Mechanism of action of blue light stimulation of the blind spot in progressive myopia

Purpose: The beneficial effects of time spent outdoors and the seasonal increase of progression in winter emphasize the major role of daylight in myopia. Based upon the patho­physiology of myopia and the physiological effects of daylight, the mechanism of action of a targeted stimulation of melanopsin by blue light at the blind spot for the treatment of progressive myopia is investigated.

Material and Methods: The manuscript is a subjective review of the mechanism of action of blue light stimulation at the blind spot for the treatment of progressive myopia. The literature search in PubMed covered a period from 1980 through 2023.

Results: Blue light stimulation at the blind spot bases upon the clinical experience that daylight protects from the development of progressive myopia. Parameters and site of light stimulation are mainly defined by the photopigment melanopsin, that is sensitive to blue light and localized on intrinsically photosensitive, retinal ganglion cells (ipRGC) whose axons converge to the blind spot. The blind spot as stimulation site provides on the one hand the opportunity to activate the vast majority of ipRGC and hence dopaminergic amacrine cells, and on the other hand avoids additional involvement of rods and cones which may exert inhibitory effects on dopamine release. Furthermore, the proposed dopaminergic and potentially antimyopic effect can be applied invisibly to the patient.

Conclusion: Preclinical and human experimental studies indicate that after a short-term blue light stimulation the choroidal thickness transiently increases and the axial length of the eye decreases. These temporal changes of clinically relevant biomarkers after short-term blue light stimulation suggest potential antimyopic effects which are investigated in current clinical trials in children.