Can we protect our eyes from harmful blue light without depriving them of physiologically necessary blue light?

Numerous studies have shown that regular exposure to light has harmful effects on our visual system and is therefore detrimental to our health.

But what is blue light?

Blue light" is the spectrum of visible light with a short wavelength, i.e. between 380 and 500 nm, which includes violet, indigo, blue and green. This spectrum of visible light exists in natural light (sunlight) and artificial light, particularly LED lamps. Today there are technical solutions that make it possible to buy ophthalmic lenses with a "blue filter", either incorporated into the anti-reflective treatment or incorporated into the lens material itself, which aims to reduce this toxic effect.

Is all blue light toxic and should it be filtered out?

The answer is no!

The spectrum of blue light between 465 and 495 nm (turquoise) is even essential and has a positive effect on our health [1]. It is the "good" blue light, also known as "chronobiological light", which regulates our circadian rhythm.

We all need to reset our body clock every day to be able to synchronise our biological rhythm. Our biological clock transmits to various parts of the body, such as the liver, muscles, heart and kidneys. All biological functions need to work at the right time. As our biological clock drives this specific rhythm, it ensures that certain functions are active at the right time.

Light acts on the retina through the action of specific cells - ganglion cells containing melanopsin - which are different from the cones and rods that are the photoreceptors used in vision. When these ganglion cells are activated by blue light, they transmit a nerve signal that runs along the optic nerve and, instead of activating visual structures in the brain, activates non-visual structures, such as our internal circadian clock. It is therefore exposure to light that resets our biological clock.

So which blue light is harmful to health?

The spectrum between 415 and 455 nm (blue-violet), with its peak at 435 nm, has been identified as inducing toxic reactive oxygen species that cause photochemical damage. This leads to death by apoptosis in the first stage of the retinal pigment epithelial cells and then of the photoreceptors. This slow process, in which damage accumulates over a lifetime, has been implicated in the pathogenesis of retinal degenerative diseases such as age-related macular degeneration (AMD). [2]
The fact that blue light is both beneficial and toxic poses an important challenge. Can we protect our eyes from harmful blue light without depriving them of physiologically necessary blue light? The solution cannot be to block/filter 100% the entire spectrum of blue light, something that, from a technical point of view, would even be relatively easy to achieve. The solution has to be to attenuate the harmful wavelengths. Thus, as there is only a reduction (and not a total blockage) of the transmission of only a narrow band of blue-violet light, our circadian rhythm remains regulated. In addition, excellent colour transmission and transparency are maintained, providing superior vision quality.

At Solutions Lenses you'll find this solution in the inBlue treatment. You can see catalogue and find out more details.

[1] Arnault E, Barrau C, Nanteau C, et al. Characterisation of the blue light toxicity spectrum on A2E-loaded RPE cells in sunlight normalized conditions. Poster presented at: Association for Research and Vision in Ophthlamology Annual Meeting; 2013 May 5-9; Seattle, WA.
[2] Hattar S, Liao HW, Takao M, Berson DM, Yau KW. Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity. Science. 2002 Feb 8;295(5557):1065-70.