Both closed. Could explain my low success rate hunting last fall. Just joking, 1 eye opened. Wait, no, 1 eye closed. Hmmm, I can’t remember. Let me go out side and shoot a few and I’ll get back to you!
I am right handed but left eye dominant. I usually need to close my left eye just for a second to force my right to take over aiming. After that I’m both eyes open. Let me tell you, I used to have HORRIBLE problems aiming and setting up sights before I installed a peep. I never knew I was left eye dominant until I installed a peep. I had given up Archery for about 8 years and then decided to pick it up again. Glad I did!