It creates 'cell killers.'

Researchers at The University of Toledo believe they've figured out the process by which blue light from digital devices and the sun damages the eyesight.

It transforms vital molecules in the eye’s retina into cell killers, according to a study they published recently in the journal Scientific Reports. And that leads to age-related macular degeneration.

“We are being exposed to blue light continuously, and the eye’s cornea and lens cannot block or reflect it,” said Dr. Ajith Karunarathne, assistant professor in the UT Department of Chemistry and Biochemistry. “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.”

Macular degeneration is the death of photoreceptor cells in the retina. Those cells need molecules called retinal to sense light and trigger a cascade of signaling to the brain, a press release from the University of Toledo explains.

“You need a continuous supply of retinal molecules if you want to see,” Karunarathne said. “Photoreceptors are useless without retinal, which is produced in the eye.”

 

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Karunarathne’s lab found that blue light exposure causes retinal to trigger reactions that generate poisonous chemical molecules in photoreceptor cells.

“It’s toxic. If you shine blue light on retinal, the retinal kills photoreceptor cells as the signaling molecule on the membrane dissolves,” said Kasun Ratnayake, a PhD student researcher working in Karunarathne’s cellular photo chemistry group. “Photoreceptor cells do not regenerate in the eye. When they’re dead, they’re dead for good.”

Karunarathne introduced retinal molecules to other cell types in the body, such as cancer cells, heart cells and neurons. When exposed to blue light, these cell types died as a result of the combination with retinal. Blue light alone or retinal without blue light had no effect on cells.

The researcher found that a molecule called alpha tocopherol, a vitamin E derivative and a natural antioxidant in the eye and body, stops the cells from dying. However, as a person ages or the immune system is suppressed, people lose the ability to fight against the attack by retinal and blue light.

The lab currently is measuring light coming from television, cell phone and tablet screens to get a better understanding of how the cells in the eyes respond to everyday blue light exposure.

“If you look at the amount of light coming out of your cell phone, it’s not great but it seems tolerable,” said Dr. John Payton, visiting assistant professor in the UT Department of Chemistry and Biochemistry. “Some cell phone companies are adding blue-light filters to the screens, and I think that is a good idea.”

To protect your eyes from blue light, Karunarathne advises to wear sunglasses that can filter both UV and blue light outside and avoid looking at cell phones or tablets in the dark.

Karunarathne added: “By learning more about the mechanisms of blindness in search of a method to intercept toxic reactions caused by the combination of retinal and blue light, we hope to find a way to protect the vision of children growing up in a high-tech world.”

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