with both eyes open becausewas having a similar problem. I got a new pair of bifocals this year which made it very difficult to focus on the target and my pins with one eye. With only one eye, either the target or my pin was blurry unless I moved my head up & down to find that focus point.It took me about a month to train my brain to keep both eyes open when I aim. Another big advantage is being able to see your arrow. It isa tough habbit to break. I only hope when it comes time to draw on a deer, my brain will remember to open that left eye!
GOOD LUCK!