My thoughts for what they are worth. I'm 74, have had double cataract surgery and was legally blind w/o glasses before the surgery.
If you need more power to see better you need to have your eyes looked at, age will not change a scopes ability to transmit an image. It sounds more like you are compensating for loss of vision by upping the power of the scope instead of actually correcting your vision.
Having BDC reticle calibrated for the highest power on the scope isn't a problem. If the animal/target is far enough away to need to use the BDC the highest power should not be a problem.
Any time you are shooting larger game not off a rest, I find FOV will trump X's(power).
Keeping a scope on it's lowest power has the advantage of having the largest FOV for that quick close in shot. If the animal is out far enough that you need more X's to place your shot there is usually plenty of time to turn up the scope.
In the field I've never been under scoped but I have been over scoped.
My coyote and big game rifles wear glass fro 1-4x20mm to 2-12x42 with a majority of them 1.5-6x40+mm, note all have a large FOV on the bottom end.
My GS, PD and paper rifles have 4-16x40mm or 6.5-20x40mm,
Last edited by erich; 06/10/21.
