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Metasurface-Based Contact Lenses Could Correct Red-Green Color Blindness

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A custom contact lens could offer a convenient way to help people who experience color blindness.

Researchers at Tel Aviv University (TAU) embedded large-scale, plasmonic metasurfaces into off-the-shelf contact lenses and studied the ability of the contacts to serve as visual aids for color vision deficiency. Based on simulations, the researchers observed that their metasurface-based contact lens could restore lost color contrast and improve color perception up to a factor of 10.

The study specifically addressed deuteranomaly, a condition in which the photoreceptor responsible for detecting green light responds to light associated with redder colors. This vision problem is correctable, but challenging to correct with a comfortable, compact device.

“Glasses based on this correction concept are commercially available; however, they are significantly bulkier than contact lenses,” researcher Sharon Karepov said. “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.”

Metasurface-based contact lenses correct color vision deficiency, Tel Aviv University.

These images illustrate the effect a metasurface-based contact lens would have on a person with deuteranomaly. The left image shows the original scenario while the middle image is how the scene would look to a person with deuteranomaly. The image on the right represents the scene viewed with deuteranomaly and corrected with the new contact lenses. Courtesy of Sharon Karepov, Tel Aviv University.

The researchers developed a technique to transfer metasurfaces from their initial flat substrates to curved surfaces such as contact lenses. They tested the optical response of the metasurface after every step of the new fabrication procedure and acquired microscopy images to examine the structure of the metasurface. Their measurements showed that the metasurface’s light manipulation properties did not change after transfer to the curved surface, indicating that the fabrication process was successful.

The researchers then used a standard simulation of color perception to quantify the deuteranomaly color perception before and after introducing the optical element. They found an improvement of up to a factor of 10 and showed that visual contrast lost due to deuteranomaly was essentially fully restored.

Although clinical testing would be needed before the contact lenses could be marketed, the researchers said that manufacturers could embed the metasurface during the molding stage of contact lens fabrication or thermally fuse the metasurface to a rigid contact lens. They plan to keep studying and improving the metasurface transfer process. The new fabrication process could be used to embed metasurfaces into other nonflat substrates as well, Karepov said.

The research was published in Optics Letters, a publication of OSA, The Optical Society (www.doi.org/10.1364/OL.384970).

Photonics Spectra
May 2020
GLOSSARY
ophthalmology
The branch of medicine involved in the study of the anatomy, functions, diseases and treatments of the eye.
Research & TechnologyeducationEuropeTel Aviv Universitycontact lensesmaterialsmaterials processingopticslensesBiophotonicsophthalmologymedicalnanometasurfaceplasmonicsmetalensoptical designoptical fabricationCOTS lensesTech Pulse

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