zero Hi, no worries about your English, it's not my native language either.
They can be set at low brightness, but as being mentionned by Sunspark, it depends on the root cause of your problem. If your main issue is based on PWM, the effect is indeed quite strong at low brightness. I can see the PWM with my phone easily. For me, the main issue is somehow related to LEDs or light spectrum maybe, not to the software nor PWM. Halogen, and old school lightbulbs and lighting sources never caused me discomfort despite using dithering (for my computer) or PWM (for my halogen lightbulbs).
If your problem is truly brightness, then maybe you should try something like e-ink screens (with no lights) or RLCD monitors like SunVision or transflective like Eazeye, so you can choose your lighting source.