Abstract
Purpose :
In response to growing concern about the effect of blue light on ocular tissue, companies have created phone screen protectors to block blue light. We evaluate the efficacy of one blue light blocking screen protector on the intensity of blue light emitted from a smartphone at different distances, settings of contrast, and with the smartphone’s built-in night shift mode.
Methods :
Using a spectrometer, the intensity of light emitted at 450 nm from a smartphone was measured in a dark room and a room with ambient light. The averages of three measurements were taken at 15 cm, 20 cm, 25 cm, 30 cm, 33 cm, and 40 cm with and without the screen protector. Varying degrees of contrast and night shift functions were also compared with and without the screen protector at each distance. Results were analyzed using paired t-tests.
Results :
For all tested conditions, the intensity of blue light measured decreased with increased distance away from the spectrometer. With the phone at 33 cm (working distance away from the face), in a dark room and at 100% contrast, the intensity significantly decreased by 61.6% with the filter, 81.6% with night shift mode and 87.9% with both the filter and night shift mode (p-value <.05). At 33 cm, night shift mode was 20% more effective at decreasing the intensity than the filter in a dark room (p-value <.05). Conversely, the filter was 13.3% more effective in ambient light at 33 cm (p-value <.05).
Conclusions :
Both applying the screen protector and enabling night shift mode substantially but not fully decreased the intensity of blue light. Using full night shift was more effective than the filter in a dark room. Research on the effects of blue light emitted from smartphones on the health of the eye should continue to fully understand the benefit of screen protectors that block blue light.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.