Optical Archives - EMFSA https://www.emfsa.co.za/tag/optical/ Electromagnetic fields South Africa Mon, 04 Mar 2019 22:56:56 +0000 en-US hourly 1 https://wordpress.org/?v=7.0 https://www.emfsa.co.za/wp-content/uploads/2021/02/cropped-EMFSA_logo-fv-32x32.png Optical Archives - EMFSA https://www.emfsa.co.za/tag/optical/ 32 32 Blue light exacerbates and red light counteracts negative insults to retinal ganglion cells in situ and R28 cells in vitro. https://www.emfsa.co.za/research-and-studies/blue-light-exacerbates-and-red-light-counteracts-negative-insults-to-retinal-ganglion-cells-in-situ-and-r28-cells-in-vitro/ Mon, 04 Mar 2019 22:56:27 +0000 https://www.emfsa.co.za/?p=7579 Neurochem Int. 2019 Feb 27. pii: S0197-0186(18)30627-2. doi: 10.1016/j.neuint.2019.02.018. [Epub ahead of print] Abstract Neurones are dependent on their mitochondria to produce the necessary amounts of ATP for survival. Retinal ganglion cells (RGCs) have a particularly large number of mitochondria which-unlike neurones in the brain-are exposed to visual light of 400-850 nm. Here we demonstrate that short […]

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]]>  2019 Feb 27. pii: S0197-0186(18)30627-2. doi: 10.1016/j.neuint.2019.02.018. [Epub ahead of print]

Abstract

Neurones are dependent on their mitochondria to produce the necessary amounts of ATP for survival. Retinal ganglion cells (RGCs) have a particularly large number of mitochondria which-unlike neurones in the brain-are exposed to visual light of 400-850 nm. Here we demonstrate that short wavelength visual blue light negatively affects mitochondrial function, causing oxidative stress and decreased cell survival. In contrast, long wavelength red light enhances mitochondrial function to increase survival of cultured R28 cells and reduce the effects of blue light. Induction of retinal ischemia for 60 min in dark conditions caused a reduction in ATP levels accompanied by decreased RGC numbers in all areas of the retina. These effects were diminished when ischemia was induced with concomitant delivery of red light, and exacerbated when blue light was used. We conclude that while the levels of blue light that reach the human retina will be a fraction of those used in the present study, the chronic nature might, on a theoretical basis, be detrimental to RGC mitochondria which are already affected by conditions such as glaucoma. Our findings also show that exposing the retina to red light may be a therapeutic approach to supporting healthy mitochondrial functions as part of the treatment for retinal diseases in which these organelles are affected.

Copyright © 2019. Published by Elsevier Ltd.

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]]> Blue Light, Devices, Screens and Blindness https://www.emfsa.co.za/news/blue-light-devices-screens-and-blindness/ Sat, 11 Aug 2018 15:02:56 +0000 http://www.emfsa.co.za/?p=5654 Excerpts: 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,” Kasun Ratnayake, a PhD student researcher working in Karunarathne’s cellular photo chemistry […]

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Excerpts:

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,” Kasun Ratnayake, a PhD student researcher working in Karunarathne’s cellular photo chemistry group, said. “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.

“No activity is sparked with green, yellow or red light,” Karunarathne said. “The retinal-generated toxicity by blue light is universal. It can kill any cell type.”

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.

“That is when the real damage occurs,” Karunarathne said.

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,” Dr. John Payton, visiting assistant professor in the UT Department of Chemistry and Biochemistry, said. “Some cell phone companies are adding blue-light filters to the screens, and I think that is a good idea.”

“Every year more than two million new cases of age-related macular degeneration are reported in the United States,” Karunarathne said. “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.”

UT chemists discover how blue light speeds blindness

Blue light excited retinal intercepts cellular signaling https://www.nature.com/articles/s41598-018-28254-8

 

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