SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Cornea

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Small incision lenticule extraction or SMILE is a novel form of ‘flapless’ corneal refractive surgery that was adapted from refractive lenticule extraction (ReLEx). SMILE uses only one femtosecond laser to complete the refractive surgery, potentially reducing surgical time, side effects, and cost. If successful, SMILE could potentially replace the current, widely practiced laser in-situ keratomileusis or LASIK. The aim of this study is to evaluate whether SMILE is non-inferior to LASIK in terms of refractive outcomes at 3 months post-operatively.

Concepts: Surgery, Laser, Cornea, Ophthalmology, The Current, Refractive surgery, LASIK, Laser surgery

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The aim of this study was to investigate the feasibility of inducing rat neural crest cells (NCC) to differentiate to functional corneal endothelial cell (CEC)-like cells in vitro. Rat NCC were induced with adult CEC-derived conditioned medium. Immunofluorescence, flow cytometry and real time RT-PCR assay were used to detect expression of the corneal endothelium differentiation marker N-cadherin and transcription factors FoxC1 and Pitx2. CFDA SE-labeled CEC-like cells were transplanted to the corneal endothelium of a rat corneal endothelium deficiency model, and an eye-down position was maintained for 24 hours to allow cell attachment. The animals were observed for as long as 2 months after surgery and underwent clinical and histological examination. Spindle-like NCC turned to polygonal CEC-like after induction and expressed N-cadherin, FoxC1, Pitx2, zonula occludens-1 and sodium-potassium pump Na(+)/K(+) ATPase. The corneas of the experimental group were much clearer than those of the control group and the mean corneal thickness in the experimental group was significantly less than in the control group7, 14, 21 and 28 days after surgery. Confocal microscopy through focusing and histological analysis confirmed that green fluorescence-positive CEC-like cells formed a monolayer covering the Descemet’s membrane in the experimental group. In conclusion, CEC-like cells derived from NCCs displayed characters of native CEC, and the induction protocol provides guidance for future human CEC induction from NCC.

Concepts: DNA, Gene expression, Embryo, Developmental biology, Epithelium, Endothelium, Cornea, Corneal endothelium

170

PURPOSE: To investigate the normative data of ocular axial length and its associations in Chinese. METHOD: The population-based Beijing Eye Study 2011 is a cross-sectional study performed in Greater Beijing. The study included 3468 individuals (1963 (56.6%) women) with a mean age of 64.6±9.8 years (range: 50-93 years). A detailed ophthalmic and medical examination was performed. Axial length was measured by optical low-coherence reflectometry. RESULTS: Axial length measurements were available for 3159 (91.1%) study participants. Mean axial length was 23.25±1.14 mm (range: 18.96-30.88 mm). In multivariate analysis, axial length was significantly associated with the systemic parameters of higher age (P<0.001), higher body height (P = 0.003), higher level of education (P<0.001) and urban region of habitation (P<0.001), and with the ocular parameters of thicker central cornea (P = 0.001), higher corneal curvature radius (P<0.001), deeper anterior chamber (P<0.001), thicker lens (P<0.001), more myopic refractive error (P<0.001), larger pupil diameter (P = 0.018), and higher best corrected visual acuity (P<0.001). It was additionally and negatively associated with the lens vault (P<0.001). In highly myopic eyes, axial length was significantly associated with lower level of education (P = 0.008), more myopic refractive error (P<0.001), and lower best corrected visual acuity (P = 0.034). CONCLUSIONS: Mean ocular axial length in the older adult population of Greater Beijing (23.25±1.14 mm) was similar to the value measured in other urban populations and was higher than in a rural Central Indian population. The association between axial length and older age may potentially be associated with a survival artifact. The association between axial length and body height agrees with the general association between anthropomorphic measures and eye globe size. The association with the level of education and urban region of habitation confirms with previous studies. In contrast in highly myopic eyes, axial length was negatively associated with educational level and best corrected visual acuity.

Concepts: Eye, Visual acuity, Cornea, Myopia, Contact lens, Refractive error, Length, Pupil

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To compare the performance of two novel multipurpose disinfecting solutions (MPDS) in preventing silicone hydrogel contact lens dehydration, provide higher scores of subjective comfort and stable optical quality during a month of lens wear in neophyte volunteers.

Concepts: Cornea, Myopia, Lens, Contact lens, Contact lenses, Corrective lens, Intraocular lens, Oxygen permeability

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Second Harmonic Generation (SHG) microscopy recently appeared as an efficient optical imaging technique to probe unstained collagen-rich tissues like cornea. Moreover, corneal remodeling occurs in many diseases and precise characterization requires overcoming the limitations of conventional techniques. In this work, we focus on diabetes, which affects hundreds of million people worldwide and most often leads to diabetic retinopathy, with no early diagnostic tool. This study then aims to establish the potential of SHG microscopy for in situ detection and characterization of hyperglycemia-induced abnormalities in the Descemet’s membrane, in the posterior cornea.

Concepts: Optics, Diabetes mellitus, Laser, Diabetes, Cornea, Diabetic retinopathy, Nonlinear optics, Descemet's membrane

169

Combination of riboflavin/UVA cross-linking (CXL) and excimer laser ablation is a promising therapy for treating corneal ectasia. The cornea is strengthened by cross-linking, while the irregular astigmatism is reduced by laser ablation. This study aims to compare the efficacy of excimer laser ablation on porcine corneas with and without cross-linking.

Concepts: Laser, Cornea, Corneal transplantation, Refractive surgery, Contact lens, LASIK, Excimer laser, Keratoconus

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Current treatments for reversible blindness caused by corneal endothelial cell failure involve replacing the failed endothelium with donor tissue using a one donor-one recipient strategy. Due to the increasing pressure of a worldwide donor cornea shortage there has been considerable interest in developing alternative strategies to treat endothelial disorders using expanded cell replacement therapy. Protocols have been developed which allow successful expansion of endothelial cells in vitro but this approach requires a supporting material that would allow easy transfer of cells to the recipient. We describe the first use of plastic compressed collagen as a highly effective, novel carrier for human corneal endothelial cells. A human corneal endothelial cell line and primary human corneal endothelial cells retained their characteristic cobblestone morphology and expression of tight junction protein ZO-1 and pump protein Na+/K+ ATPase α1 after culture on collagen constructs for up to 14 days. Additionally, ultrastructural analysis suggested a well-integrated endothelial layer with tightly opposed cells and apical microvilli. Plastic compressed collagen is a superior biomaterial in terms of its speed and ease of production and its ability to be manipulated in a clinically relevant manner without breakage. This method provides expanded endothelial cells with a substrate that could be suitable for transplantation allowing one donor cornea to potentially treat multiple patients.

Concepts: Protein, Cell, Collagen, Epithelium, Endothelium, Cornea, Corneal endothelium

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Numerous studies have been completed on glaucoma pathogenesis. However, the potential and controversial interaction between ocular biomechanical properties and the glaucomatous diseases process has received much more attention recently. Previous studies have found that collagen tissues gain mutation change in glaucoma patients. This study was conducted to determine the role of collagen in the biomechanics of glaucoma in humans. Its changes may be the result of mechanical modifications brought on by intraocular pressure (IOP) fluctuations. More importantly, biomechanics and genetic evidence indicate that the mutation of collagen may play a role in the process of glaucoma. Alteration of collagen in the outflow pathway may alter mechanical tissue characteristics and a concomitant increase of aqueous humor outflow resistance and elevation of IOP. The variations of collagen, leading to inter-individual differences in scleral and lamina cribrosa properties, result in different susceptibility of individuals to elevated IOP. Therefore, this study hypothesized that collagen mutations may be an original cause of glaucoma.

Concepts: Bone, Genetics, Mutation, Cartilage, Cornea, Intraocular pressure, Biomechanics, Aqueous humour

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Keratitis (inflammation of the cornea) can result from contact lens wear or other causes. Keratitis from all causes, including contact lens wear, results in approximately 1 million clinic and emergency department visits annually, with an estimated cost of $175 million in direct health care expenditures in 2010 (1). Approximately 41 million U.S. residents wear contact lenses, and in 2014, >99% of contact lens wearers surveyed reported at least one behavior that puts them at risk for a contact lens-related eye infection (2). The Center for Devices and Radiological Health at the Food and Drug Administration (FDA) regulates contact lenses as medical devices, and certain adverse events related to contact lenses are reported to FDA’s Medical Device Report (MDR) database. To describe contact lens-related corneal infections reported to the FDA, 1,075 contact lens-related MDRs containing the terms “ulcer” or “keratitis” reported to FDA during 2005-2015 were analyzed. Among these 1,075 reports, 925 (86.0%) were reported by a contact lens manufacturer and 150 (14.0%) by an eye care provider or patient. Overall, 213 (19.8%) reports described a patient who had a central corneal scar, had a decrease in visual acuity, or required a corneal transplant following the event. Among the reports, 270 (25.1%) described modifiable factors known to be associated with an increased risk for contact lens-related corneal infections, including sleeping in contact lenses or poor contact lens hygiene; the remainder did not provide details that permitted determination of associated factors. Continued efforts to educate contact lens wearers about prevention of contact lens-related eye infections are needed.

Concepts: Eye, Visual acuity, Cornea, Ophthalmology, Contact lens, Contact lenses, Keratitis, Optometry