How to Hide in Plain Sight Trivia Quiz

Answer: Both Protan & Deutan

Our ability to see colour is dependent upon the presence and the functionality of light sensing pigments that reside in the cones in our eyes. When one or more of these cones are either missing or do not function properly, we end up with a CVD - colour vision deficiency. A more apt description is that it diminishes our ability to distinguish shades of colour. The severity of this can range from being virtually unnoticeable to an inability to perceive any colour at all.

Red-green CVD is the most common form of colourblindness. Globally, about 4.25% of the population is affected by CVD to some extent and, of these, approximately 98-99% have some form of red-green colour vision deficiency.

(Footnote) The red-green CVD is sometimes referred to as Daltonism, named after John Dalton, an English scientist who had issues with this colour assessment and released the first scientific study about it in 1794.

Answer: Both Protan & Deutan

It is estimated that 8% of men (1 in every 12) is affected by the red-green CVD whilst only 0.5% (1 in every 200) of women also suffer the same fate. This is because the red-green condition is passed down by a recessive gene linked to the X-chromosome. Men have only one X-chromosome, hence it would only take one genetic change for the affliction to arise. Women, on the other hand, have two X-chromosomes, which would then require two genetic changes to take place to create the condition.

Answer: Protan

A trichromat is one with normal vision. They will have three cones within their retinas to assist with the perception of colours. These are the S-cone, which stands for short-wavelength, and assists us to identify the colour blue, the M-cone (medium wavelength) perceives green and the L-cone (long wavelength) helps us to see red.

A protan is either missing or lacking the full functionality of the L-cone. The alternative way to see this is that they possess abnormal (or no) L-opsins. To explain that a little further, opsins are light-sensitive proteins found in the photoreceptor cells of the eye and, when light hits the pigment, the opsins will change the shape of the chromophore (the specific part of a molecule responsible for its color), which will then trigger an electrical signal to be generated and sent to the brain.

There are two separate forms of protan colour blindness - protanomaly and protanopia. The first arises when the L-cones are there but are not functioning properly and the colour red will appear to be greener in colour. The latter occurs when the L-cones are missing completely, which will mean the affected person will have issues differentiating red from green. The first is obviously the minor form of the condition and, generally, doesn't cause problems in daily life.

Answer: Protan

This next sentence may not make a lot of sense initially, but bear with me... a "neutral point" is a specific wavelength of light that a dichromat perceives as white or grey. Let's break that down into layman's terms.

A trichromat is a person with normal vision, which means they have all three of the cones in their eyes (red, green and blue) functioning. As a result, they will not have a neutral point.

A dichromat only has two of the three cones in working order. Consequently, at some point (wavelength) they will not be able to perceive a colour, instead, it will become either white or grey. For a protanope (protan) that neutral point is on a wavelength sitting at approximately 492 to 495 nanometers. At this point a person with normal vision will see cyan - a brilliant blue-green colour, the protan will see grey.

Because a protan's (or protanope's) ability to see red is reduced they may struggle to separate red from dark grey, along with issues in distinguishing purple shades from various blue shades.

Answer: Deutan

M-cone stands for medium wavelength. In the case of the deutan, they are lacking that particular cone or, if they do have one, it possesses abnormal M-opsins. These cones, which normally would be detecting the colour green, shift to longer wavelengths (neutral point is around about 498 nanometers), which means they will detect too much red colour.

Answer: Deutan

In a similar manner to protan, there are two forms of deutan deficiencies. The first is deuteranomaly, the milder form, means that the afflicted is green weak. The result is that colours red, yellow, green and brown tend to be similar to them and they may also have issues discerning the difference between blues and purples, and pinks with greys. The more serious affliction is deuteranopia which leaves the person green blind and the world that they see will be, predominantly, in shades of yellow and blue.

Most colourblind people are deutans. Deutans represent 6% of the male population and, overall, approximately 75% of all people who are colourblind. One of the big problems that they will endure is the humble traffic light, in particular the red and the amber and, in some cases, the green may look white. Memorizing them helps and the standardization of traffic lights is also an assistance. Some countries do go further, for example, British Rail have changed their red to a blood colour (yes it's still red, but deeper), amber has become yellow and the green has been changed to a bluish green. The eastern provinces of Canada have changed the shapes as a further means of differentiation - square for red, diamond for yellow, and circle for green.

Answer: Tritan

This is a rare form of CVD caused by the retina missing or holding abnormal S-cones, the "S" standing for short wavelength light. People with this condition do not see blue very well and will struggle to separate blue and indigo from green, they may even see these colours as black.

There are some six million retinal cone cells and the S-cones only make up one percent them - which is one of the reasons why it is rare, but it also means that slight damage can easily lead to a sight degradation.

Answer: Tritan

The genetic mutation that causes the blue-yellow form of colour blindness is located on Chromosome 7. This is one of the 23 pairs of human chromosomes and, unlike the X and Y chromosomes, Chromosome 7 is an autosome, rather than a sex chromosome. Chromosome 7 carries the S-opsins that are responsible for detecting blue light. The other pertinent point is that, because it is not a sex chromosome, the distribution of the condition is likely to equal between men and women.

There are other factors that can cause tritan CVD. These include cataracts, glaucoma and macular degeneration through aging.

Answer: Monochromacy

Monochromacy is a broad category that covers a condition known as total colour blindness. People within this category either see no colour or will view the world in shades of grey. Within this category is a subset called achromatopsia, also known as rod monochromacy, which is a very rare and inherited condition where there are no cone cells in the retina or, if there are, they are not functioning. It is estimated that about 1 in 33,000 people are afflicted with this

Those affected by achromatopsia will show symptoms at birth. These will include nystagmus (jiggling eyes), photophobia (extreme light sensitivity) and reduced visual acuity.

Answer: Monochromacy

Monochromacy is a rare form of CVD but those afflicted with the condition will be so in one of two ways - rod or cone monochromacy.

Rod monochromacy, also known as complete achromatopsia, is an inherited condition, where the eye either has no cone cells or non-functioning ones. Those afflicted are described as being truly colourblind and will only view the world in shades of grey. They're more attuned to variations in brightness and, as such, objects that are highly reflective will appear to be near white, low reflective ones will show up as being close to black and, the world in between will be some form of grey.

Because they have no functioning cones, they will be dependent on their rods for vision and, accordingly, this makes them highly sensitive to light in normal conditions. It would be common for a sufferer to wear dark sunglasses whilst indoors. Rod monochromats will have poor vision acuity, about 20/200 vision, and would require very strong lenses to be able to read. Even then, it is likely that they would require large print on surfaces to do so.

A person with the condition known as cone monochromacy, will have only one of the three cones within the retina functioning. Their affliction is then named in accordance with the colour that the cone represents; for example, blue cone monochromacy (BCM) will mean that the blue cone is the only one functioning for that individual. Accordingly, their light detection is purely in the hands of that single cone.

Whilst cone monochromacy will provide better central vision than rod, the individual will still have significantly reduced visual acuity, generally in the range of 20/60 to 20/120. It is highly likely that they will also have the additional issues of photophobia, and nystagmus, along with myopia (short sightedness).