Abstract:Abstract Purpose: To investigate the effects of blue light exposure derived from light-emitting diodes (LEDs) on the human ocular surface. Methods: Thirty healthy volunteers were enrolled in this study. The ocular surface disease index (OSDI), tear secretion volume, non-invasive keratograph break-up time (NIBUT), and corneal sodium fluorescein staining were measured before and after close-range exposure to blue light emitted by LEDs. Concentrations of the oxidative stress markers hexanoyl lysine (HEL) and 4-hydroxy-2-nonenal (4-HNE) in the tear film were quantified by ELISA. All measurements were conducted at baseline and after 1 and 4 hours of exposure. Results: All parameters showed no significant differences at baseline. Compared with the baseline group, the OSDI scores significantly increased in both the group exposed to blue light via smartphone for 1 hour and the group exposed for 4 hours (P <0.01). The 4-hour group exhibited higher OSDI, fatigue, burning, and dryness scores than the other groups. The 4-hour group showed a significant reduction in NIBUT (P < 0.01). HEL concentrations were significantly increased in the 1-hour and 4-hour groups compared with the baseline group (P < 0.05). No statistically significant differences were observed in tear secretion, corneal fluorescence staining, or 4-HNE levels throughout the study. Conclusions: While minimizing excessive tear evaporation caused by prolonged inter-blink intervals during gazing and the accommodative-convergence load associated with near work, Close-range exposure to blue light emitted by LEDs from smartphones not only exacerbates subjective symptom indices such as OSDI but also destabilizes the tear film and elevates oxidative stress levels in tears. This may increase ocular surface oxidative stress, thereby contributing to potential risks of corneal oxidative damage, ocular surface inflammation, and dry eye. Keywords: Dry eye disease; Blue light
