The French Agency for Food, Environmental and Occupational Health & Safety (ANSES) said that its findings confirm earlier concerns that "exposure to an intense and powerful [LED] light is 'photo-toxic' and can lead to irreversible loss of retinal cells and diminished sharpness of vision”.
The agency recommended in a 400-page report that the maximum limit for acute exposure be revised, even if such levels are rarely met in a home or work environments.
The report distinguished between acute exposure of high-intensity LED light, and "chronic exposure" to lower intensity sources.
While less dangerous, even chronic exposure can "accelerate the ageing of retinal tissue, contributing to a decline in visual acuity and certain degenerative diseases such as age-related macular degeneration", the agency concluded.
LED uses only a fifth of the electricity needed for an incandescent bulb of equal brightness.
The world's leading LED light-bulb makers are GE Lighting, Osram and Philips.
The underlying technology for producing a white light combines a short wavelength LED such as blue or ultraviolet with a yellow phosphor coating — the whiter or "colder" the light, the higher the proportion of blue in the spectrum.
LED cellphone, tablet and laptop screens do not pose a risk of eye damage because their luminosity is very low compared to other types of lighting, Francine Behar-Cohen, an ophthalmologist and head of the expert group that conducted the review, told journalists.
But these back-lit devices -- especially when they are used at night or in a dark setting -- can "disturb biological rhythms, and thus sleep patterns", the agency cautioned.
Children and adolescents are particularly susceptible to such disruptions, the ANSES reports noted.
A stroboscopic effect in some LED lights -- provoked by tiny fluctuations in the electric current -- can induce "headaches, visual fatigue and a higher risk of accidents", the report said.
For indoor lighting, ANSES recommended buying "warm white" LED lighting, limiting exposure to LED sources with a high concentration of blue light, and avoiding LED screens before bedtime.
Finally, the agency cast doubt on the efficacy of some "anti-blue light" filters and sunglasses.