Light-emitting-diode induced retinal damage and its wavelength dependency .

Aim: To examine light-emitting-diode (LED)-induced retinal neuronal cell damage and its wavelength-driven pathogenic mechanisms.

Methods: Sprague-Dawley rats were exposed to blue LEDs (460 nm), green LEDs (530 nm), and red LEDs (620 nm). Electroretinography (ERG), Hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunohistochemical (IHC) staining, Western blotting (WB) and the detection of superoxide anion (O·), hydrogen peroxide (HO), total iron, and ferric (Fe) levels were applied.

Results: ERG results showed the blue LED group induced more functional damage than that of green or red LED groups. H&E staining, TUNEL, IHC, and TEM revealed apoptosis and necrosis of photoreceptors and RPE, which indicated blue LED also induced more photochemical injury. Free radical production and iron-related molecular marker expressions demonstrated that oxidative stress and iron-overload were associated with retinal injury. WB assays correspondingly showed that defense gene expression was up-regulated after the LED light exposure with a wavelength dependency.

Conclusion: The study results indicate that LED blue-light exposure poses a great risk of retinal injury in awake, task-oriented rod-dominant animals. The wavelength-dependent effect should be considered carefully when switching to LED lighting applications.