| Summary: | 碩士 === 中山醫學大學 === 生物醫學科學學系碩士班 === 100 === Ocular tissue damage because of exposure to visible light has been demonstrated by the results of human and animal studies. The short-wavelength visible light between 430 nm to 500 nm（blue light）is especially associated with retina damage. Recently, new powerful sources and relatively inexpensive blue energy of LED（light emitting diodes）family lamps in home illumination are available. However, the retinal photoreceptor damage produced by the low-powered LED illumination was not addressed. The aim of this study is to investigate the effects of illumination source from the low-powered and the conscious spectrum source of LED family lamps on retina. In order to investigate the influence of low-powered LED illumination on retina, LED emission was examined in C57BL/6 mice and retinoblastoma Y79 cells. The LED light was analyzed from 300nm to 800nm using an UV-visible spectrophotometry. In vivo, young adult mice were assigned to expose to family LED light for 2hours every day ranging 2 to 4 weeks or light environment using LED family lamps for 39 weeks. At different times after light exposure, animals were sacrificed and eyeballs were dissected as cross-sections. To illustrate the relationship between LED exposure and cell death, the histopathology and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling（TUNEL）assay were applied. Morphological results showed that the photoreceptor layer is significantly reduced in thickness after 4 weeks of LED exposure 2hours every day or LED illuminated environment. After light exposure, the photoreceptor layer was significantly reduced in thickness and TUNEL-positive nuclei were detected in the photoreceptor layer. In vitro, the human retinoblastoma cell line Y79 was also irradiated with LED light ranging 1、2 to 4 days. Cultured cells were analyzed by morphology, immunocytochemistry, and Western blot analysis. The cell stage of Y79 cell was smaller than that of the control, and the apoptosis-like characteristic of nuclei condensation could be observed. Increased p53 and caspase-3 proteins were detected in Y79 cells after light exposure. This study provides important information regarding the efficacy and safety in animal models of LED light in family illumination.
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