New contact lenses allow colourblind people to tell green from red

Prototype contact lenses that allow colourblind people to tell green from red without needing a pair of ‘bulky sunglasses’ are being developed

  • The technology involves an ultra-thin material that changes the colour of light
  • The team developed a way to ‘print’ the new material on to a curved surface 
  • It is not commercially available yet and still has to go through clinical trials
  • Developers say the tiny lens will replace the bulky sunglasses currently used 

Contact lenses capable of allowing a colourblind person to tell red from green without a bulky pair of sunglasses are being developed.

Researchers from Tel Aviv University in Israel say their contact lenses can restore lost colour contrast and improve colour perception by a factor of ten.

The lenses are particularly for people who have problems telling the difference between red and green – known as deuteranomaly.

It involves a tiny gold ellipse material being embedded in an off-the-shelf contact lens to correct the condition that primarily occurs in men.

The team hope to be able to expand their new technology to allow for any type of colour blindness to be treated from a single contact lens. 

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The left image shows the way someone with red green colourblindness would see the scene and on the right is the view through contact lenses – much closer to the original red tree 

To create the lenses the team incorporated ultra-thin optical devices known as metasurfaces with the type of contact lenses you buy off the shelf.

The new type of customizable lens could offer a ‘convenient and comfortable’ way to help people who experience various forms of colour blindness, the authors said.

‘Problems with distinguishing red from green interrupt simple daily routines such as deciding whether a banana is ripe,’ said Sharon Karepov from Tel Aviv University.

‘Our contact lenses use metasurfaces based on nano-metric size gold ellipses to create a customized, compact and durable way to address these deficiencies.’

Finding a way to ‘print’ these metasurfaces on to a curved surface is what has enabled them to make it available on contact lenses.

They haven’t been tested on people yet but based on simulations of colour vision deficiency, their new metasurface-based contact lens can restore lost colour contrast and improve colour perception up to a factor of 10.

Deuteranomaly, which occurs mostly in men, is a condition in which the photoreceptor responsible for detecting green light responds to light associated with redder colours instead. 

Scientists have known for more than 100 years that this vision problem can be improved by reducing detection of the excessively perceived colour.

Unfortunately achieving this correction in a comfortable and compact device is challenging and so far limited to bulky sunglasses, the team said.

‘Glasses based on this correction concept are commercially available, however, they are significantly bulkier than contact lenses,’ said Karepov. 

‘Because the proposed optical element is ultrathin and can be embedded into any rigid contact lens, both deuteranomaly and other vision disorders such as refractive errors can be treated within a single contact lens.’

The biggest problem was finding a way to ‘print’ the correction filters on to the lenses and that is where ‘metasurfaces’ came in.

They are artificially fabricated thin films designed with specific optical properties. 

This image of a bright red tree is the real world scene but for someone with red green colourblindness the red would appear muted and closer to the green (top right) but the corrective lenses bring their vision closer to the original view (bottom right)

Metasurfaces made of nanoscale gold ellipses have been extensively studied in the past few decades and can be designed to achieve specific effects on the light transmitted through them. 

‘We developed a technique to transfer metasurfaces from their initial flat substrate to other surfaces such as contact lenses,’ said Karepov. 

‘This new fabrication process opens the door for embedding metasurfaces into other non-flat substrates as well.’

Although clinical testing would be needed before the contact lenses could be marketed, the researchers say that manufacturers could embed the metasurface during the moulding stage of contact lens fabrication.

The metasurfaces could also be thermally fused to a rigid contact lens.

They plan to keep studying and improving the transfer process and test it for other applications beyond treating colourblindness. 

The research has been published in the journal Optics Letters. 


Approximately one in 20 people suffer from colour blindness, a condition that makes the world a duller place to look at.

According to the NHS, it affects 1 in 200 women in the world and 1 in 12 men.

There are four kinds of colour blindness known as protanopia, dueteranopia, tritanopia and achromatopsia.


Protanopia involves defective or absent long-wavelength cones in the retina; these photoreceptor cones are responsible for the perception of red light. Protans find it difficult to distinguish between red and green colours, and also between blue and green. 


Deuteranopia is a condition where the green photoreceptor cone is missing from the retina. As a result, it is much harder for deutans to distinguish green from red, as well as some grays, purples and a greenish blue. Along with protanopia this is one of the most common forms of colour blindness. 


Tritanopia is a complete lack of the short-wavelength cones in the retina that receive blue light. People with this very rare form of colour blindness confuse light blues with greys, dark purples with black, mid-greens with blues and oranges with reds.   


People with total acromatopsia cannot perceive any colours at all and can only observe the world in black and white and shades of gray.

The retina of the eye has two types of light-sensitive cells; rods and cones. 

Both are found the layer at the back of your eye which processes images. 

Rods work in low light conditions, but cones work in daylight and are responsible for colour. People who have colour blindness have a problem with the cones in their retina. 

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