vision that is 20/200 or worse in both eyes (20/200 vision is the ability to see at 20 feet what a normal eye can see at 200 feet)
a form of dichromacy characterized by lowered sensitivity to yellow light; so rare that its existence has been questioned
dichromacy characterized by a lowered sensitivity to green light resulting in an inability to distinguish green and purplish-red
rare form of dichromacy characterized by a lowered sensitivity to blue light resulting in an inability to distinguish blue and yellow
temporary blindness caused by exposure to sunlight reflected from snow or ice
dichromacy characterized by lowered sensitivity to long wavelengths of light resulting in an inability to distinguish red and purplish blue
the state of being blind or lacking sight
established by or founded upon law or official or accepted rules
