Use red dot issue solved. Even works if dot is covered from the front as long as target focused.

Doesn't solve it for me.  I can't zero an M4 w/ both eyes open.

Zeroing and actual use are two different beasts. The goal in zeroing is having the most precise and accurate group. Actual use is acceptable sight and shot. You shouldn’t be looking through a red dot when shooting normally and not for precision.

Think you need to splain yourself.  That's a different premise than 87% of red dot users follow.

The purpose of a red dot is to be target focused. In order to be able to use a red dot well the first thing you need to have is solid presentation. Work backwards on presentation. Meaning start with the gun on target, dot in middle. Next go to compressed ready by bending elbows only, make sure you do not move wrist or open grip. Now go back to full extension and your dot should be on. Repeat and you will soon build muscle memory.

Once you are no longer searching for dot and are consistently acquiring dot upon presentation (you should know as soon as you grip from a holster if it’s a good presentation) then tape a piece of masking tape or painters tap on the front of the dot covering the window. Now present to target. If all you see is the tape, then you are not target focused. Keep focus on target and if you see the red dot super impose on the target without changing vision focus, then you are doing it right.

I have double vision, both eyes open doesn't work for me.

That's a lot more work than just closing one eye.

Red dot helped for me.

That "work" will make you a far better pistol shot, red dot or not.

Not that big a deal, really. But the benefits are many.

Angry pandas advice is spot on.

It sounds like more work than it is. Once you do it a bit it’s very natural.