For aging eyes, be aware that they change with fatigue and often light level. I'm in the habit of resetting the diopter several times a day. It's amazing how different you'll find the settings late on a busy day of shooting compared to what was needed in the morning.
now that you remind me, I am aware that my near-sight changes depending on how much sleep I've had, etc. so thank you for the note.
regards,
Gregory