The invisible spectrum: Can humans see ultraviolet light?

The spectrum of

visible colors

includes many hues that remain unseen by humans, such as

ultraviolet light

, which many animals can perceive but eludes most of us. According to experts speaking with Live Science, whether humans can see ultraviolet wavelengths hinges on age and whether one's eyes are equipped with

UV-filtering lenses

.
In the human eye, the retina's photoreceptors detect light and send signals to the brain, translating them into colors.

Notably, our blue-detecting cones are capable of sensing some ultraviolet light. However, "the lens— the clear, curved structure in the eye that focuses light onto the

retina

to help us see more clearly—filters out UV light, so the high-energy wavelength never actually reaches the cones," explained Michael Bok, a biologist at Lund University.
For most individuals, the lens effectively blocks most UV wavelengths to shield the eyes from potential damage, such as aging eye structures and increasing cancer risks. Interestingly, a 2018 study from the University of Georgia found that all college-aged participants could perceive UV light at approximately 315 nanometers, seeing it as a "desaturated violet-blue." However, this capability declines around age 30.
In cases where individuals underwent

cataract surgery

prior to the 1980s—where the cloudy lens was removed without replacement—or for those born without a lens, UV light appears as pale blue or violet. Impressionist painter Claude Monet, who had cataract surgery in 1923, famously saw enhanced blue and purple tones in his later works.
While human adults generally cannot see UV light, many animals, including mammals like dogs, cats, and reindeer, retain this ability throughout their lives. This capability provides significant advantages in their environments, aiding in prey detection and navigation, among other uses.