Protan colour blindness and Duetan colour blindness are technical terms for the type of colour vision deficits there are – these are shortened from Protanopia and Deuteranopia or deuteranomaly. There are numerous mild protan glass and mild duetan glass to enable people with varying degrees of colour deficit to see colours like everyone else. However iRo Lenses are designed for all types of colour vision problems. We can adjust the glass to suit your vision type, and any prescription you may have too.


How it Works


The term red-green colour blindness is split into two different subtypes. On one side people either lack or have anomalous long wavelength sensitive cones (protan colour vision deficiency), which are more responsible for the red part of vision. On the other side deutan colour vision deficiencies, which again are split into two different types:

  • Dichromats: Deuteranopia (also called green-blind). In this case, the medium wavelength sensitive cones (green) are missing at all. A deuteranope can only distinguish 2 to 3 different hues, whereas somebody with normal vision sees seven different hues.
  • Anomalous Trichromats: Deuteranomaly (green-weak). This can be everything between almost normal colour vision and deuteranopia. The green sensitive cones are not missing in this case, but the peak of sensitivity is moved towards the red sensitive cones.


Protan – is the red deficiency


People who are affected by protan colour blindness are less sensitive to red light. Protans have difficulties to distinguish between blue and green colours and also between red and green colours. When comparing the two spectrums, you can see that there are different colours and shades of colours which are hard to distinguish for a protanopic person.

So those people are not only blind on red and green colours but a lot more. Which in reality, the term red-green colour blindness is misleading and gives a wrong impression of protan colour blindness (and also deutan colour blindness).


Deutan – is the green deficiency


People who are affected by Deutan colour vision deficiencies is by far the most common form of colour blindness. This subtype of red-green colour blindness is found in about 6% of the male population, mostly in its mild form deuteranomaly.

There is also a third term called Tritanopia which is usually caused by a genetic mutation. Unlike other forms of colour-blindness, Tritanopia is not caused by an x-linked recessive trait. That is why it is equally present in males and females. Additionally, Tritanopia can be caused by blunt trauma to the eye or exposure to ultraviolet light.

People can have a sliding scale combination of Protans and Duetans which can be established through testing from a qualified Optometrist. iRo Lenses can be adjusted to suit any combination of Protan and Deutan, as well as for any prescription lenses. Colour Blind Glasses available in Australia work for all types of vision deficiencies. A quick, simple check using our unique in-home testing kit will enable you to determine your level and depth of colour vision deficiency and then see exactly which iRo lens works for you with the in-home iRo Lenses testing kit.