Abstract
Purpose :
Blue light is an accelerating factor in retinal ageing and a contributing factor in age-related macular degeneration (AMD). We recently identified 415-455 nm as the most toxic band within the blue wavelengths for the retinal pigment epithelium (RPE) cells (Arnault et al., 2013) (Marie et al., ARVO 2015, 2016). We here investigated the in vitro photoprotective effect of optical filters designed to specifically block between 20 and 70% of this toxic band, including a so-called Smart Blue Filter. We compared their protection with broad filtering in the blue-violet and blue-green parts of visible light. We aimed at defining a blue-violet filtering rate allowing a significant photoprotection level by an aesthetic spectacle lens.
Methods :
Primary swine RPE cells were loaded with 20 µM of A2E, a major chromophore of lipofuscin, to mimic retinal ageing. Cells were then exposed during 18 hours to a purpose-made light device that delivered 1.8 mW/cm2 of daylight spectrum within the visible range 400-600 nm weighted by the eye media filtering. Filters were interposed between the retinal cells and the light source to evaluate their in vitro protection potency against light-induced cell damage. Apoptosis, accumulation of hydrogen peroxide (H2O2) and mitochondrial membrane potential (MMP) were measured at the end of light exposure or after a rest period.
Results :
In A2E-loaded RPE cells, mimicked-daylight at moderate irradiance level increased by 1.5 the apoptosis rate compared to cells maintained in darkness, increased by 4.5 the H2O2 accumulation and decreased by 60% the MMP. The 20% blue-violet filtering Smart Blue Filter was able to decrease by up to 40% cell apoptosis and by 25% H2O2 accumulation after light exposure. Cutting 70% of 415-455 nm while letting pass the other parts of blue light decreased by 60% and 70% respectively the H2O2 accumulation and the apoptosis. This in vitro photoprotection is closely comparable to the one conveyed by the usual dark-yellow filter.
Conclusions :
The results on selective filters versus the unselective one confirmed the major effect of the narrow band 415-455 nm and helped us to design a lens with adequate trade-off between aesthetics and significant in vitro photoprotection.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.