Background: The usage of the light emitting diode (LED) has been increasingly applied in the illumination setting and electronic equipment. However, the effect of LED lights on the retina remains unclear. In this study, we observed and analyzed the impact of white LED lights at different intensities on the function and morphology of rat retinas.
Methods: Thirty-six Sprague-Dawley rats weighing 150–180 g were randomly divided into six groups (n=6 in each group) including a normal control (NC) group, 4 white LED groups at different light intensities (4,000, 6,000, 7,000, and 10,000 lux), and an ultraviolet B (UVB) lighting group (302 nm, 1,000 μw/cm2). After 24 hours of continuous illumination, full-field flash electroretinogram (FERG) and pathological examination were performed in each group.
Results: As revealed by FERG, the impairment of retinal function gradually worsened with the increase of LED light intensity. In contrast, the UVB group had the most severe retinal function impairment. Particularly, the functional damage of rod cells and inner nuclear layer cells was the main FERG finding in each group. In the NC group, the retina had typical morphologies featured by well-defined structures, clearly visible border between the inner and outer segments, and neatly arranged inner and outer nuclear layer cells. After 24 hours of illumination, the inner and outer parts of the retina in the 4,000 lux group were still neatly arranged, along with a clear border; however, the inner and outer nuclear layers were randomly arranged, and some irregular nuclei and cells were lost. The damage of the internal and external retinal segments and the internal and external nuclear layers became more evident in the 6,000 lux group, 7,000 lux group, and 10,000 lux group. The UVB group had a more obviously disordered arrangement of inner and outer nuclear layers and loss of cells.
Conclusions: Continuous exposure to white LED light can cause structural and functional damage to rat retinas, and such damage is related to the intensity of illumination. Therefore, the risk of retinal damage should be considered during LED illumination, and proper LED illumination intensity may help to maintain eye health.
