(It's not actually specific to eyes barring one small bit that can be extrapolated to general use.)
The most amazing thing being that it's 20 minutes without paint or a brush.
Saw a post on Reddit about a book by this fellow, and after looking it up, I'd replied to the thread saying it looked interesting but I'd never heard of the guy. Got given a link to this in reply, saying it showed his teaching style. Very worthwhile watch, for me at least.