Effects of blue light-exposed retinal pigment epithelial cells on the process of ametropia

Exosomes derived from human umbilical cord blood mesenchymal stem cells protect against blue light-induced damage to retinal pigment epithelial cells by inhibiting FGF2 expression

Age-related macular degeneration (AMD) is a debilitating retinal disorder that may lead to progressive vision loss. One contributing factor to AMD pathogenesis is excessive blue light (BL) exposure. In this study, we investigated the therapeutic potential of exosomes derived from human umbilical cord blood mesenchymal stem cells (hUCMSC-EXs) in addressing BL-induced damage to ARPE-19 human retinal pigment epithelial (RPE) cells and explored the underlying mechanisms. Our findings revealed that BL exposure induced morphological alterations in ARPE-19 cells, accompanied by a time-dependent decline in cell viability, increased apoptosis, heightened oxidative stress, and inflammatory responses; however, hUCMSC-EXs dose-dependently mitigated BL-induced ARPE-19 cell damage. Interestingly, hUCMSC-EXs were found to suppress the upregulation of fibroblast growth factor 2 (FGF2) in BL-exposed ARPE-19 cells. Furthermore, FGF2 overexpression partially counteracted the inhibitory effects of hUCMSC-EXs on FGF2 expression and compromised the protective benefits of hUCMSC-EXs against BL-induced ARPE-19 cell damage. In conclusion, our results suggest that hUCMSC-EXs shield ARPE-19 cells from BL-induced harm by inhibiting FGF2 expression.

The role of vitamin K and its antagonist in the process of ferroptosis-damaged RPE-mediated CNV

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in people over the age of 55. AMD currently affects approximately 8% of the world's population, and the number is growing as the global population ages. Growing evidence suggests that pathological choroidal neovascularization (CNV) is often related to more severe and rapid vision loss and blindness associated with AMD. The typical clinical treatment is intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) agents. However, some patients do not respond well to this therapy, and the potential risks of long-term repeated injections cannot be ignored. Therefore, there is an urgent need to explore the specific mechanisms of CNV development and find new, safe, and effective treatments. In this study, our data indicate that ferroptotic damage of retinal pigment epithelium (RPE) and its induced VEGFA overexpression are critical promoting factors in the development of CNV. Vitamin K can mediate the protection of RPE cells from ferroptotic damage and regulate the expression of eIF2α-ATF4-VEGFA in a VKOR/FSP1-dependent manner, inhibiting new angiogenesis to alleviate CNV. On the contrary, vitamin K antagonists (VKA) represented by warfarin, can promote RPE ferroptotic damage and related vascular proliferation in mice and eventually aggravate CNV lesions. However, vitamin K still showed significant protective effects even in the presence of VKA. Due to its significant anti-ferroptosis and anti-neovascular effects, as well as its relative safety and convenience of use, vitamin K has excellent potential in the treatment of CNV and is expected to become a clinically effective and safe new CNV treatment strategy.

High correlated color temperature white light-emitting diodes disrupt refractive development in guinea pigs

Ubiquitous white light-emitting diodes (LEDs) possess optical properties that differ from those of natural light. This difference can impact visual perception and biological functions, thus potentially affecting eye health. Myopia, which leads to visual impairments and potentially irreversible vision loss or blindness, is the most prevalent refractive error worldwide. Ambient light has been found to be a significant factor in refractive development. The overlap between the commonly utilized of white LEDs and the rapid increase in the prevalence of myopia raises suspicions that white LEDs may represent hidden visual cues. To clarify the potential effects of white LEDs on refractive development, we exposed guinea pigs to different forms of artificial lighting over a period of eight weeks. We found that exposure to white LEDs with a high correlated color temperature (CCT) of approximately 5000 K can induce significant myopic shifts in guinea pigs, along with a decrease in collagen accumulation in the sclera. Additionally, this exposure was found to significantly reduce choroidal tissue thickness in guinea pigs. Our study findings indicate that high CCT white LEDs disrupt refractive development in guinea pigs. These results suggest that high CCT white LEDs might similarly affect refractive development in humans, highlighting the need for further clinical investigation.

Effects of blue light exposure on ocular parameters and choroidal blood perfusion in Guinea pig

PURPOSE

To investigate the impact of different duration of blue light exposure on ocular parameters and choroidal blood perfusion in guinea pigs with lens-induced myopia.

METHOD

Three-week-old Guinea pigs were randomly assigned to different light-environment groups. All groups were subjected to 12-h light/dark cycle. The control (NC) group was conditioned without intervention. While lens-induced myopia (LIM) groups had a -10D lens placed in the right eye and 0D in the left eye. The guinea pigs were exposed to increasing periods of blue-light (420 nm) environment for 3,6,9,12 h per day. Changes in refraction, axial length (AL), the radius of corneal curvature (CCR), choroidal thickness (ChT), and choroidal blood perfusion (ChBP)were measured in both LIM-eye and fellow-eye during the second and fourth week of LIM duration.

RESULTS

During the first two weeks of the experiment, blue light exposure raised ChBP and ChT, and the effect of suppressing myopia was proportional to the duration of blue light exposure. However, in the fourth week of the experiment, prolonged blue light (12BL) exposure led to a reduction in retinal thickness and the increase in ChT and ChBP ceased. Shorter blue light exposure had a better effect on myopia suppression, with all blue light groups statistically different from the LIM group.

CONCLUSION

Exposure to blue-light appears to have the potential to improve ChBP and ChT, thereby inhibiting the development of myopia. we speculate that blue-light inhibits the development of myopia for reasons other than longitudinal chromatic aberration (LCA). However,long-term exposure to blue-light may have adverse effects on ocular development. The next step is to investigate in depth the mechanisms by which the rational use of blue light regulates choroidal blood flow, offering new hope for the treatment of myopia.