If we need to type often and looking at the keyboard with differentials on, can it stagnate progress or worsen eyesight?
As long as your diffs are suited for the distance from the screen and you are taking breaks, you should be fine. Glancing at the keyboard shouldn’t effect anything. It is the prolonged point of focus that is an issue.
I agree here 100%.
The only time I have trouble with using differentials is when I’m working well inside my edge of blur long term, like hours. Then I get some ciliary spasm which takes a while to clear. I can get away with short glances at close distance even with my normalized without causing trouble.