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Gyu Hyun Kim, Sun-Sook Paik, Hyung Il Kim, In-Beom Kim; Functional and morphological evaluation of a mouse model for the retinal degeneration induced by blue LED. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5426. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The video display terminals, such as televisions, computers, and smart phones, mainly use the light emitting diode (LED) and emit an considerable amount of blue light. Blue light can trigger production of reactive oxygen species (ROS), leading to photochemical damage which can cause retinal degeneration (RD). The present study was aimed to establish and evaluate RD model induced by blue LED in mice both functionally and morphologically.
Balb/c mice were dark adapted for 24 hours and placed in blue LED (430 - 490 nm) for 2 hours in the reflective cage with different light intensities (1000, 2000, 3000, and 6000 lux). Electroretinogram (ERG) recordings (N=6) were performed to evaluate the retinal function at several time points after blue LED exposure. For histological assessment, hematoxyline and eosin staining was carried out on each retina. In addition, immunohistochemistry with an antibody against 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative stress, was performed.
We first examined changes in a- and b-waves of ERG responses at 5 days after exposure of blue LED with different intensities. Both waves of ERG responses in amplitude were significantly reduced in proportion to the increase in light intensity (a-wave: p<0.05; b-wave: p<0.05), compared with those of control mice. Next, to examine the time-dependent RD pattern, ERG recording was conducted at 0, 1, 3, and 5 days in mice exposed to blue LED with fixed light intensity of 2000 lux. The ERG amplitude of a-waves showed significant reduction by 13, 65, 80, and 80%, respectively, when compared to that of normal a-waves. The b-wave amplitudes were about 32, 52, 70, and 76% of normal b-waves in response to scotopic light stimulus. Thus, all scotopic ERG components decreased in a time-dependent manner. Histologically, retinal thickness was decreased in both light intensity- and time-dependent manners. In addition, in mice exposed to blue LED, 8-OHdG immunoreactivity was increased in the outer plexiform layer where photoreceptors reside.
The present study demonstrates that blue LED light induces RD that progresses in both light intensity- and time-dependent manners. Functional reduction following RD correlates with histological changes. Thus, this in vivo mouse model appears to be suitable to evaluate the effects of new therapeutic agents before clinical trials.
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