SOLAR RADIATION & GLAUCOMA

 

There are some reports suggesting that solar radiation, especially ultraviolet (UV) radiation and blue light may play an important role in the causation of glaucoma.

Effect of UV radiation at different ages

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) defines several subgroups of ultraviolet or invisible radiation classified into UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm). Infrared (IR) radiation has also been subdivided into three groups depending on the wavelength: IRA (700-1400 nm), IRB (1400-3000 nm) and IRC (3000-10,000 nm). [1]

Although the exact mechanism of UV-light induced glaucomatous degeneration is not known, yet, there are certain pointers to its probable association.

Osborne et al. have shown that blue light, also called high-energy visible light, which has higher wavelength than UV light (450-490 nm),  adversely affects the mitochondria of retinal ganglion cells (RGCs). Moreover, there is evidence that the mitochondrial electron transport chain-related enzymes flavin and cytochrome-C oxidase are damaged by blue light, resulting in the generation of photochemical effects and reactive oxygen species (ROS). [2]

ROS are normally regulated by antioxidants, but in eyes deformed by ischemia or myopia, blue light leads to excessive production of ROS and mitochondrial DNA damage. Ultimately, this results in the loss of the visual field owing to a cascade of events leading to cell death. When the retina is exposed to blue light under ischemic conditions, it produces relatively low levels of ATP, the RGCs get damaged, and mitochondrial energy metabolism is inhibited. [3]

Apoptosis is induced when the apoptosis-inducing factor (AIF), which exists in the spaces between the mitochondrial membranes of retinal epithelial cells, splits into two molecules, gets activated, and enters the nucleus of the cell. In contrast, necroptosis is programmed necrosis within the cell, in which receptor-interacting protein kinase 1 (RIP1) and receptor-interacting protein kinase 3 (RIP3) form a complex and perform their functions. In addition to activating AIF in retinal cells, blue light also stimulates RIP1 and RIP3 activation in RGCs. [3]

Osborne et al. demonstrated that while AIF was expressed intact in retinal cells cultured under dark conditions, it was expressed as two fragments under blue light conditions. Furthermore, RGCs exposed to blue light reportedly showed a lower survival rate than those exposed to dark illumination, and the survival rate increased significantly when the expression of RIP1 and RIP3 proteins was inhibited through small interfering RNA (siRNA) technology. It is evident that blue light activates both apoptosis and apoptotic necrosis in retinal cells, which may contribute to the onset or exacerbation of glaucoma. [4]

Pasquale et al., have shown that UV light could also contribute to the development of pseudo-exfoliative glaucoma (PXG). Their study showed that every hour per week spent outdoors during the summer, averaged over a lifetime, was associated with a 4% increased odds of exfoliation syndrome (pooled odds ratio = 1.04; 95% CI: 1.00-1.07; p = .03). For every 1% of average lifetime summer time between 10 a.m. and 4 p.m. that sunglasses were worn, the odds of exfoliation syndrome decreased by 2% (odds ratio = 0.98; 95% CI: 0.97-0.99; p < .001). [5]

After controlling for important environmental covariates, history of work over water or snow was associated with increased odds of exfoliation syndrome (odds ratio = 3.86; 95% CI: 1.36-10.9). There is considerable evidence that climatic factors contribute to the pseudo-exfoliative changes. For example, aboriginal Australians who spend substantial time outdoors have a higher prevalence of pseudo-exfoliative syndrome (PEX).

Dai et al., have shown that both genetic predispositions to using sun/UV protection and having an ease of skin tanning response are associated with a decreased risk of PXG in the European population. According to them, one possible explanation for this association is that UV radiation may influence the expression of nonpigmented ciliary epithelial cells (NPE) in humans through an aryl hydrocarbon receptor (AHR)-associated pathway, thereby contributing to the development of PXG. [6]

Clusterin, produced by NPE, serves as an effective extracellular chaperone, its deficiency in the anterior segment can promote stress-induced aggregation and the stable deposition of pathologic extracellular matrix products—hallmarks of PXG. Zenkel et al. have observed an oxidative milieu in the anterior chamber of PEX eyes, potentially leading to stress-induced protein modifications and misfolding. [7] However, whether oxidation of the UV radiation contributes to this process remains uncertain. TGF-β1, oxidation and UV radiation can induce a significant upregulation in LOXL1 gene expression in human tenon fibroblasts and PEX. UVB has been associated with the increased levels of TGF-beta 1 mRNA, and UVA exposure can induce oxidative damage. Nevertheless, it remains uncertain whether UV radiation affects LOXL1 through direct DNA damage, TGF-β1 mediation, or oxidative stress.

Oxidative stress has also been linked to POAG by increasing flow resistance of aqueous humor through the trabecular meshwork in the presence of high levels of hydrogen peroxide. [1]

TREATMENT OF GLAUCOMA WITH INFRA-RED LIGHT:

Red light increases cytochrome-c oxidase activity in the electron transport system, reducing inflammation and increasing antioxidant reactions to promote cell regeneration. PBM (Photobiomodulation) therapy, which is emerging as a new treatment for glaucoma, induces the inhibition of nitric oxide in the electron transport system and promotes an increase in the activity of cytochrome-C oxidase, reduces oxidative stress and inflammatory reactions in the eye, and increases energy production in the cells. A study by Dr. Galina has shown IOP reduction after 15 minutes of infrared-light exposure to healthy subjects. [7]

SEE POST ON IRL TREATMENT HERE: https://ourgsc.blogspot.com/search?q=Galina

Therefore, the minimization of UV and blue light exposure and the general application of red-light treatment strategies are anticipated to show synergistic effects with existing treatments for glaucoma and should be considered a necessary prospect for the future.

REFERENCES:

1. Ivanov IV, Mappes T, Schaupp P, Lappe C, Wahl S. Ultraviolet radiation oxidative stress affects eye health. J. Biophotonics. 2018; 11:e201700377
2. Osborne N.N., Lascaratos G., Bron A.J., Chidlow G., Wood J.P.M. A Hypothesis to Suggest That Light Is a Risk Factor in Glaucoma and the Mitochondrial Optic Neuropathies. Br. J. Ophthalmol. 2006;90:237–241.
3. Ahn SH, Suh JS, Lim GH, Kim TJ. The Potential Effects of Light Irradiance in Glaucoma and Photobiomodulation Therapy. Bioengineering (Basel). 2023 Feb 7;10(2):223.
4. Osborne N.N., Núñez-Álvarez C., del Olmo-Aguado S., Merrayo-Lloves J. Visual Light Effects on Mitochondria: The Potential Implications in Relation to Glaucoma. Mitochondrion. 2017;36:29–35.
5. Pasquale LR, Jiwani AZ, Zehavi-Dorin T, Majd A, Rhee DJ, Chen T, Turalba A, Shen L, Brauner S, Grosskreutz C, Gardiner M, Chen S, Borboli-Gerogiannis S, Greenstein SH, Chang K, Ritch R, Loomis S, Kang JH, Wiggs JL, Levkovitch-Verbin H. Solar exposure and residential geographic history in relation to exfoliation syndrome in the United States and Israel. JAMA Ophthalmol. 2014 Dec;132(12):1439-45. doi: 10.1001/jamaophthalmol.2014.3326. PMID: 25188364; PMCID: PMC4268013.
6. Jinyue Dai, Lingge Suo, Haocheng Xian, Zhe Pan, Chun Zhang; Investigating the Impact of Sun/UV Protection and Ease of Skin Tanning on the Risk of Pseudoexfoliation Glaucoma: A Mendelian Randomization Study. Invest. Ophthalmol. Vis. Sci. 2023;64(13):4. https://doi.org/10.1167/iovs.64.13.4.
7. Zenkel M, Kruse FE, Jünemann AG, Naumann GO, Schlötzer-Schrehardt U. Clusterin deficiency in eyes with pseudoexfoliation syndrome may be implicated in the aggregation and deposition of pseudoexfoliative material. Invest Ophthalmol Vis Sci. 2006 May;47(5):1982-90. doi: 10.1167/iovs.05-1580. PMID: 16639006.
8. Dimitrova, Galina & Gjorgjioska, Ana & Ilievska, Tatjana & Grkova-Mishkovska, Emilija & Ljubic, Antonela & Purelku, Merjem & Andonovski, Dragan & Stojcev, Sasho. (2019). The effect of infra-red light on intraocular pressure. Arquivos Brasileiros de Oftalmologia. 82. 10.5935/0004-2749.20190017