Blue and green light contained in white light contribute significantly to phototoxicity to the retina and induce an inflammatory reaction
In the study, albino rats were exposed to blue light (450 nm). At a dose of 0.2 J/cm², immune cells infiltrated the retina, indicating an inflammatory reaction. At a dose of 0.5 J/cm², the amount of damaged cells was up to 100 times higher than in the control group, and there was a loss of photoreceptors and changes in their morphology.
Exposure to white light (CCT 2700 K, 2 J/cm²) with 10% blue light caused 10 times more retinal damage than the same amount of blue light (0.2 J/cm²). This suggests that another spectral region plays a role in photochemical damage to the retina, as confirmed by the green light (507 nm) experiment.
The study shows that the combination of blue and green light in a white LED shows an increased phototoxic effect compared to the individual components.
Red light has the potential to attenuate the harmful effects of blue light and thus partially protect against photoreceptor death
The results show that red energy above 630 nm contained in white light has a protective effect against cell death or apoptosis in the retina. The red light alleviated the inflammatory reaction induced by the white light. It is therefore desirable that in artificial lighting used indoors, the red wavelengths present in sunlight are also sufficiently represented in the emitted light. However, they are absent in the spectral composition of the vast majority of conventional commercial luminaires.
Stricter standards for lighting indoors
The researchers conclude that the current regulations and limits for the safety of LED light sources in terms of potential damage to the retina from light with intense emissions in the blue region are not sufficiently stringent for indoor applications and need to be revised to take the characteristics of today’s predominant LED light sources into account. The phototoxicity threshold for white LEDs was significantly lower than the US standard for maximum permissible exposure, according to the research results.
The study therefore shows that:
- Blue light (below 450 nm) in white LED light stimulates an inflammatory reaction in the retina.
- Adding red energy (above 630 nm) to white LED light can compensate for these negative effects.
- To reduce the risk of eye damage, we should use luminaires with a balanced spectral composition and sufficient radiation in the red spectral region, mimicking the sun.
