Thèse de doctorat en Neurosciences
Sous la direction de Francine Béhar-Cohen.
Soutenue le 30-11-2015
à Sorbonne Paris Cité , dans le cadre de École doctorale Médicament, toxicologie, chimie, imageries (Paris) , en partenariat avec Université Paris Descartes (1970-2019) (établissement de préparation) .
Le président du jury était Jean-Louis Bourges.
Evaluation de la toxicité oculaire des systèmes d'éclairage à LED
Pas de résumé
The aim of the study was to evaluate in controlled retinal risk LED lighting conditions compared to other common household lighting such as CCFL or CFL, in standard lighting conditions, on different animal species pigmented and non-pigmented. At first, we characterized the conditions of adaptation before enlightenment. We found that housing conditions before the light exposure is a source of artifact. Indeed, the location of the cages in a ventilated cabinet and the period before stalling before illumination generates a variable response to retinal light toxicity. Then, we tested the relative sensitivity of the albino strains and pigmented. After 3 weeks of stabulation, the animals were exposed for 24 hours to cold white LED at a luminance of 6000 lux, with dilation of pupils, and the retinas were examined in a week. In these extreme illumination conditions, retinas showed a significant loss of photoreceptors in superior retina, not only in albino animals, but also in pigmented animals. In another experiment, we tested different luminance in cages provided for this purpose. We have used as control a compact fluorescent lighting at 500 lux, with a homogeneous on the floor of the cage. An illumination of 24 hours dilation was performed after the time of dark adaptation. A luminance of 500 lux is a classic condition of a good visual quality domestic lighting. Unlike a compact fluorescent lighting at 500 lux, white LEDs result in a significant loss of photoreceptor nuclei of retinal pigmented rats (LE) 500 lux with an increasing toxicity in function of the luminance of the LED lighting. Finally, to assess the effects prolonged exposure we exposed the rats for one week or one month, but in alternating illumination only during the day, and without dilated pupils (day / night cycle 12h / 12h, no dilated pupils) with LED different spectra. We have compared these lighting conditions to a compact fluorescent lighting at 500 lux and non-illuminated rats. After one week, only albino rats showed a loss of photoreceptors and only after exposure to blue LEDs. These results show that the blue LEDs are more toxic than the white LEDs confirming the effects of short wavelengths. After 1 month of illumination, a significant loss of photoreceptors is observed in the retinas of non-pigmented rats, not only with the blue LEDs, but also with green LEDs and cool white LEDs. An increase of the exposure time under standard conditions leads to a loss of photoreceptors accumulated suggesting a potentially toxic effect of LED light, not observed with a compact fluorescent lighting even luminance.