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Shang, Y. - M., Wang, G. - S., Sliney, D., Yang, C. - H., & Lee, L. - L. (2014). White light-emitting diodes (LEDs) at domestic lighting levels and retinal injury in a rat model. Environ Health Perspect, 122(3), 269–276.
Abstract: BACKGROUND: Light-emitting diodes (LEDs) deliver higher levels of blue light to the retina than do conventional domestic light sources. Chronic exposure to high-intensity light (2,000-10,000 lux) has previously been found to result in light-induced retinal injury, but chronic exposure to relatively low-intensity (750 lux) light has not been previously assessed with LEDs in a rodent model. OBJECTIVE: We examined LED-induced retinal neuronal cell damage in the Sprague-Dawley rat using functional, histological, and biochemical measurements. METHODS: We used blue LEDs (460 nm) and full-spectrum white LEDs, coupled with matching compact fluorescent lights, for exposures. Pathological examinations included electroretinogram, hematoxylin and eosin (H&E) staining, immunohistochemistry (IHC), and transmission electron microscopy (TEM). We also measured free radical production in the retina to determine the oxidative stress level. RESULTS: H&E staining and TEM revealed apoptosis and necrosis of photoreceptors, which indicated blue-light induced photochemical injury of the retina. Free radical production in the retina was increased in LED-exposed groups. IHC staining demonstrated that oxidative stress was associated with retinal injury. Although we found serious retinal light injury in LED groups, the compact fluorescent lamp (CFL) groups showed moderate to mild injury. CONCLUSION: Our results raise questions about adverse effects on the retina from chronic exposure to LED light compared with other light sources that have less blue light. Thus, we suggest a precautionary approach with regard to the use of blue-rich “white” LEDs for general lighting. CITATION: Shang YM, Wang GS, Sliney D, Yang CH, Lee LL. 2014. White light-emitting diodes (LEDs) at domestic lighting levels and retinal injury in a rat model. Environ Health Perspect 122:269-276; http://dx.doi.org/10.1289/ehp.1307294.
Keywords: LED; light emitting diode; lighting; retina; Eye Diseases; blue light; Blue-rich light sources
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Tosini, G., Ferguson, I., & Tubota, K. (2016). Effects of blue light on the circadian system and eye physiology. Mol Vis, 22, 61–72.
Abstract: Light-emitting diodes (LEDs) have been used to provide illumination in industrial and commercial environments. LEDs are also used in TVs, computers, smart phones, and tablets. Although the light emitted by most LEDs appears white, LEDs have peak emission in the blue light range (400–490 nm). The accumulating experimental evidence has indicated that exposure to blue light can affect many physiologic functions, and it can be used to treat circadian and sleep dysfunctions. However, blue light can also induce photoreceptor damage. Thus, it is important to consider the spectral output of LED-based light sources to minimize the danger that may be associated with blue light exposure. In this review, we summarize the current knowledge of the effects of blue light on the regulation of physiologic functions and the possible effects of blue light exposure on ocular health.
Keywords: Vision; blue light; Circadian Rhythm; eye; physiology
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Walker, C. E., & Pompea, S. M. (2011). National education program for energy efficient illumination engineering. Proceedings of SPIE Eco-Photonics 2011, Strasbourg, France, March 2011., 8065, 80650Q–1.
Abstract: About one-third of outdoor lighting escapes unused into the sky, wasting energy and causing sky glow. Because of excessive sky glow around astronomical facilities, the National Optical Astronomy Observatory has a strong motivation to lead light pollution education efforts. While our original motivation of preserving the dark skies near observatories is still important, energy conservation is a critical problem that needs to be addressed nationwide. To address this problem we have created an extensive educational program on understanding and measuring light pollution. A set of four learning experiences introduces school students at all grade levels to basic energy-responsive illumination engineering design principles that can minimize light pollution. We created and utilize the GLOBE at Night citizen science light pollution assessment campaign as a cornerstone activity. We also utilize educational activities on light shielding that are introduced through a teaching kit. These two components provide vocabulary, concepts, and visual illustrations of the causes of light pollution. The third, more advanced component is the school outdoor lighting audit, which has students perform an audit and produce a revised master plan for compliant lighting. These learning experiences provide an integrated learning unit that is highly adaptable for U.S. and international education efforts in this area.
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Warrant, E. (2004). Vision in the dimmest habitats on earth. J Comp Physiol A Neuroethol Sens Neural Behav Physiol, 190(10), 765–789.
Abstract: A very large proportion of the world's animal species are active in dim light, either under the cover of night or in the depths of the sea. The worlds they see can be dim and extended, with light reaching the eyes from all directions at once, or they can be composed of bright point sources, like the multitudes of stars seen in a clear night sky or the rare sparks of bioluminescence that are visible in the deep sea. The eye designs of nocturnal and deep-sea animals have evolved in response to these two very different types of habitats, being optimised for maximum sensitivity to extended scenes, or to point sources, or to both. After describing the many visual adaptations that have evolved across the animal kingdom for maximising sensitivity to extended and point-source scenes, I then use case studies from the recent literature to show how these adaptations have endowed nocturnal animals with excellent vision. Nocturnal animals can see colour and negotiate dimly illuminated obstacles during flight. They can also navigate using learned terrestrial landmarks, the constellations of stars or the dim pattern of polarised light formed around the moon. The conclusion from these studies is clear: nocturnal habitats are just as rich in visual details as diurnal habitats are, and nocturnal animals have evolved visual systems capable of exploiting them. The same is certainly true of deep-sea animals, as future research will no doubt reveal.
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