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Emiliano Teran, Pablo De Gracia, Cristo-Manuel Yee-Rendon, Jesus Ortega-Salazar, Joel Molina-Reyes, Efraín Romo García; On the smartphone's light emission and its blue light contribution. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4040.
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© ARVO (1962-2015); The Authors (2016-present)
To measure the emission spectrum of smartphones to know the impact that could have on the human eye. This can give us a tool to evaluate the impact that these electronic devices can have in the diurnal cycles.
The light emission spectrum of 36 smartphones was evaluated using the integrating sphere method. The evaluated models include: five LG, nine Samsung, ten Motorola, five iPhone, three Huawei, two Lenovo, and one HTC phones. The power spectrum was measured using a white background on the cel phone at the maximum “brightness” setting for regular use. Only for iPhones, the night shift setting was used because the remaining cel phones did not have this feature in its current Android version (≤6.0). T-test was used to obtain the average at the peak’s wavelength of the spectrums.
When in the regular mode, the power spectra of the 35 smartphones resembled a White LED source, showing three characteristic peaks at about 449.09±2.98, 545.23±6217, and 603.43±4.86 nm. For almost all of them the blue peak (~450nm) had twice as much power as the yellow (~545nm) and red (~603nm) peaks in the regular mode. It should be noted that there is no contribution of ultraviolet light, nor infrared. These regions are practically null compared to the three emission peaks in the visible. The power spectrum of the iPhones with the night shift setting had a 80% reduction in the power of the blue peak and an 80% increase in the red peak.
The night mode of the IPhones can have a beneficial impact in the melanopsin-expressing photoreceptor cells that drive the diurnal cycle. The rationale is that the “night light” settings (sometimes called “filters”) are meant to be beneficial to the diurnal cycle by reducing the inappropriate stimulation of the melanopsin receptors (some of which are retinal ganglion cells) with blue light at night. Due that smartphones do not emit ultraviolet light or infrared, strategies to protect the eyes must focus on their emission peaks.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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