According to a report from the US science website Interesting Science on the 28th, can people see ultraviolet light, which has a shorter wavelength than visible light? The answer depends on a person's age and whether the lens in the eye filters ultraviolet light.
There are photoreceptors on the retina behind the eye that can perceive light and send the detected wavelength signals to the brain through the optic nerve, which interprets the signals as corresponding colors. The human eye has three different types of cone cells that are sensitive to red, green, and blue, the three primary colors of light. In fact, the blue cones can detect some ultraviolet light.
The lens is a transparent curved structure in the eye that focuses light onto the retina, helping people see clearly. Ultraviolet light has higher energy than visible light, which can age the eye structure and increase the risk of cancer. The lens typically filters out ultraviolet light, preventing high-energy wavelengths from reaching the cone cells. For most people, the lens filters out most ultraviolet light, protecting the eyes from harm.
Most young people can still perceive some ultraviolet light. In a small study published in the journal "Public Library of Science ONE" in 2018, all participants from the University of Georgia could see ultraviolet light around 315 nanometers. During the experiment, participants reported seeing a light that appeared as an unsaturated purple-blue color. However, this ability seems to decline around the age of 30, indicating that aging reduces people's ability to see ultraviolet light.
Some individuals can see a broader spectrum of ultraviolet light. Some cataract patients need to have their lenses removed surgically, and they can see ultraviolet light after the procedure. For these individuals and those born without lenses, ultraviolet light appears as a pale blue or pale purple color. A famous example is the Impressionist painter Claude Monet, who underwent cataract surgery in 1923 and saw more blue and purple in the water lilies he painted after the operation.
According to a study published in the Proceedings of the National Academy of Sciences in 2003, the ancestors of vertebrates could see ultraviolet light and had specialized light receptors for ultraviolet light. However, at some point in human evolutionary history, these light receptors became more inclined to detect violet rather than ultraviolet light, possibly as an evolutionary choice to protect vision.
