Background: A project originally developed for NASA plant growth experiments in space demonstrating the Light-Emitting Diode (LED) could promote the wound healing. Further study showed that the LED's could protect cells by stimulating the basic energy processes in the mitochondria of each cell.
Objective: The purpose of this study was to assess the effects of 670 nm LED to protect the photoreceptor from the light-induced damage in a rodent model.
Methods: SD rats were randomly assigned to one of eight groups: untreated control group, the LED-treated control group, three light-induced damage groups, and three LED-protected groups. The rats were exposed to constant light for 3 h of different illuminations of 900, 1,800 and 2,700 lux, respectively. The LED treatment (50 mW) were done for 30 min, 3 h before the light damage and 0, 24 and 48 h after the light damage. Using the electroretinogram as a sensitive indicator of retinal function, and the histopathologic change was showed as a proof of the protective effect of LED treatment.
Results: The 900 lux illumination for 3 h did not cause damage to the retina of rats, however, the 1,800 lux illumination for 3 h caused significant damage to ONL of an approximate half retina, which caused the swing of ERG b wave to be 431 muV. With the LED protection: the damage of ONL was near 1/6 of retina, which was significantly reduced than the ones without LED protection (P < 0.01); and the swing of ERG b wave was recorded to be 1,011 muV, which was increased significantly than the ones without LED protection (P < 0.01). The illumination of 2,700 lux for 3 h caused severe damage to the rats' retinas and the LED could not protect them significantly in both of morphology and function (P > 0.05, P > 0.05).
Conclusions: 670 nm LED treatment has an evident protective effect on retinal cells against light-induced damage, which may be an innovative and non-invasive therapeutic approach to prevent or to delay age-related macular degeneration.