Blue light—short wavelengths of visible light emitted by smartphones, computers, and TVs—impairs the eye’s ability to distinguish fine detail more than any other wavelength, according to a new study from the University of Georgia. This finding could help inform future lighting technologies, digital display design, and research on visual performance.
Researchers tested 60 young adults in a vision experiment. Participants viewed adjustable blue, green, yellow, red, and broadband light sources and indicated when they could distinguish two separate points of light.
“When the light spreads more on the retina, those two light sources have to be farther apart before someone can tell they are separate,” said Yaw Buabeng, lead author of the study and a doctoral candidate in the Franklin College of Arts and Sciences Department of Psychology. Buabeng, who earned his optometry degree from Kwame Nkrumah University of Science and Technology in Ghana, practiced professionally as an optometrist before pursuing graduate studies at UGA.
“With blue light,” he said, “the two points had to be separated much farther than with the other colors, showing that blue light produced the greatest amount of light scatter and optical aberrations. Green, yellow, red, and broadband light produced less.”
Many factors, like light scattering and imperfections in the eye’s optics, keep light from coming into sharp focus on the retina, Buabeng said. Blue light is more affected by these image-blurring effects than longer wavelengths, making it harder to distinguish fine details. In everyday life, people encounter blue light through sunlight, LED lighting and digital devices.
The study also found that iris pigmentation influenced how far apart the two light points needed to be before viewers could distinguish them as separate points. Using a standardized iris color chart, researchers classified each participant’s eye color before analyzing the results. Participants with lighter-colored irises, particularly blue eyes, experienced greater light scatter than those with darker brown irises.
“People with darker brown eyes have higher levels of melanin in the iris and in the back of their eye, in a tissue called the retinal pigment epithelium, which absorbs excess light scattering within the eye” Buabeng said. “Lighter-colored irises contain less melanin, allowing more light scatter.”
The findings may help explain why some people experience greater sensitivity to bright light or glare than others, he said.
Protecting your vision
Although the study did not evaluate blue light filtering technologies or eyewear, Buabeng nonetheless recommended such precautions for some people.
“Many electronic devices already include blue light filtering features, which I believe can be beneficial,” he said. “From a clinical perspective, I also recommend blue light filtering glasses, particularly for people who spend long hours outdoors or in front of digital screens.”
Previous research, Buabeng said, has linked prolonged exposure to high-energy blue light with oxidative stress in the macula, the central region of the retina responsible for sharp, detailed vision. Over time, this oxidative stress can cause problems.
“Prolonged exposure to blue light is considered one of the contributing risk factors to macular degeneration,” he said. “The important thing is that this damage does not usually happen overnight. It accumulates over time.”
‘You are what you eat’
Buabeng said his background as an optometrist inspired the research and complements his work in psychology.
“In vision science, psychology helps us understand how the brain processes visual information, how we perceive what we see, and how our responses reflect what’s happening inside the brain,” he said. “By combining optometry and psychology, we can better understand both the optical and neural processes that shape human vision.”
This research is part of Buabeng’s broader work examining factors that influence vision. In previous research, he examined the role of macular pigment—nutrients obtained primarily from green leafy vegetables and brightly colored fruits—in protecting the eye.
In that earlier research, Buabeng found that higher levels of macular pigments may help protect the eye by absorbing high-energy blue light before it reaches the macula. He said maintaining a diet rich in leafy green vegetables and colorful fruits can help increase those protective pigments.
“There’s a saying: ‘You are what you eat,’” Buabeng said. “The health of your eyes reflects that, too.”
