Scientists modified the eyes of 5 humans to see an ‘unprecedented’ new color

From the first time I saw Blade Runner and heard Rutger Hauer’s Roy Batty describe “C-beams glittering in the dark near the Tannhäuser Gate,” I’ve wondered what it would be like to see beyond the limits of human vision. What would it feel like to have eyes that could see what we can’t normally see? I envied animals who can see light frequencies in the infrared and superheroes with X-ray vision that let them see like a NASA telescope. And today, I envy five regular human beings who, after having their eye cones temporarily rewired with a laser, were able to perceive a new color outside the typical range of the human eye.

They called this color “olo”—a name derived from the binary code 010, representing the cones in the eye that are activated during its perception thanks to that rewiring. It defies any comparison to anything humans have seen because, well, nobody has seen it except these five lucky individuals. As described in new research published in the scientific journal Science Advances, the subjects of this wild experiment agreed to describe it as a “blue-green of unprecedented saturation.”

How our eyes work

Most humans see the world through three types of light-sensitive cells in the retina, called cones. These detect red, green, and blue light, allowing us to distinguish roughly one million to 10 million colors. That’s enough to spot the difference between a ripe strawberry and a bruised one, or to admire a sunset’s gradient. But a rare few—almost always women—are born with a fourth cone type. These tetrachromats can see up to 100 million colors, spotting nuances invisible to the rest of us. For example, where a trichromat sees a single shade of green grass, a tetrachromat might perceive dozens of subtle variations. Yet even among those with the genetic mutation, true tetrachromacy is rare. The brain must adapt to process this extra input, and most screens can’t display these additional hues.

The people in the experiment didn’t gain the ability to see millions of new colors. Instead, they glimpsed one artificial hue, like a single note added to a familiar song. The effect lasted only as long as the lasers fired, requiring subjects to stare unblinkingly at a fixed point. A twitch or glance away shattered the illusion.

Researchers were able to bypass biology limitations using a system called “Oz”—a nod to the emerald goggles in The Wizard of Oz. First, they mapped individual cones in participants’ retinas using high-resolution scans, labeling each as red, green, or blue. Then, they fired precise laser pulses—100,000 times per second—at specific green-sensitive cones, while tracking minuscule eye movements 960 times per second to keep the aim steady. Normally, activating green cones also triggers neighboring red or blue ones, muddling the signal. But Oz’s precision isolated the green cones, sending the brain a code it had never decoded before. The result was “olo.”

What Olo means for humans

The implications stretch far beyond novelty. By selectively activating or disabling cones, researchers could simulate eye diseases, such as macular degeneration, and test therapies in real time. For color-blind individuals, Oz might trick the brain into perceiving missing colors by rerouting signals from surviving cones. James Fong, a UC Berkeley researcher who was one of the first coauthors in the study, told LiveScience that it could even probe whether humans can learn to interpret entirely synthetic colors: “It may be possible for someone to adapt to a new dimension of color.”

Right now, however, Oz remains a lab curiosity. The system relies on million-dollar lasers, supercomputers, and participants willing to sit motionless for hours. The experiments targeted only peripheral vision—a speck the size of a fingernail at arm’s length—because the retina’s central zone, where vision is sharpest, has cones too tightly packed for current lasers to hit accurately. Scaling this to full sight would require mapping millions of cells and tracking eye movements with zero lag, which is a target quite far from what our current technology can achieve.

“Our method depends on specialized lasers and optics that aren’t coming to smartphones anytime soon,” Fong told LiveScience. For now, olo exists only in flashes—a fleeting crack in the door to a stranger universe.

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