Iris is an app that lowers the blue light that your screen emits, removes PWM flicker and dims it so it can help you to protect your eyes and improve your sleep after long hours at the computer.
Pulse Width Modulation (PWM) is a method to control the brightness of your monitor by settings the backlight ON and OFF at high frequency.
Our brain doesn’t perceive this, but we get a lot of eye strain and headaches from this.
You can read more about it here:
How Мonitors Destroyed our Eyes? – Iris – Software for Eye protection, Health and Productivity