Imagine strolling through a dense forest at midnight, seeing every tree, rock, and winding path without a flashlight. No bulky night-vision goggles, no cameras, no batteries, and no blinding torches. Just your eyes aided by a pair of smart, nearly invisible contact lenses. It sounds like something straight out of a spy thriller, but recent breakthroughs in nanotechnology are bringing this vision into focus. Scientists at the University of Science and Technology of China have developed contact lenses that allow humans to perceive infrared (IR) light, a spectrum once reserved for military-grade night-vision devices and snakes hunting in the dark.

The Limits of Human Vision

For decades, the idea of enhancing human vision has fascinated scientists and science fiction fans alike. From night-vision goggles used by soldiers to thermal cameras in wildlife documentaries, we've long sought to extend our natural limitations. Now, a new class of contact lenses developed by Chinese scientists at the University of Science and Technology of China allows humans to perceive infrared light, a spectrum that is usually reserved for bats, snakes, and sci-fi.

Before we dive into the complexity of this technology, let’s take a quick recap of the visible light and IR spectrum. Our eyes are remarkable, but they only detect a narrow band of the electromagnetic spectrum, which we call visible light, ranging from about 400 to 700 nanometers in wavelength. Just beyond this spectrum lies infrared, which spans from 700 nanometers to 1 millimeter — a longer range of wavelengths often associated with heat. Though imperceptible to most complex life, infrared light is emitted by nearly everything around us, especially warm objects like living creatures, engines, and electronics.

The infrared range is further divided into near-infrared (just beyond visible red light), far-infrared, and thermal radiation. With the right sensors, this otherwise invisible world becomes accessible, revealing everything from a person’s body heat to hidden animals in the dark. The ultimate challenge has always been packaging this technology in a form as convenient and seamless as human sight.

A Lens That Sees the Invisible

So, how is the functionality of an infrared camera packed into something as small and thin as a contact lens? The answer lies in nanotechnology. Specifically, ultra-thin materials like graphene or specially engineered upconversion nanomaterials can detect and convert near-infrared (NIR) light in the range of 800–1600 nm into visible wavelengths. A recent breakthrough involved the creation of NIR upconversion contact lenses (UCLs) that are transparent, flexible, hydrophilic, and biocompatible, making them safe and wearable.

These lenses can convert infrared radiation into visible light through a process called upconversion, where low-energy NIR photons are absorbed and re-emitted as higher-energy visible photons. This process effectively allows the eye to perceive infrared radiation as visible light.

Infrared Color Vision: A New Dimension of Sight

In a 2025 study, both mice and human participants wearing UCLs were able to perceive and distinguish spatial and temporal patterns encoded in NIR light. Even more remarkably, researchers developed trichromatic UCLs (tUCLs) that enable humans to perceive NIR light as distinct “colors.” By mimicking how our cone cells process red, green, and blue, these lenses enable users to experience a new kind of “infrared color vision,” a capability previously unattainable with the naked eye.

Compared to traditional night-vision goggles, which are bulky, power-hungry, and conspicuous, these lenses are a radical shift. They promise hands-free, unobtrusive, always-on night vision.

Why It Matters: From Vision Enhancement to Real-World Applications

Expanded Color Vision for the Colorblind: Trichromatic UCLs offer a potential new approach to helping colorblind individuals. By translating invisible NIR light into a visible spectrum using alternative color coding, these lenses could allow people with red-green deficiencies, for example, to differentiate objects based on distinct NIR “colors” rather than relying on visible light alone.

Advanced Imaging for Professionals: Surgeons, forensic investigators, and engineers could benefit from lenses that provide real-time multispectral imaging, revealing features or materials otherwise invisible under normal lighting.

Transparent NIR upconversion contact lenses (UCLs) have been developed with high efficiency and biocompatibility. These lenses are not only safe for prolonged use but also highly effective at converting invisible NIR radiation into visible light.

Mice using UCLs could detect infrared spatial and temporal patterns, demonstrating that this technology can meaningfully extend the limitations of natural perception.

A Glimpse Into the Future of Human Vision

We stand on the brink of a new visual age, one where the darkness no longer conceals and the invisible becomes visible. Whether used for safety, science, or simply curiosity, these lenses invite us to imagine a world where nothing is out of sight.

And perhaps most intriguingly, this is just the beginning. If we can see in the dark with a lens, what’s next? Augmented reality directly on the eye? Microscopic telescopic vision? One thing’s certain: the future looks bright even in the dark.