Red-green color blindness: Difficulty distinguishing between red and green.

Blue-yellow color blindness: Trouble distinguishing between blue and yellow hues.

Complete color blindness (monochromacy): Rare condition where the person cannot see any colors at all.

Now, red-chroma lenses are specially designed eyewear that can help enhance color perception, particularly for people with red-green color blindness. These lenses are tinted with a color filter that helps to differentiate between colors that would normally appear similar to someone with color vision deficiency.

How red-chroma lenses help:

Enhanced contrast: The red-chroma lens filters out certain wavelengths of light, which can help people with red-green color blindness better differentiate between reds and greens by enhancing the contrast.

Improved color distinction: These lenses specifically target the color ranges where people with red-green color blindness typically struggle, making it easier for them to distinguish between colors that would otherwise be indistinguishable.