The key difference between deutan and protan is that deutan is a type of red green colour blindness that is due to an anomaly in the retinal cone called M cone, while protan is a type of red green colour blindness that is due to an anomaly in the retinal cone called L cone.
Anomalous trichromacy is a common inherited colour vision deficiency. It occurs when one of the three cone pigments is altered in its spectral sensitivity. There are three types of anomalous trichromacy: deuteranomaly, protanomaly, and tritanomaly. Deuteranomaly (deutan) is an altered spectral sensitivity of green retinal receptors (M cone), resulting in poor red-green hue discrimination, while protanomaly (protan) is an altered spectral sensitivity of red retinal receptors (L cone) resulting in poor red-green hue discrimination. Tritanomaly, on the other hand, is a rare hereditary colour vision deficiency that affects blue-green and yellow-red/pink (S cone) hue discrimination.
CONTENTS
1. Overview and Key Difference
2. What is Deutan
3. What is Protan
4. Similarities – Deutan and Protan
5. Deutan vs Protan in Tabular Form
6. Summary – Deutan vs Protan
What is Deutan?
Deutan is a type of red green colour blindness that is due to an anomaly of the retinal cone called the L cone. It is an altered spectral sensitivity of green retinal receptors that results in poor red-green hue discrimination. It is by far the most common type of colour vision deficiency. It is hereditary and sex-linked. 5% of European males are affected by this condition. The inherited deuteranomaly is due to a gene mutation of the OPN1MW gene. Acquired cases may also be present due to retinal diseases and issues in the optic nerve.
In this case, green-sensitive cones (M cones) are malfunctioning. A total of 32% cones are M cones. M stands for medium wavelength light that is generally seen as green light. Due to hereditary change, the spectral sensitivity of the M cone is shifted toward longer wavelengths; therefore, it effectively receives too much red light and not enough green light.
Figure 01: Colour Perceptions in Different Types of Colour Blindness
The symptoms of this condition may include confusion between green and yellow or blue or purple, green traffic signals appearing to be pale green or white, and confusion between pink and gray or white. This condition can be diagnosed through a colour vision test by using an anomaloscope. Furthermore, the treatment is through corrective contact lenses or glasses that come in the form of tinted lenses or filters.
What is Protan?
Protan is a type of red green colour blindness that is due to an anomaly of a retinal cone called L cone. It is an altered spectral sensitivity of red retinal receptors (L cone), resulting in poor red-green hue discrimination. L stands for long wavelength, which is generally seen in red right mainly responsible for seeing the red lights. In protan, due to gene mutation, L cone is shifted toward the shorter wavelength; therefore, it does not receive enough red light and receives too much green light compared to the normal L cone. It is inherited, sex-linked, and present in 1% of males. It can also occur due to the gene mutation of OPNILW. In this case, the red-sensitive cones (L cones) are malfunctioning.
The symptoms of this condition include seeing greens, yellows, browns as being more similar shades of colour than normal (especially in low light), purple colour looking more like blue, pink colours appearing to be gray if pink colour is a more reddish pink or salmon colour, and red colours looking darker than normal. Protan colour blindness can be diagnosed through colour vision tests or Ishihara colour tests by using an anomaloscope. Furthermore, the treatment option may include wearing EnChroma glasses and lifestyle management techniques such as practicing memorizing, developing other senses lighting changes (focus on good lighting), using labelling systems, and using accessibility options.
What are the Similarities Between Deutan and Protan?
- Deutan and protan are two types of anomalous trichromacy.
- Both conditions cause red-green colour discrimination problems.
- They can be due to hereditary gene mutations.
- In both conditions, the men are affected more than women.
- Both conditions are due to defective cone cells.
- They are sex linked and follow x linked recessive inheritance patterns.
- Both conditions can be diagnosed through colour vision tests or Ishihara colour tests by using an anomaloscope.
- They are mild conditions.
- They can be treated by wearing specific glasses.
What is the Difference Between Deutan and Protan?
Deutan is a type of red green colour blindness that is due to the anomaly of a retinal cone called M cone, while protan is a type of red green colour blindness that is due to the anomaly of a retinal cone called L cone. Thus, this is the key difference between deutan and protan. Furthermore, deutan is a colour blindness due to hereditary gene mutation of OPN1MW. On the other hand, protan is a colour blindness due to a hereditary gene mutation of OPNILW.
The below infographic presents the differences between deutan and protan in tabular form for side by side comparison.
Summary – Deutan vs Protan
Deutan and protan are two types of anomalous trichromacy. Both conditions have red-green colour discrimination problems. Deutan happens due to the anomaly of a retinal cone called M cone while protan happens due to the anomaly of a retinal cone called L cone. So, this summarizes the difference between deutan and protan.
Reference:
1. “Deuteranopia: Red-Green Color Blindness.” Healthline, Healthline Media, 9 Nov. 2020.
2. Lockett, Eleesha. “Protan Color Blindness: What It Is and What to Do.” Healthline, Healthline Media, 12 May 2020.
Image Courtesy:
1. “Colour perception in different types of colour blindness” By Japs 88 – Own work (CC BY-SA 4.0) via Commons Wikimedia