The blue light dose from white light emitting diodes (LEDs) and other white light sources.

PURPOSE

This study was carried out to determine if light emitting diodes (LEDs) represented a special case in exposing the retina to blue light, when compared with other methods of backlighting television and computer screens and with fluorescent tube lighting.

METHOD

The spectral distribution of light from computer and television screens (cathode ray tube, plasma screen, organic LEDs, and screens backlit by cold cathode tubes and/or LEDs), domestic type spotlights (LED and fluorescent tube) and objects in the outdoor sunlit environment were measured with a telespectroradiometer. The spectral data were analysed for the proportion of blue light and luminance. The results were also presented as time to reach the occupational safety limit, without regard to the normal 10 000 s time limit by which time there is no summation of exposure.

RESULTS

The amount of blue light in a source is essentially independent of the technology of the light source, but closely related to the correlated colour temperature.

CONCLUSIONS

Fluorescent lamps show essentially the same proportions of blue light and LEDs do not represent a special case, given the same correlated colour temperature. Blue-blocking lenses are no more needed with LED sources than with other screen illumination methods or with fluorescent lighting. There is no evidence base on which to recommend blue-blocking lenses for indoor applications.