Abstract
PurposeTo investigate the influence of overexposure to light emitting diode (LED)-derived light with various wavelengths on mouse ocular surface.MethodsLEDs with various wavelengths were used to irradiate C57BL/6 mice at an energy dose of 50 J/cm2, twice a day, for 10 consecutive days. The red, green, and blue groups represented wavelengths of 630 nm, 525 nm, and 410 nm, respectively. The untouched group (UT) was not exposed to LED light and served as the untreated control. Tear volume, tear film break-up time (TBUT), and corneal fluorescein staining scores were measured on days 1, 3, 5, 7, and 10. Levels of interferon (IFN)-γ, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α were measured in the cornea and conjunctiva using a multiplex immunobead assay at day 10. Levels of malondialdehyde (MDA) were measured with an enzyme-linked immunosorbent assay. Flow cytometry, 2’7’-dichlorofluorescein diacetate (DCF-DA) assay, histologic analysis, immunohistochemistry with 4-hydroxynonenal, and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining were also performed.ResultsTBUT of the blue group showed significant decreases at days 7 and 10, compared with the UT and red groups. Corneal fluorescein staining scores significantly increased in the blue group when compared with UT, red, and green groups at days 5, 7, and 10. A significant increase in the corneal levels of IL-1β and IL-6 was observed in the blue group, compared with the other groups. The blue group showed significantly increased reactive oxygen species production in the DCF-DA assay and increased inflammatory T cells in the flow cytometry. A significantly increased TUNEL positive cells was identified in the blue group.ConclusionsOverexposure to blue light with short wavelengths can induce oxidative damage and apoptosis to the cornea, which may manifest as increased ocular surface inflammation and resultant dry eye.
Highlights
A light emitting diode (LED) is a complex semiconductor that emits narrow-spectrum light when a suitable energy is supplied to the leads
Corneal fluorescein staining scores significantly increased in the blue group when compared with untouched group (UT), red, and green groups at days 5, 7, and 10
A significant increase in the corneal levels of IL-1β and IL-6 was observed in the blue group, compared with the other groups
Summary
A light emitting diode (LED) is a complex semiconductor that emits narrow-spectrum light when a suitable energy is supplied to the leads. It has been developed as an alternative option to replace traditional light sources, and is increasingly used as a lighting component in various electrical appliances, such as televisions, personal computers, and smart phones. LEDs are known to emit quite a large amount of blue light [1,2,3]. Blue light has been known to cause photoreceptor cell and retinal pigment epithelial cell (RPE) damage through excessive reactive oxygen species (ROS) production
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