I shoot up to about 25 yards with both eyes open, but due to blurring and some double vision, at about 30 yards I have to use my dominant right eye only.
Of course it is not an exact deal and depends on outside light, but when I'm having a little trouble with my pin I close my left eye.

It doesn't seem to affect my shooting (in fact I seem to shoot better with one eye closed, but I know its considered bad form from shotgun hunting).

Also, a "gummer" bowhunter told me that it was okay to do that and he had a buddy that had a flip down patch or something like that.

Of course I don't plan on making the 3-D circuit, just killin deer.

This is absolutely no help to you GMMAT.