A display device and a display system are disclosed. In one aspect, the display device includes a pixel unit including a first display area and a second display area, a controller configured to control the pixel unit to display a first image in the first display area and a second image in the second display area, a first polarization layer formed over the first display area and having a first polarization direction, and a second polarization layer formed over the second display area and having a second polarization direction different from the first polarization direction. The second image includes a light therapy image or an image adjusted for color blindness.