Different Types of Color Blindness and Distinguishing Them

Understanding color vision deficiency

Color vision deficiency means some colors are harder to distinguish. Most affected people do not see only in black and white. Inherited differences are often recognized in childhood; a new color-vision change can instead be associated with eye disease, medication, or another condition and deserves assessment.

Red-green differences

Protan and deutan deficiencies involve differences in long- or medium-wavelength cone signaling. “Anomaly” and “anopia” describe different forms of color-vision deficiency. The effect on daily activities varies. Frequency varies with population, so a single worldwide prevalence figure is misleading.

Blue-yellow differences and achromatopsia

Tritan deficiencies affect blue-yellow discrimination and are less common. Achromatopsia is a different, rare cone-function disorder that may involve markedly reduced color discrimination, light sensitivity, and reduced visual acuity.

Testing and practical support

Color plates and other tests help characterize the difference. Labels, contrast, and accessible color choices can make daily tasks easier. Tinted or filtering lenses may change the appearance of some colors but do not restore missing cone function or reliably normalize color vision.

An experimental study of EnChroma filters in deuteranomaly illustrates why a product’s visual effect should not be confused with a cure. See the NEI’s patient explanation and ask us about testing.