You should look for a monitor that doesn't have LED PWM Dimming or is Flicker-Free. But that's just the starting point. You strain your eyes when you focus on small things so you should buy something that is big and has high resolution. Then adjust the scaling until you're comfortable reading. Also, don't maximize the your monitor's brightness. Instead, find the medium between a dark room and a bright room since it's better for your eyes.
I've heard about BenQ too and Asus has eye care monitors as well.