The potential retinal hazards of curing light use for dentists

Background: Many recent studies have focused on the potential hazards of blue light exposure to ocular health. One group with a unique blue light exposure risk is dentists, who use curing lights that emit intense blue light during restorative procedures. During these procedures, dentists often experience brief ocular exposure to these lights. The purpose of the present study was to explore whether such exposures may have an effect on the vision and ocular health of dentists. Methods: A group of 12 dentists who had experienced curing light exposure over a period of 10 or more years were compared to a group of eight control subjects with no such exposure. The subjects were tested for visual acuity and contrast sensitivity. Their retinas were examined using fundus imaging and optical coherence tomography. Macular pigment optical density was measured. The likelihood that brief blue light exposure could lead to ocular effects was further explored by subjecting a retinal pigment epithelial cell (RPE) line to such exposures. Results: Although no visual defects or ocular pathologies were found in either group, the dentist group differed from the control group in having increased macular thickness (P < 0.02), a higher incidence of macular vessel tortuosity (P < 0.05), and greater variance in their macular pigment optical density values (P < 0.01). RPE cells that received blue light exposure similar to those sustained by dentists demonstrated a change in physiology. Conclusions: Retinal changes were found in dentists, which, while not pathological in themselves, are associated with some retinal pathologies. Further studies are necessary to determine whether these signs correlate with the degree of curing light exposure and to determine whether they eventually develop into pathological conditions.

Fallopia Japonica and Prunella Vulgaris Inhibit Myopia Progression by Suppressing Akt and NFκB Mediated Inflammatory Reactions

The increased global incidence of myopia requires the establishment of therapeutic approaches. Previous studies have suggested that inflammation plays an important role in the development and progression of myopia. We used human retinal pigment epithelial cell to study the molecular mechanisms on how FJE and PVE lowering the inflammation of the eye. The effect of FJE and PVE in MFD induced hamster model and explore the role of inflammation cytokines in myopia. Expression levels of IL-6, IL-8, and TNF-&alpha; were upregulated in retinal pigment epithelium (RPE) cells treated with IL-6 and TNF-&alpha;. FJ extract (FJE) + PV extract (PVE) reduced IL-6, IL-8, and TNF-&alpha; expression in RPE cells. Furthermore, FJE and PVE inhibited inflammation by attenuating the phosphorylation of protein kinase B (AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-&kappa;B) pathway. In addition, we report two resveratrol + ursolic acid compounds from FJ and PV and their inhibitory activities against IL-6, IL-8, and TNF-&alpha; expression levels in RPE cells treated with IL-6 and TNF-&alpha;. FJE, PVE, and FJE + PVE were applied to MFD hamsters and their axial length was measured after 21 days. The axial length showed statistically significant differences between phosphate-buffered saline- and FJE-, PVE-, and FJE + PVE-treated MFD eyes. FJE + PVE suppressed expressions of IL-6, IL-8, and TNF-&alpha;. They also inhibited myopia-related transforming growth factor-beta (TGF)-&beta;1, matrix metalloproteinase (MMP)-2, and NF-&kappa;B expression while increasing type Ⅰ collagen expression. Overall, these results suggest that FJE + PVE may have a therapeutic effect on myopia and be used as a potential treatment option.

Diacerein Inhibits Myopia Progression through Lowering Inflammation in Retinal Pigment Epithelial Cell

Myopia is a highly prevalent refractive disorder. We investigated the effect of diacerein on monocular form deprivation (MFD) in hamsters as a possible therapeutic intervention. Diacerein is an anthraquinone derivative drug whose active metabolite is rhein. Diacerein or atropine was applied to the MFD hamsters, and their refractive error and axial length were measured after 21 days. The refractive error (control: − 0.91 ± 0.023 , atropine: − 0.3 ± 0.08 , and diacerein: − 0.27 ± 0.07 D ) and axial length (control: 0.401 ± 0.017 , atropine: 0.326 ± 0.017 , and diacerein: 0.334 ± 0.016 mm ) showed statistically significant differences between control, atropine-treated, and diacerein-treated MFD eyes. Furthermore, we determined the level of transforming growth factor-beta- (TGF-) β1, matrix metalloproteinase- (MMP-) 2, type I collagen, interleukin- (IL-) 6, IL-8, and monocyte chemoattractant protein- (MCP-) 1 in the retina. Atropine and diacerein suppressed levels of the myopia-related TGF-β1 and MMP-2 while increasing type I collagen expression. They also inhibited the interleukin IL-6, IL-8, and MCP-1 levels. Diacerein reduced the IL-6, IL-8, and MCP-1 expression in ARPE-19 cells. Furthermore, diacerein inhibited inflammation by attenuating the phosphorylation of protein kinase B (AKT) and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) pathway. This suggests that diacerein has a therapeutic effect on myopia and is a potential treatment option.

Autophagy dysregulation mediates the damage of high glucose to retinal pigment epithelium cells

AIM: To observe the role and mechanism of autophagy in retinal pigment epithelial cell (RPE) damaged by high glucose, so as to offer a new idea for the treatment of diabetic retinopathy (DR). METHODS: ARPE-19, a human RPE cell line cultured in vitro was divided into the normal control (NC), autophagy inhibitor 3-methyladenine (3-MA), high-glucose (HG), and HG+3-MA groups. Cell viability was detected by CCK-8 assay and the apoptosis rate was measured by flow cytometry. The protein expressions of apoptosis markers, including Bax, Bcl-2, and Caspase-3, as well as autophagy marker including microtubule-related protein 1 light chain 3 (LC3), p62, and mechanistic target of rapamycin (mTOR) were detected by Western blotting. Autophagic flux was detected by transfection with Ad-mCherry-GFP-LC3B. RESULTS: Under high glucose conditions, the viability of ARPE-19 was decreased, and the apoptosis rate increased, the protein expressions of Bax, Caspase-3, and LC3-II/LC3-I were all increased and the expressions of Bcl-2, p62 and p-mTOR decreased, and autophagic flux was increased compared with that of the controls. Treatment with 3-MA reversed all these changes caused by high glucose. CONCLUSION: The current study demonstrates the mechanisms of cell damage of ARPE-19 through high glucose/mTOR/autophagy/apoptosis pathway, and new strategies for DR may be developed based on autophagy regulation to manage cell death of RPE cells.

Pullulan Based Bioconjugates for Ocular Dexamethasone Delivery

Posterior segment eye diseases are mostly related to retinal pathologies that require pharmacological treatments by invasive intravitreal injections. Reduction of frequent intravitreal administrations may be accomplished with delivery systems that provide sustained drug release. Pullulan-dexamethasone conjugates were developed to achieve prolonged intravitreal drug release. Accordingly, dexamethasone was conjugated to ~67 kDa pullulan through hydrazone bond, which was previously found to be slowly cleavable in the vitreous. Dynamic light scattering and transmission electron microscopy showed that the pullulan-dexamethasone containing 1:20 drug/glucose unit molar ratio (10% w/w dexamethasone) self-assembled into nanoparticles of 461 ± 30 nm and 402 ± 66 nm, respectively. The particles were fairly stable over 6 weeks in physiological buffer at 4, 25 and 37 °C, while in homogenized vitreous at 37 °C, the colloidal assemblies underwent size increase over time. The drug was released slowly in the vitreous and rapidly at pH 5.0 mimicking lysosomal conditions: 50% of the drug was released in about 2 weeks in the vitreous, and in 2 days at pH 5.0. In vitro studies with retinal pigment epithelial cell line (ARPE-19) showed no toxicity of the conjugates in the cells. Flow cytometry and confocal microscopy showed cellular association of the nanoparticles and intracellular endosomal localization. Overall, pullulan conjugates showed interesting features that may enable their successful use in intravitreal drug delivery.