Deutan Factoids:

• M-cone deficiency
• Less discrimination of the green colors
• Similar functionally to Protans
• Significantly more common in males (mutation on X-chromosome allele)
• Commonly genetic cause, but may be acquired

A person with a Deutan deficiency called Deuteranomaly (5% of males) is considered to be “green weak” This deficiency is similar to the Protan type as there is also difficulty in discriminating between red – orange – yellow – green portions of the color spectrum … they are confused as being very similar. These colors seemed similar to the red portion of the spectrum.

Deuteranopia (1% of males) has the same hue discrimination problems as the Protonope, but without the dimming.

Tritan Factoids:

• S-cone deficiency
• Less discrimination of the blue colors
• Typically an acquired condition (genetic basis is very rare)
• May be the most common color deficiency type
• No gender bias
• Many tests that have been commonly administered in the past (Ishihara as an example) do not test for S-cone deficiencies
• More common with age
  • Pharmaceutical agent toxicity may cause
  • Neurologic conditions, diseases and discorders may cause
  • Changes to the crystalline lens (cataracts) may cause

Red-green color deficiencies are the most common type of genetic color vision deficiency, originating from an X-chromosome mutation which results in a color deficient allele.

This is a recessive trait, but females that are heterozygous (trait only on one X-chromosome) will not exhibit the inherited trait, rather it requires a homozygous condition where the trait is manifested on both chromosomes, i.e. inherited from both parents.

Males, that inherit trait on the single X-chromosome maternally, exhibit red-green color deficiency.