I am 47 years old and my vision sucks. It is no harder painting 3mm figs than it is, say, painting belts on 28 mm figs. Like everything in minis, it is a question of tecnique and not one of eagle eye sight and rock steady hands. Paint for effect, not detail. That is the key.
Firstly, congratulations on your age. If I can remember that far back, 47 was a good age to be.
You might find that you are preaching to the converted with regards to some of the people responding to this thread. I find painting small figures very much easier than large figures, so I concur. No experience of 3mm figures but with 6mm I find the basing sometimes more important than the fine details of painting. For instance, I re-based my 6mm Polybian Roman hastati and princeps on 40mm by 20mm bases, with 2 ranks of 4 hastati on the right at the front of the base. On the left I put 2 ranks of 4 princeps to the back of the base. Even people with worse vision than myself can see what they are at more than playing distance.
Not a very good picture, but perhaps you can see what I am getting at?
O8’s 3mm figures are about 200 percent more detailed and recognizeable than Irregular’s 2mm figs.
Somehow, I find that easy to believe.