This is a lot of good work!
Sorry to hear about the eye strain, as someone who works in IT, I also need to constantly take breaks, use eye refreshers and in general take care of myself. Can't say they ever hurt, but I do in ocasions get blurry eyesight out of having tired eyes.
It's incredibly annoying when it happens, not even eye refreshers will help at that point and I simply need to take a break until I feel well again. It's not frequent enough to be worriesome though.
Others already gave good tips, so the only thing I can add is, go to see an oculist if you haven't already. They can make tests and tailor a treatment specifically for your situation. Answer all your questions, and give you proper advice specifically for you for how long to use monitors for, if you might need specific glass types to help out, or something similar.
Bests of luck! you're doing good work here!