Optical chemistry research at the University of Toledo (UT) in Ohio has shown how blue light from digital devices and the sun can cause age-related macular degeneration. The study has uncovered the process by which blue light turns vital molecules in the eye’s retina into cell killers. That process leads to AMD.
“We are being exposed to blue light continuously, and the eye’s cornea and lens cannot block or reflect it,” says 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.”
The study, published this month in Scientific Reports states in its abstract:
“Using live cell imaging and optogenetic signaling control, we uncovered that blue light-excited ATR and 11CR irreversibly change/distort plasma membrane (PM) bound phospholipid; phosphatidylinositol 4,5 bisphosphate (PIP2) and disrupt its function. This distortion in PIP2 was independent of visual or non-visual G-protein coupled receptor activation. The change in PIP2 was followed by an increase in the cytosolic calcium, excessive cell shape change, and cell death…. These findings suggest that retinal exerts light sensitivity to both photoreceptor and non-photoreceptor cells, and intercepts crucial signaling events, altering the cellular fate.”
According to a blog post about the research on the UT website, the study found that blue light exposure causes the retinal molecules—those molecules on the photoreceptor cells that sense light and trigger the signaling to the brain— 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,” Kasun Ratnayake, a PhD student researcher working in Karunarathne’s cellular photo chemistry group, says in the blog post. “Photoreceptor cells do not regenerate in the eye. When they’re dead, they’re dead for good.”
As part of the study, 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.
“No activity is sparked with green, yellow or red light,” Karunarathne says. “The retinal-generated toxicity by blue light is universal. It can kill any cell type.”
“Every year more than two million new cases of age-related macular degeneration are reported in the United States,” Karunarathne says. “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.”
The lab currently is measuring light coming from television, cell phone, and tablet screens to better understand of how the cells in the eyes respond to everyday blue light exposure.