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Of the 1,000 people in the world, 8 men and 5 women suffer from color vision impairment, commonly known as “color blindness”. Individuals with color vision impairments vary greatly. Some people are only insensitive to certain wavelengths of light, such as red-green color blindness. But the most serious color blindness cannot distinguish all colors, and is called total color blindness.
The cause of color vision impairment is abnormal cone cells in the human eyes. Cone cells are a type of color vision and strong light-sensing cells on the retina. They are named because their outer nodes are conical. There are three types of cone cells of S-cones, M-cones and L-cones that distinguish colors of blue, green, and red, respectively. Taking deuteranomaly as an example, when the M-cones that are mainly responsible for absorbing green light are abnormal, the light waves it receives will coincide with the red spectral range that the L-cones are responsible for, which will cause the human eyes not to be able to distinguish these colors.
Obstacles in color discrimination not only affect people’s appreciation of beauty, but also disrupt people’s daily lives. Colorblind patients will be restricted in their career choices, especially in art, medicine, chemical engineering, electrical engineering, and telecommunications that require color discrimination. Fortunately, the study published in March 2020 by the University of Tel Aviv, Israel, may be able to color the lives of these patients.
By combining ultra-thin optics with existing contact lenses, the team successfully developed a nano-structured contact lens that can greatly alleviate the symptoms of red-green amblyopia, which is also the most common color vision disorder. In order to alleviate color blindness, the method that can be used efficiently is to reduce the excessive intake of color by cone cells. Previously, this technology could only be applied to external eyeglasses. But now, contact lenses developed by the Sharon Karepov team can better help people ease color vision barriers. These contact lens use nano-metric size gold ellipses and are tailored to provide patients with a convenient and lasting solution. This research was also published in The Optical Society (OSA) journal Optics Letters.
However, scientific research results are not achieved overnight. The shape of the contact lens is the first troublesome problem to solve. The researchers faced an obstacle that previously, metasurfaces are only made on flat surfaces, so how to adjust to the curved surfaces of contact lenses. They then developed a technique to successfully solve this problem. This new fabrication process can not only be applied to contact lenses, but also to other non-flat substrates as well.
What’s more, another good news is that this technology has obtained additional effects. Scientists can fine-tune the nanoparticles on the metasurface to manipulate the light passing through it, thus alleviating other common vision problems in one fell swoop.
“The optical components we developed are ultra-thin and can be embedded in any rigid contact lenses, so whether it is amblyopia or other visual impairments, such as myopia, hyperopia and astigmatism, a small pair of contact lenses can solve all these problems.” Introduced by Karepov. This type of contact lens has not yet entered clinical trials, but researchers have prepared for its further technical development and clinical application. If this technology can be put on the market, it is surely great news to patients with color blindness and color vision impairment.
Reference:
Sharon K., Tal E. (2020). Metasurface based contact lenses for color vision deficiency. Opt. Lett. 45, 1379-1382.