>> A long time ago (in the 1980’s) there was a huge amount of work done
about font type and size used on screens and print outs. We found, to our
chagrin, that cool small fonts were the bane of most of the ‘older’
folks (that is to say anyone with bifocals).
This isn't an answer to your question, but just an added comment. Sorry.
About 5 years ago I read a study on font sizes (can't remember who did it),
but they found that designers shouldn't use small fonts for 20 somethings
either, because most of the time if they are sitting in front of a monitor
at a desk they are tipping their chairs back on the back legs, so are
further away from the monitor and can't read it either.