Most people perceive color normally because the photoreceptors in their eyes contain all three types of photopigments. Some people do not naturally perceive color normally because their photopigment sensitivities are shifted. Enchroma lenses filter and shift colors so that a color deficient person can see the colors more normally. This can be life-changing for some people. The lenses do work better in a certain type of color deficiency, so it is important to have the correct color-deficient diagnosis so you can be assigned the correct Enchroma lens option. They come in sunglasses and clear lenses. You can also get your glasses prescription in them!