Biological effects of high-energy visible light: Difference between revisions

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Line 4: ==Blue-light hazard== '''Blue-light hazard''' is defined as the potential for a [[photochemical]]-induced retinal injury resulting from electromagnetic [[Non-ionizing radiation\|radiation exposure]] at wavelengths primarily between 400 and {{nowrap\|450 nm.}} This study has not been done in humans, only inconclusively in some rodent, primate, and in vitro studies.<ref>{{Cite book\|publisher=American National Standard Institute/ Illuminating Engineering Society of North America\|title=ANSI/IESNA RP-27.1-05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems – General Requirements\|date=10 June 2007 \|url=https://www.iesna.org/shop/\|deadurl=yes\|archiveurl=https://web.archive.org/web/20070815023605/https://www.iesna.org/shop/\|archivedate=15 August 2007\|df=}}</ref> The mechanisms for photochemical induced retinal injury are caused by the absorption of light by [[Photoreceptor cell\|photoreceptor]]s in the eye. Under normal conditions when light hits a photoreceptor, the cell bleaches and becomes useless until it has recovered through a metabolic process called the [[visual cycle]].<ref>{{cite journal\|vauthors=Williams TP, Howell WL \|title=Action spectrum of retinal light-damage in albino rats \|journal=Invest. Ophthalmol. Vis. Sci. \|volume=24 \|issue=3 \|pages=285–7 \|date=March 1983 \|pmid=6832904 \|url=http://www.iovs.org/cgi/pmidlookup?view=long&pmid=6832904 \|archive-url=https://archive.is/20120525164412/http://www.iovs.org/cgi/pmidlookup?view=long&pmid=6832904 \|dead-url=yes \|archive-date=2012-05-25 }}</ref><ref>{{cite journal \|doi=10.1111/j.1751-1097.1990.tb01972.x \|vauthors=Pautler EL, Morita M, Beezley D \|title=Hemoprotein(s) mediate blue light damage in the retinal pigment epithelium \|journal=Photochem. Photobiol. \|volume=51 \|issue=5 \|pages=599–605 \|date=May 1990 \|pmid=2367557 \|url=http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0031-8655&date=1990&volume=51&issue=5&spage=599}}</ref> Absorption of blue light, however, has been shown in rats and a susceptible strain of mice to cause a reversal of the process where cells become unbleached and responsive again to light before they are ready. At wavelengths of blue light below 430 nm this greatly increases the potential for oxidative damage.<ref>{{cite journal\|vauthors=Grimm C, Wenzel A, Williams T, Rol P, Hafezi F, Remy C \|title=Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching \|journal=Invest. Ophthalmol. Vis. Sci. \|volume=42 \|issue=2 \|pages=497–505 \|date=February 2001 \|pmid=11157889 \|url=http://www.iovs.org/cgi/pmidlookup?view=long&pmid=11157889 \|archive-url=https://archive.is/20120525164413/http://www.iovs.org/cgi/pmidlookup?view=long&pmid=11157889 \|dead-url=yes \|archive-date=2012-05-25 }}</ref> For blue-light circadian therapy, harm is minimized by employing blue light at the near-green end of the blue spectrum. "1-2 min of 408 nm and 25 minutes of 430 nm are sufficient to cause irreversible death of photoreceptors and lesions of the retinal pigment epithelium. ... The action spectrum of light-sensitive retinal ganglion cells was found to peak at approximately 450 nm, a range with lower damage potential, yet not completely outside the damaging range."<ref>{{cite journal\|author=Remy C\|title=Blue Light and the Retina: Good and Bad?\|journal=Soc Light Treatment Biol Rhythms\|volume=Abstracts 2005, 17:46}}</ref> A 2014 study found that [[LED]]s cause retinal damage even in settings where they are used indirectly, such as household light bulbs.<ref>{{Cite journal\|first=Tim \|last=Lougheed \|title=Hidden Blue Hazard? LED Lighting and Retinal Damage in Rats \|date=March 2014 \|journal=Environmental Health Perspectives \|volume=122 \|issue=3 \|page=A81 \|DOI=10.1289/ehp.122-A81 \|pmid=24583823 \|pmc=3948029}}</ref>