Re: eye glasses, POI change ?
As a former optician, and person with awful vision, I can add to this conversation!
I have RX shooting glasses made out of a material called Trivex. Trivex is like polycarbonate but much nicer. It is highly recommended for shooting glasses. You can get it tinted if you desire. My shooting glasses have a pinkish tone to help me see orange clay pigeons (I am also red-green color deficient).
If you are getting shooting glasses made, and most often shoot rifles, or shotguns where your aim pose is a certain position. I.e. cheek weld.
You will normally be looking through a certain part of the lens. Go to your rifle/shotgun, put on your glasses, and take a wet-erase marker, put a dot right where you look through. So the dot is right in the middle of the spot you look through when looking down the barrel. If they cut the optical center at this vertical level, it will increase the optical clarity for your shooting position.
IT IS PROBABLY NOT IN THE CENTER OF THE LENS!
Take these lenses to your optician, marked this way, and have them put the optical center at that point. Usually, the optical center is lined up at the center of the frame, unless you have progressives.
It is very easy for them to measure this spot, vertically it is called a seg-height. Horizontally, they would probably still use your normal pupillary distance.
Note: people with spherical prescriptions will not see much difference using this process. People with astigmatism WILL see an improvement, based on how much astigmatism you have.