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These simple-looking glasses hold a secret power: they allow people with red-green colour blindness to experience colours which they would normally be unable to see.

Enchroma glasses fact file



Made in


Made by

Enchroma Inc

Museum Reference


On display

Level 3, Technology by Design, National Museum of Scotland

Did you know

Dr Don McPherson, the cofounder of Enchroma, discovered the glasses when he was working on lab glasses for protection from laser eye surgery.

Seeing things in colour

Colour blindness is a condition where a person is unable to see certain colours under normal light. It affects millions of people worldwide and about 2.7 million people in the UK alone.

Visual tests for colour blindness, by Dr. Shinobu Ishihara of Tokyo in 1936.

Colour blindness (or colour vision deficiency) mainly affect men with 1 in 12 men affected and only 1 in 200 women. It can be caused as a result from certain diseases (such as diabetes or multiple sclerosis), but most people have inherited it genetically. People with colour blindness are not usually blind to all colours and the specific colours that they can see depends on the type of colour blindness that they have. 

Holmgren's wool, colour blindness test in which the subject matches various coloured skeins of wool, with instructions, used at the Royal (Dick) School of Veterinary Studies, University of Edinburgh, devised by Alarik Frithiof Holmgren.

The rainbow of colour

People with full colour vision can see an enormous range of different colours. Every colour in the spectrum is a unique wavelength of light. Our eyes don’t have unique detectors for every single colour, instead we have only three different colour detectors – red, green, and blue. These three colour detectors in our eyes, allow us to see all the colours that make up the visible spectrum of light. This works in a similar way to how we can make yellow paint by mixing blue and green together. The colours that we perceive are really just combinations of red, green, and blue. Computers and televisions take advantage of this by using just these three colours to generate every shade that you see on the screen. 


GE 950 colour wheel television receiver, based on John Logie Baird colour system of 1928 and made for the Columbia Broadcasting System by General Electric, 1946.

When you see something yellow on the screen, it is not really yellow. It is just a unique combination of red, green, and blue that has been mixed together.

Red-green colour blindness

Red-green colour blindness is the most common type. This occurs because the red and green detectors overlap more than normal, which means that certain colours are not being detected. However, this doesn’t just mean that only red and green are mixed up, it also means that they can confuse all colours that have red and green in them. This of course includes loads of colours: oranges, pinks, purples, browns and even black! 


How do the Enchroma glasses work?

These glasses made by Enchroma have tried to tackle the issue of red-green colour blindness with special filters built into the lenses. These special optical filters remove small slices of light where the red and green cones overlap the most in the eye of the colour blind. This re-establishes a more accurate ratio of light entering the three photopigments so the color blind enjoy a more normal spectral response. 

These glasses have allowed people with colour blindness to experience enhanced colour, an improved ability to differentiate hues of colours, and better depth and detail perception.

See these Enchroma colour blind glasses in our Technology By Design gallery at the National Museum of Scotland.

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