High-energy visible light

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In ophthalmology, high-energy visible light (HEV light) is high-frequency light in the violet/blue band from 400 to 500 nm in the visible spectrum.[1] HEV light has been implicated as a cause of age-related macular degeneration.[2][3]

Some sunglasses are now designed specifically to block HEV.[1]

Blue-light hazard[edit]

Blue-light hazard is defined as the potential for a photochemical induced retinal injury resulting from electromagnetic radiation exposure at wavelengths primarily between 400 - 500 nm. This has not been shown to occur in humans, only inconclusively in some rodent and primate studies.[4] 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.[5][6]

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.[7] 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 470-480 nm, a range with lower damage potential, yet not completely outside the damaging range."[8]

See also[edit]

References[edit]

  1. ^ a b Dykas, Carol (June 2004). "How to Protect Patients from Harmful Sunlight". www.2020mag.com. 
  2. ^ Glazer-Hockstein C, Dunaief JL (January 2006). "Could blue light-blocking lenses decrease the risk of age-related macular degeneration?". Retina (Philadelphia, Pa.) 26 (1): 1–4. doi:10.1097/00006982-200601000-00001. PMID 16395131. 
  3. ^ Margrain TH, Boulton M, Marshall J, Sliney DH (September 2004). "Do blue light filters confer protection against age-related macular degeneration?". Prog Retin Eye Res 23 (5): 523–31. doi:10.1016/j.preteyeres.2004.05.001. PMID 15302349. 
  4. ^ ANSI/IESNA RP-27.1-05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems – General Requirements. American National Standard Institute/ Illuminating Engineering Society of North America. 10 June 2007. 
  5. ^ Williams TP, Howell WL (March 1983). "Action spectrum of retinal light-damage in albino rats". Invest. Ophthalmol. Vis. Sci. 24 (3): 285–7. PMID 6832904. 
  6. ^ Pautler EL, Morita M, Beezley D (May 1990). "Hemoprotein(s) mediate blue light damage in the retinal pigment epithelium". Photochem. Photobiol. 51 (5): 599–605. doi:10.1111/j.1751-1097.1990.tb01972.x. PMID 2367557. 
  7. ^ Grimm C, Wenzel A, Williams T, Rol P, Hafezi F, Remy C (February 2001). "Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching". Invest. Ophthalmol. Vis. Sci. 42 (2): 497–505. PMID 11157889. 
  8. ^ Remy C. "Blue Light and the Retina: Good and Bad?". Soc Light Treatment Biol Rhythms. Abstracts 2005, 17:46. 

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