Nadine Furtado is an assistant clinical professor at the University of Waterloo's School of Optometry and Vision Science.
Download the poster (.pdf), which was originally shared at American Academy of Optometry annual meeting, 2016.
Comparative Study Examining Various Approaches to Reducing Exposure to High-Energy Visible Light from Digital Devices
Nadine M. Furtado; Timothy H. Tsang; Derek Y. Ho
Purpose: To evaluate the effectiveness of various available methods to reduce exposure to high-energy visible (HEV) blue light emitted from digital screens.
Methods: The screen of a hand held digital device and a laptop monitor were used, and an identical white target (RGB: 255,255,255) was presented on the screens. The spectroradiometer PR-670 was used to acquire transmittance spectrum data, and photometric, colorimetric and color temperature measurements. Measuring distance was set at 16 inches from the target with a 0.5 degree aperture setting. Measurements were acquired using three different lens setups: no lens, a standard lens with anti-reflective coating, and a lens with blue-light blocking properties. Each lens was tested under five different screen brightness settings (0%, 25%, 50%, 75% and 100%) and two software settings (default, and either Night Shift© mode or f.lux© software).
Results: The peak wavelength measured on digital device screens was 448nm with a color temperature of 6900K. At maximum brightness, the lens with antireflective coating resulted in a 1% reduction in luminance while the blue-light blocking lens caused a 3-4% decrease. Night Shift© and f.lux© software decreased luminance by 29% and 39%, respectively, at maximum screen brightness settings. A shift in color temperature was measured for all HEV reducing methods, with f.lux© showing the greatest amount of shift from 6900K to 3550K. The greatest reduction in HEV was found by adjusting screen brightness to lower settings, followed by a moderate reduction by blue-light reducing software compared to blue-light filtering lenses.
Conclusion: Reduction of HEV blue light from digital devices can be achieved by dimming screen brightness, using applications to change screen colour temperature and wearing lenses with blue-light reducing coatings / filters. The greatest reduction in HEV light was achieved by adjustments to the screen brightness parameters.