I shoot lefty and I think I'm right eyed dominant. I always got around this problem by closing my right eye.  I gun-barrel the arrow, accuracy for me depends on aligning the run of the shaft to the target. I also double anchor, nose to the cock feather, thumb knuckle to the ear lobe.
I have developed a type of target panic where I can set my alignment to the left of the target, and have to kind of jab at the bull, swing at it and release.
For the heck of it I put on a set of safety glasses, blackened out the right lens. Now I'm aiming (aligning) with both eyes open although only using the left. Wow, what a difference, I can align right to the center of the bull, hold, and the clarity of the target is incredible!
I can't seem to do this without patching the right eye.
What's going on with me and anyone have any ideas?

Yes, I do know what is happening to you concerning your eyes. By completely blackening out one eye (closing it) you were creating a sympathy dialating effect in the open eye.

This does not happen when using your blinder and keeping both eyes open since light is still entering both eyes.  

Anther idea for a blinder is using a light opaque type patch and keeping both eyes open. Or you can use your safety glasses and just use a small piece of tape (just enough to block the target).

In time, you should be able to train the dominance of your eyes. At that point you will not need a blinder or close one eye.

Chuck,  It's always better in my opinion to shoot the side of eye dominance. BUT if you have been shooting this way for a while What you are discovering, I think, is that by closing your right eye, you are taking it out of the "brain input".  By blacking out the right lens of the glasses and keeping that eye open, you are forcing a left eye dominance signal to the brain.  This is one of the ways that a person can change eye dominance but it will take a while until you don't need the glasses anymore.

Well, you asked for ideas, there's mine.   :p

Great responses. thanks.
Is it possible to train my left eye to be dominant?
If I wear the patch, keep both eyes open, force the left to be dominate, will I eventually be able to loose the right eye patch?

You may want to ask an eye doctor about that but yes, I believe that you can train yourself to be left eye dominate.  What it really takes though could be better answered by a specialist IMO.

QuoteOriginally posted by chuck172:
Great responses. thanks.
Is it possible to train my left eye to be dominant?
If I wear the patch, keep both eyes open, force the left to be dominate, will I eventually be able to loose the right eye patch?

As far as aiming in shooting sports go, yes IMO.

In my experience with the student that I had we went from:

1. One eye closed
2. Black eye patch, eye closed.
3. Black eye patch, eye opened (both eyes opened from here on)
3. Holes in the black eye patch to let some light in.
4. An opaque patch.
5. A meshed patch.
6. Glasses with tape only large enough to cover target.
7. Nothing, both eyes open.

The whole thing took about a year. Of course this could differ widely. I have heard reports of as little as 3 months.

Pair of sun glasses with the aiming eye lens removed worked for me.