My eyes are bad too but I learned guitar repair before the internet introduced numbers to guitar setup. Basically all you need to do is press each string down to the fret and feel how far it goes. Lower it until it seems about right and make sure the string rings clear at every fret and doesn't feel too high. Once all are set you can use the same method to make sure none are much higher or lower than adjacent strings. Even using radius gauges for action adjustment is IMO all about retailers selling products to an unsuspecting public of hobby guitar techs. The radius of the strings should not match the radius of the fingerboard. Because 1) the low strings need to be higher to allow for their larger excursion, and 2) the top of the strings will have a different radius than the bottom, even if the bottom matches the board. The radius of the top of the strings should be a good deal flatter than the board radius! Setting the action with the strings in the same numerical radius as the board will give poor action, either too low on the wound strings, or too high on the D and G. I would agree that having some numbers that are typical ballpark action heights for a specific guitar can help hobby techs to be sure they are getting the expected results, but using the numbers on every string during setup is IMO harmful to both the learning process and the end result.