Abstract
Purpose:
Recently, our eyes are exposured to light emitting diode (LED) light of video display terminal (VDT) equipped with a liquid crystal display, such as television, personal computer, and smart phone. These VDT include large proportion of blue light that is harmful to eyes. Although blue light is harmful to eyes, it has not revealed that how blue LED light affects our eyes. Our purpose is to show the mechanism of photoreceptor damage induced by blue LED light.
Methods:
Cultured mouse cone photoreceptor derived cells (661W) were exposed to blue, white, or green LED light (0.38 mW/cm2) for comparison of cytotoxicity. We investigated the effect of N-acetylcystein (NAC), an antioxidant, against blue LED light exposure using tetrazolium salt (WST-8) assay, nuclear staining, measurement of reactive oxigen species (ROS), and Western blotting for nuclear factor-kappaB (NF-κB), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK). In immunostaining, the localization of cone photoreceptor specific protein, short-wavelength opsins (S-opsin) were observed in each LED light exposed cells.
Results:
The blue LED light irradiation induced severe photoreceptor cell damage due to large ROS production, activation of NF-κB, phosphorylation of p38 MAPK, and downregulation of ERK phosphorylation. Moreover, the aggregation of S-opsin was observed in blue and white LED light exposed cells, and the ratio of cells observed the aggregation of S-opsin was significantly increased in blue LED light exposed cells. On the other hand, green LED light did not induce the aggregation of S-opsin. NAC protected cell damage through inhibition of ROS production and it inhibited NF-κB activation, and caspase 3/7 activation.
Conclusions:
Our study demonstrated that blue LED light-induced photoreceptor damage was worse than those of white and green LED light in unified energy. So, it was suggested that this cell damage was wavelength-dependent and energy-independent. Additionally, an antioxidant has protective effect against blue LED light-induced photoreceptor cell degeneration.
Keywords: 412 age-related macular degeneration •
648 photoreceptors