Going from a world of grays to one awash in rich yellows and striking blues would be overwhelming for anyone. For one colorblind man, who can’t tell the difference between reds and greens, the EnChroma glasses helped bestow that experience.

There’s one video on Katherine Empey’s YouTube channel, and it’s of her little brother unwrapping a birthday present. With kids jumping around him in anticipation, the Pennsylvania man puts on the glasses and, as if stunned by the sheer force of new light bombarding the rods and cones behind his eyes, he stops. Then he begins looking around, taking in the color of his kids’ clothes and the flowers his family bought just for the unwrapping. When asked if the experience is really different, he simply nods, on the verge of tears.

EnChroma glasses were developed by San Francisco-based engineer Don McPherson, and sort of by accident. One day he lent a friend a pair of protective glasses normally used during laser corrective surgery. When his friend put them on, he was shocked to find how much color he’d been missing all along.

One of the standout benefits of wearing EnChroma glasses is their staying power. As the wearer’s brain gets used to filtering incoming light through the glasses’ lenses, the photoreceptors interpreting the signal can adapt and actually change, so that when the glasses are removed the effect still remains.