Abstract
Purpose :
Laser red light therapy has emerged as a myopia treatment in China. While the mechanism of this therapy in myopia remains unknown, red light has been shown to improve oxygenation in other tissues, such as skin. Recent studies indicate that hypoxia is a major contributor to myopia development, with evidence from animal models suggesting that choroidal thinning and reduced blood perfusion lead to myopic shifts in refraction. This study aimed to determine whether 5 minutes of red light exposure induces changes in the vascular structures of the human eye.
Methods :
Healthy adults ages 18-40 years (n=15) each participated in four lab visits in a randomized order, two red light and two control conditions, in the morning and in the evening. For red light conditions, participants underwent 5 minutes of red light exposure (λ= 626 nm, irradiance 0.8 mW/cm2, Colordome, Espion, Diagonosys LLC). For control conditions, participants were exposed to standard indoor lighting (approximately 400 lux). Biometry, optical coherence tomography (OCT), and OCT-angiography (OCTA) imaging were performed for the right eye at baseline and 5, 30, and 60 minutes after exposure. Changes in axial length and retinal perfusion density for the superficial and deep vascular plexi were compared between the control and the red light conditions at morning and evening and assessed with two-way repeated measures ANOVAs.
Results :
The mean age of participants was 28±5 years (4M:11F). Baseline axial length was 24.07±0.92 mm, and spherical equivalent refraction was -0.91±1.86 D. There were no differences in axial length between morning red light and control conditions at 5, 30, or 60 minutes in the morning (P>.05 for all) or evening (P>.05 for all). For the central 1 mm radius, there were no differences in perfusion densities of the superficial vascular complex or deep vascular complex between morning red light and control conditions at 5, 30, or 60 minutes in the morning (P>.05 for all) or evening (P>.05 for all).
Conclusions :
Five minutes of diffuse LED-based red light exposure did not induce significant changes in axial length or retinal perfusion density for the superficial and deep vascular plexi. Future studies using laser-based red light may reveal significant effects on retinal vascular perfusion, which may help determine the mechanism of red light therapy in myopia.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.