The best discussion I’ve found so far on how diopter correction for presbyopia interacts with the rest of your eye prescription and is adjusted for varying distances is in a blog post by one “Julie,” who lists no credentials beyond that she has worked “in an eye doctor’s office” (under the About section of her blog). How To Determine The Strength of Reading Glasses You Need - Contacts Advice
She presents a table on how the ADD diopter, which she indicates is for a focal length of 40 cm, should be adjusted for increasing distances:
So jlacroix of Foster Grant (quoted in my previous post) might be a little off in explaining how Foster Grant’s Multi Focus reading glasses work at increasing distance - another front desk person who doesn’t fully know what’s going on in the back?