High-energy visible light

In ophthalmology, high-energy visible light (HEV light) is high-frequency light in the violet/blue band from 380 to 530 nm in the visible spectrum.Dykas, Carol. " [http://www.2020mag.com/CE/TabViewTest/tabid/92/LessonId/3127/Default.aspx How to Protect Patients from Harmful Sunlight.] " www.2020mag.com. June, 2004.] HEV light has been implicated as a cause of age-related macular degeneration. [Glazer-Hockstein C, Dunaief JL. "Could blue light-blocking lenses decrease the risk of age-related macular degeneration?" "Retina." 2006 Jan;26(1):1-4. PMID 16395131] [Margrain TH, Boulton M, Marshall J, Sliney DH. "Do blue light filters confer protection against age-related macular degeneration?" "Prog Retin Eye Res." 2004 Sep;23(5):523-31. PMID 15302349]

Some sunglasses are now designed specifically to block HEV.

Blue-light hazard

Blue-light hazard is defined as the potential for a photochemical induced retinal injury resulting from radiation exposure at wavelengths primarily between 400 nm and 500 nm, [American National Standard Institute/ Illuminating Engineering Society of North America. “ANSI/IESNA RP-27.1-05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems – General Requirements.” Illuminating Engineering Society of North America Web Store 10 June. 2007 .] . The mechanisms for photochemical induced retinal injury are caused by the absorption of light by photoreceptors 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.” [(Williams TP, Howell WL. Action spectrum of retinal light-damage in albino rats. Invest Ophthalmol Vis Sci 1983;24:285–7.] [Pautler EL, Morita M, Beezley D. Hemoprotein(s) mediate blue light damage in the retinal pigment epithelium. Photochem Photobiol 1990;51:599–605.] Absorption of blue light, however, has been shown to cause a reversal of the process where cells become unbleached and responsive again to light before it is ready. This greatly increases the potential for oxidative damage [Grimm C, et al. Rhodopsin-Mediated Blue-Light Dam age to the rat Retina: Effect of Photoreversal of Bleaching. Invest Ophthalmol Vis Sci 2001 Feb;42(2):497-50.] . By this mechanism, some biological tissues such as skin, the lens of the eye, and in particular the retina may show irreversible changes induced by prolonged exposure to moderate levels of UV radiation and short-wavelength light.

References

External links

* [http://www.revoptom.com/index.asp?ArticleType=SiteSpec&page=body/transitions/transitions.htm The Effects of Visible Light and UVR on the Visual System - Review of Optometry]
* [http://www.mdsupport.org/library/hazard.html Artificial Lighting and the Blue Light Hazard (The Facts About Lighting and Vision)] MD Support Online Library