blue light

Researchers from The University of Toledo have found the chemical reason behind why blue light damages our eyes over time, contributes to macular degeneration, and can even cause blindness. Since we’re spending more time in front of screens than ever before, this finding might be a big step forward toward preventing eyesight deterioration.

Sunlight contains all the colors of the light spectrum and it is our primary source of blue light exposure. All digital devices with screens, such as computers, televisions, smartphones, etc. emit blue light as well. In addition to that, light pollution today is almost ubiquitous. It is associated with higher risk for cardiovascular disease, insomnia, depression,  irritable bowel syndrome and even cancer. Unfortunately, overexposure to blue light can also contribute to age-related macular degeneration,

Researchers from Ohio were dedicated to discover the mechanism behind blue light related, long-term damage to eyes. They published their findings in Scientific Reports. Reactive oxygen species (ROS) seem to be the main to blame.

“Retinal is the light-harvesting antenna of photoreceptors in pretty much any animal, including humans,” Ajith Karunarathne, an assistant professor from UT’s Department of Chemistry and Biochemistry and the study’s corresponding author, said for Inverse. “That’s how a photoreceptor knows that light has hit it.”

Basically, retinal is essential for the photoreceptor cells in the retina to translate light into visual information. Hence, a constant supply of the molecule in the eye is needed. Unfortunately for anybody reading this article on their screen, when retinal is exposed to the blue light, it produces toxic molecules that can permanently damage the photoreceptor cells.

When retinal absorbs the energy from blue light, it transfers it to oxygen, which is abundant in the eye. Over time, this creates various ROS (free radicals) that can damage photoreceptors.

“We are being exposed to blue light continuously, and the eye’s cornea and lens cannot block or reflect it,” Karunarathne said in a statement. “It’s no secret that blue light harms our vision by damaging the eye’s retina. Our experiments explain how this happens, and we hope this leads to therapies that slow macular degeneration, such as a new kind of eye drop.”

Karunarathne treated some cells with retinal, exposed some to blue light, and treated other cells to both blue light and retinal. He concluded that nothing happens if retinal is added and cells are kept in the dark or if cells are exposed to blue light without retinal. But the combination of the two cause damage to photoreceptor cells. Interestingly, this combination causes damage to other cells in the body too, including cancer cells and nerve cells.

“These results indicate that prolonged exposure of cells to (blue light-excited) retinal leads to cell death,” write Karunarathne and his co-authors in the paper. “These findings suggest that retinal exerts light sensitivity to both photoreceptor and non-photoreceptor cells, and intercepts crucial signaling events, altering the cellular fate.”

The cell death caused by blue light excited-retinal usually happen when a person is about 50 or 60 years old, which coincides with the time when age-related macular degeneration usually develops. However, there may be ways to protect your vision if you have to use screens, like using red-shifting features.

Karunarathne’s group has set up a new goal to explore which molecules can protect us from damage caused by blue light excited-retinal.

“We are trying to screen a library of molecules to see if we can identify any molecules that will reduce toxicity,” he says. The study identified a vitamin E derivative molecule that could protect against the ROS damage.

The worrying fact is, we spend ever more time in front of screens.  On average, people’s screen time is over 10 hours a day. Unfortunately, over time, we could see the effects of blue light excitement on retinal in younger people. Now when we know how it works, researchers will try to find protection from unwanted consequences.

So, what can you do in the meantime? When you browse your phone during nighttime in the dark, your pupils become dilated. That way, a lot of unobstructed blue light is getting in. Karunarathne’s group recommends leaving your light on when working late hours.

Learn more about blue light in the interesting video below:

By Andreja Gregoric, MSc