Prefix
deuter-
Alternative form of deutero- used before a vowel.
Dichromacy conditions are labeled based on whether the "first" ( Greek : prot-, referring to the red photoreceptors), "second" (deuter-, the green), or "third" (trit-, the blue) photoreceptors are affected. Source: Internet
They work by notching out wavelengths that strongly stimulate both red and green cones in a deuter- or protanomalous person, improving the distinction between the two cones' signals. Source: Internet