Dont use eye patches that block out the light into the no shootin eye, you will have sypathetic iris opening and depth of field issues with your shooting eye. If you are shooting with glasses just use some scotch tape to cover the target portion in the non shooting eye. You dont want the ambient edge light blocked out as it changes your iris size on both eyes., try a different patch further away(I use a white foam one attached to the rear sight that just covers downrange but still allows me to look down and spot with my scope) what ever works for you but dont close off light to that non shooting eye. It does make a difference.