It can help to cover one eye with a patch, since it improves vision in the other. In the days of pirates they found a patch help see better at night. "Over time, swashbucklers who often found themselves embroiled in combat had learned how to adapt. Of course, the only way to move stealthily through the dark of night was to utilize your eyes to the fullest. By wearing a patch over one eye, pirates could “trick” their vision into adjusting to darkness more quickly".
Maybe that is why aiming with your dominant eye is important. "Your dominant eye is the one that provides slightly more input to the visual cortex of your brain and relays information more accurately, such as the location of objects. Research shows that eye dominance and handedness are associated, though not directly related".