Corneal epithelium and UV‐protection of the eye

Ringvold, Amund

doi:10.1034/j.1600-0420.1998.760205.x

Cited by 88 publications

(61 citation statements)

References 17 publications

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“…The fluorescence calculated as arbitrary units per milligram of protein is higher in the corneal tissue than in SIRC. Indeed it is likely that the release of other fluorescent substances produced by the ROS-generating system on articulate arrangement of corneas can justify this increase [8,51,52].…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, the effect of UV light has been extensively investigated [1][2][3][4][5][6][7][8]. It has been reported that biotoxic epiphenomena may take place when the threshold level of radiation absorbed in corneal tissues is exceeded, and, consequently, permanent keratocyte damage or loss, epithelium destruction, endothelium edema and necrosis occur, as well as biochemical changes, such as ROS production, protein cross-linking, enzyme inactivation, DNA strand breaks and chemotactic factor release [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Ciuffi

Pisanello

Pagliai

et al. 2003

Journal of Photochemistry and Photobiology B: Biology

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Several corneal pathologies are characterized by the presence of reactive oxygen species (ROS); therefore, we evaluated the protection afforded by pirenoxine and melatonin to corneal cell culture and whole rabbit cornea from ultraviolet exposure and other oxidant systems.Rabbit cornea cell (SIRC) plates and whole corneas were exposed to UV-B (80 or 800 mJ/cm 2 ) or incubated with fMLPstimulated autologous macrophages, in the presence or absence of pirenoxine or melatonin (10 À5 M). The protective activity of compounds was assessed by measuring superoxide anion formation, inhibition of oxidation and mitochondrial viability. Moreover the ex vivo protective effect of pirenoxine and melatonin was verified in the whole cornea submitted to UV-B exposure in vitro.Our experimental data demonstrate that pirenoxine and melatonin were able to inhibit the superoxide formation and oxidative effect in cell culture and whole rabbit corneas submitted to UV-B exposure or to incubation with fMLP-stimulated autologous macrophages.Mitochondrial viability was restored in epithelial cells of rabbit cornea but not in SIRCs. Moreover, both compounds are also able to increase ex vivo epithelial corneal cell defences against the in vitro UV-B induced lipid peroxidation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Ciuffi

Pisanello

Pagliai

et al. 2003

Journal of Photochemistry and Photobiology B: Biology

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“…There is recent biophysical evidence showing that UV light penetrates and is differentially absorbed by ocular tissues. Their absorption pattern in the antero-posterior direction follows a wavelength-dependent decade (Ringvold and Davanger, 1985;Ringvold, 1997Ringvold, ,1998. The corneal epithelium absorbs UV wavelengths shorter than 310 nm (UV-B between 290 and 320 nm and UV-C between 200 and 290 nm) thereby acting as a filter and protecting the lens and retina from UV-induced damage (Fig.…”

Section: Uv Irradiation-induced Cellular Damagementioning

confidence: 99%

“…6). In doing so the corneal epithelium and lens protect the retina from UV irradiation-induced damage (Ringvold, 1998;Taylor et al, 1998;Podskochy et al, 2000). In addition, repeated subthreshold or single threshold UV-exposures lead to inhibition of mitosis, nuclear fragmentation and loss of the whole corneal epithelial layer.…”

Section: Uv Irradiation-induced Cellular Damagementioning

confidence: 99%

Stress-induced corneal epithelial apoptosis mediated by K+ channel activation

2006

Progress in Retinal and Eye Research

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One of the functional roles of the corneal epithelial layer is to protect the cornea, lens and other underlying ocular structures from damages caused by environmental insults. It is important for corneal epithelial cells to maintain this function by undergoing continuous renewal through a dynamic process of wound healing. Previous studies in corneal epithelial cells have provided substantial evidence showing that environmental insults, such as ultraviolet (UV) irradiation and other biohazards, can induce stress-related cellular responses resulting in apoptosis and thus interrupt the dynamic process of wound healing. We found that UV irradiation-induced apoptotic effects in corneal epithelial cells are started by the hyperactivation of K + channels in the cell membrane resulting in a fast loss of intracellular K + ions. Recent studies provide further evidence indicating that these complex responses in corneal epithelial cells are resulted from the activation of stressrelated signaling pathways mediated by K + channel activity. The effect of UV irradiation on corneal epithelial cell fate shares common signaling mechanisms involving the activation of intracellular responses that are often activated by the stimulation of various cytokines. One piece of evidence for making this distinction is that at early times UV irradiation activates a Kv3.4 channel in corneal epithelial cells to elicit activation of c-Jun N-terminal kinase cascades and p53 activation leading to cell cycle arrest and apoptosis. The hypothetic model is that UV-induced potassium channel hyperactivity as an early event initiates fast cell shrinkages due to the loss of intracellular potassium, resulting in the activation of scaffolding protein kinases and cytoskeleton reorganizations. This review article presents important control mechanisms that determine Kv channel activity-mediated cellular responses in corneal epithelial cells, involving activation of stress-induced signaling pathways, arrests of cell cycle progression and/or induction of apoptosis.

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“…These include antioxidants, lens chromophores, melanin, glutathione (GSH) peroxidase, superoxide dismutase, and heme oxygenase [106]. Radical scavengers such as vitamin E, vitamin C, [107,108] beta carotene, and ubiquinone [107] are other defense mechanisms.…”

Section: Ocular Photoprotectionmentioning

confidence: 99%

The Role of Ultraviolet Radiation in the Ocular System of Mammals

et al. 2014

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Abstract:With decreasing levels of ozone in the atmosphere, we are being exposed to higher levels of ultraviolet radiation (UVR) than ever before. UVR carries higher energy than visible light, and its effects on tissues include DNA damage, gene mutations, immunosuppression, oxidative stress and inflammatory responses. In the eye, UVR is strongly associated with the development of basal and squamous cell carcinoma of the eyelid, pterygium, photokeratitis, climatic droplet keratopathy, ocular surface squamous neoplasia, cataracts, and uveal melanoma, and is weakly associated with age-related macular degeneration. Despite overwhelming evidence regarding the deleterious effects on UVR, public health measures to encourage UV protection of the eyes is generally lacking. Options for photoprotection include sunglasses, wide brim hats, windshields, plastic films for side windows in cars, UV blocking contact lenses, and following the UV Index report daily. The American National Standards Institute currently has regulations regarding properties of UV blocking sunglasses; however, compliance in the US is not mandatory. On the other hand, UVR does have therapeutic applications in the eye, particularly, riboflavin activated by ultraviolet A light (UVA) radiation is used clinically to slow the progression of keratoconus, post-LASIK keratectasia, and bullous keratopathy by crosslinking corneal collagen fibers. OPEN ACCESSPhotonics 2014, 1 348 Additionally, riboflavin activated by UVA has been shown to have antibacterial, antiviral, and antiparasitic effects. This is clinically relevant in the treatment of infectious keratitis. Finally, exposure to low levels of light in the UV spectrum has been found to regulate the growth of the eye and lack of adequate exposure may increase the risk of development and progression of myopia.

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Corneal epithelium and UV‐protection of the eye

Abstract: ABSTRACT.Purpose: To study UV-absorption and UV-induced fluorescence in the bovine corneal epithelium. Methods: Spectrophotometry and spectrofluorimetry.

Cited by 88 publications

References 17 publications

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Stress-induced corneal epithelial apoptosis mediated by K+ channel activation

The Role of Ultraviolet Radiation in the Ocular System of Mammals

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