Infrared Contact Lenses Let People to See in the Dark Even With Eyes Closed

Researchers have developed a new type of contact lens that allows people to see artificial near-infrared light even in the dark.

Rudy Blalock

Published: 5/22/2025, 11:54:55 PM EDT

Infrared Contact Lenses Let People to See in the Dark Even With Eyes Closed — A young woman wearing contact lens in a stock photo. (Shutterstock)

A research team has developed a new type of contact lens that allows people to see near-infrared (NIR) light, enabling vision in the dark even with their eyes closed.

Led by Professor Xue Tian and Professor Ma Yuqian at the University of Science and Technology of China (USTC), the researchers published their study on May 22 in the scientific journal Cell, according to a press release.

Expanding Human Vision

Humans naturally see only a small part of the electromagnetic spectrum, known as visible light, which ranges from about 400 to 700 nanometers. Infrared light, which is beyond the red end of this spectrum, is invisible to the naked eye. Over half of the sun’s energy comes in the form of infrared light, but people cannot see it without special equipment.

The new upconversion contact lenses (UCLs) enhance the way people see color, according to the study.

This is achieved by using upconversion nanoparticles (UCNPs) embedded in soft, transparent polymers. Such nanoparticles absorb invisible NIR light and emit visible light, making the previously unseen part of the spectrum visible to the wearer.

How the Lenses Work

To create these lenses, the researchers modified the surface of the nanoparticles and carefully matched the optical properties of the polymers. This allowed them to achieve high concentrations of nanoparticles—up to 9 percent—while keeping the lenses more than 90 percent transparent, allowing users to still see their surroundings normally.

The lenses are flexible, hydrophilic, and biocompatible, making them comfortable and safe to wear.

Tests showed that both mice and human participants wearing the lenses could detect NIR light and even distinguish between different frequencies of NIR flickers.

Notably, the ability to sense NIR light remained strong even when eyes were closed, because NIR light can penetrate tissues like eyelids far more effectively than visible light. For example, only 0.4 percent of visible green light passes through a mouse’s eyelid, but more than 23 percent of NIR light does, according to the study.

Seeing in the Dark and Through Obstacles

When wearing the lenses, human participants could identify NIR flashes in both total darkness and under normal room lighting. With their eyes closed, their sensitivity to visible light dropped sharply, but their ability to detect NIR light did not.

Researchers found that closing the eyes improved the signal-to-noise ratio for NIR detection, making it easier to sense coded flashes or patterns.

The lenses also allowed participants to recognize basic spatial patterns and to interpret flickering NIR signals, such as Morse code.

However, because the upconverted light scatters before entering the eye, the lenses currently only provide a coarse perception of images, researchers wrote in the study. To address this, the team developed a wearable eyeglass system that integrates the same nanoparticle technology, enabling high-resolution NIR vision comparable to normal sight, UTSC noted in its press release.

Introducing Infrared Color Vision

To handle the wide range of NIR wavelengths found in nature, the team created trichromatic upconversion contact lenses (tUCLs). Such lenses use special nanoparticles that can convert three different NIR wavelengths into the three primary colors of visible light—red, green, and blue.

With these, users can distinguish multiple NIR “colors,” allowing for the perception of a broader NIR spectrum and the precise recognition of multi-dimensional, encoded data.

In tests, participants were able to match and recognize NIR colors and decode color-coded light signals. The tUCLs also allowed users to see colorful NIR-reflective images, revealing hidden patterns and differences in objects that look the same under normal light.

Potential Applications and Future Directions

This technology opens up new possibilities for security, anti-counterfeiting, and the treatment of color vision deficiencies. The ability to see in darkness or through fog and dust could help in rescue operations and other challenging environments, researchers said in the study.

While the current lenses work best with artificial NIR sources, such as LEDs, detecting natural NIR in the environment remains a challenge.

The researchers are working to further improve the sensitivity and image resolution of the lenses.