Abstract
Purpose :
Blue light stimulation of melanopsin expressed on intrinsically photosensitive retinal ganglion cells (ipRGC) at the optic disc may affect ocular growth and myopia development. Acute changes of the clinically relevant biomarkers, choroidal thickness (ChT) and axial length (AxL), were observed in adult volunteers after a single blue light stimulation of the blind spot. This study investigated the influence of the time of day of blind spot stimulation on ChT and AxL changes in myopic and emmetropic children.
Methods :
Subfoveal ChT and AxL of 10 emmetropic and 10 myopic children (9 to 14 years) were measured with enhanced-depth imaging optical coherence tomography and ocular biometry. ChT and AxL were assessed before and up to one hour after a 1-min blind spot stimulation with flickering blue or red light. All 20 volunteers participated in two experimental days with blue or red light stimulation at 8 am and 5 pm in randomized order. A subgroup of 6 participants received additional light stimulation on both experimental days (blue, red) at 12 pm. Linear mixed models were performed to examine the main effects and interactions of wavelength, time, refractive error, and time of the day for ChT and AxL separately.
Results :
A significant main effect was observed for wavelength and its interaction with time (p<0.001) for ChT and AxL. A significant increase in subfoveal ChT was observed after the stimulation with blue compared to red light, increasing with time up to +6.2 µm vs -0.2 µm after 60 min, respectively. Consistent AxL changes were observed 60 min after stimulation with blue or red light (-6.8 µm vs +1.2 µm). There was no significant main effect of time of the day and refractive error for ChT, but their interaction for AxL (p=0.01). No significant effect was observed at 12 pm.
Conclusions :
For the first time, this study has shown that blue light stimulation of the blind spot induces thickening of the choroid and AxL’s shortening in children, independent of refractive error and time of the day. This suggests that blue light stimulation at 8 am or 5 pm may provide similar therapeutic benefits for myopia control. Since application of blue light stimulation only induced small ChT changes in myopic adults, these results show that myopic children may have a greater susceptibility to blue light stimulation than myopic adults.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.