Violet-Blue Light Photobiological Effect on Cultured Corneal and Pigment Retinal Cells

Artificial optical radiation, spanning from 100 nm to 1 mm, encompasses ultraviolet (UV) and infrared (IR) light. UV light is well known for its risks on the skin and eyes. Recently, there has been growing interest in light at 405 nm (violet-blue light, VBL) due to its antimicrobial properties and perceived safety for mammalian cells when administered in controlled amounts. This research delved into the impact of 405 nm VBL on corneal and retinal pigment epithelial cell cultures. ARPE-19 and corneal BCE C/D 1b cells were exposed to VBL for varying doses, according at different exposure times, to evaluate cell viability, oxidative stress levels and apoptotic indicators. A 3D printed prototype with 14 LEDs centred at 405 nm wavelength was used to ensure uniform distribution of light during exposure. Cell viability was assessed using the MTT assay, measurement of oxygen species (ROS) production was carried out, and Western blot analysis was employed to study catalase and SOD-1 expression and apoptotic marker activation. Exposure to 405 nm VBL for both term (3 h) and prolonged durations (9 h) led to a weak decrease in cell viability in ARPE-19 cells, whereas the effect on BCE C/D 1b cells was negligible. There was no increase in ROS production, with catalase and SOD-1 expression remaining stable, suggesting no pro-oxidative stress effects in these models. Moreover, no activation of caspase-3 and accumulation of cytochrome C were found. Based on our results, exposure to 405 nm light at regulated levels does not pose a threat to the viability of the tested cell lines and does not lead to oxidative stress and apoptosis under these conditions. These results suggest a favourable cytocompatibility profile for these specific ocular cell models, laying a foundation for further investigations into its ocular safety.