refractive

Mixing-induced reactions play a key role in a large range of biogeochemical and contaminant transport processes in the subsurface. Fluid flow through porous media was recently shown to exhibit chaotic mixing dynamics at the pore scale, enhancing microscale concentration gradients and controlling mixing rates. While this phenomenon is likely ubiquitous in environmental systems, it is not known how it affects chemical reactions. Here, we use refractive index matching and laser-induced fluorescence imaging of a bimolecular redox reaction to investigate the consequence of pore scale chaotic mixing on the reaction rates...

The UV/Vis absorption energies νmax of Reichardt's dye B30 with respect to ET (30) and 4-nitroaniline (NA) are investigated as a function of the solvent composition Nav,z. in co-solvent/water mixtures. Nav,z . is the average molar concentration of the solvent mixture at a given solvent fraction z. The z can be the mole, the volume or the mass fraction. The co-solvents considered were acetonitrile, acetone, tetrahydrofuran, pyridine, piperidine and 2-(diethylamino)-ethanol. Acetone and acetonitrile can be expected to slightly enhance the water structure at low co-solvent concentrations...

Quasi-one-dimensional (quasi-1D) van der Waals crystal fibrous red phosphorus (RP) exhibits pronounced in-plane optical anisotropy, positioning it as a potential candidate for polarization-related micro-nano devices. Unfortunately, a comprehensive investigation into the complex refractive index of fibrous RP and the structure-activity relationship connecting the distinctive quasi-1D structure with optical anisotropy is currently deficient. Herein, we have collectively determined the complex refractive index of the fibrous RP flakes within the ab-plane through Kramers-Kronig (KK) analysis and theoretical calculation...

BACKGROUND: The practice of immediate sequential bilateral cataract surgery (ISBCS) was more widely adopted in the UK during the COVID-19 pandemic, in response to limited surgical capacity and the risk of nosocomial infection. This study reports on a single site experience of ISBCS in Northern Ireland. METHODS: Data was collected prospectively between 17th November 2020 and 30th November 2021. The ISBCS surgical protocol, recommended by RCOphth and UKISCRS, was followed...

PURPOSE: To compare the outcomes of the Tecnis Eyhance ICB00 IOL, designed to enhance intermediate vision, to a conventional Tecnis Monofocal ZCB00 IOL. METHODS: This retrospective analysis compared two cohorts of patients undergoing lens replacement surgery with bilateral implantation of the Tecnis ICB00 or the Tecnis ZCB00 IOL (383 patients in each group). Monocular and binocular uncorrected distance (UDVA), intermediate (UIVA; 66cm), and near (UNVA; 40cm) visual acuities, refractive predictability, and patient-reported outcomes were compared...

INTRODUCTION: The recently developed single-shade composite resin (using the concept of structural coloring) is a promising option to eliminate the process and subjectivity of shade selection. However, current evidence of its performance is still insufficient. This study aimed to evaluate the color matching, color stability, and refractive index (RI) of single-shade restorations compared with conventional composite resin. METHODS: This in vitro study was conducted on 48 extracted maxillary premolars...

BACKGROUND: Schoolteachers who have knowledge on eye diseases can detect early children with eye disorders and refer them promptly to an eye specialist. The aim of this study is to assess the effectiveness of teachers in a vision screening program for primary school children in Abakaliki. METHODS: This descriptive cross-sectional study was conducted among 20 randomly selected primary schoolteachers in Abakaliki to screen for vision abnormalities and detect eye problems among 350 children from 5 schools...

BACKGROUND: Non-traumatic ectopia lentis is a rare ocular disorder usually associated with syndromes like Marfans's syndrome, Weil-Marchesani and Homocystinuria. Ectopia lentis can lead to profound visual loss from refractive errors, glaucoma as well as retinal detachment if left unattended. AIM: The aim of this study was to describe the clinical profile of patients with non-traumatic ectopia lentis in a paediatric ophthalmology clinic in Ibadan, Nigeria. METHODS: The clinical records of children ≤16 years diagnosed with non- traumatic ectopia lentis at the Paediatric Ophthalmology Clinic, University College Hospital Ibadan, from May 1, 2015 to Dec 31, 2019 were retrospectively reviewed...

Objective: To explore the differences in clinical characteristics and interocular interactions between patients with anisometropic amblyopia and ametropic amblyopia. Methods: Cross-sectional study. The newly diagnosed anisometropic (the binocular difference in spherical equivalent≥1.00 D) amblyopia patients and ametropic amblyopia patients (aged 4 to 6 years) in Beijing Tongren Hospital from January 2020 to December 2022 were involved. Patients were further categorized by the refractive status after cycloplegia, including hyperopia, myopia, astigmatism, hyperopia with astigmatism, myopia with astigmatism, mild anisometropia and severe anisometropia...

PURPOSE: To assess whether the use of measured posterior corneal astigmatism (PCA) values improves the prediction accuracy of toric intraocular lens power formulas, compared to predicted PCA values, when the orientation of the steep axis of PCA is non-vertical. DESIGN: Retrospective observational cohort study METHODS: 418 eyes of 344 patients were included in the study. Prediction errors (PE) for postoperative refractive astigmatism at 4 weeks postoperatively were determined using vector analysis and compared for the following toric intraocular lens power formulas: Barrett Toric with predicted posterior corneal astigmatism (PPCA); Barrett Toric with measured posterior corneal astigmatism (MPCA); EVO Toric PPCA; EVO Toric MPCA; Holladay I with Abulafia-Koch regression...

Studies in animal models and humans have shown that refractive state is optimized during postnatal development by a closed-loop negative feedback system that uses retinal image defocus as an error signal, a mechanism called emmetropization. The sensor to detect defocus and its sign resides in the retina itself. The retina and/or the retinal pigment epithelium (RPE) presumably releases biochemical messengers to change choroidal thickness and modulate the growth rates of the underlying sclera. A central question arises: if emmetropization operates as a closed-loop system, why does it not stop myopia development? Recent experiments in young human subjects have shown that (1) the emmetropic retina can perfectly distinguish between real positive defocus and simulated defocus, and trigger transient axial eye shortening or elongation, respectively...

Tissue clearing is an essential prerequisite for 3D volumetric imaging of larger tissues or organs. Here, we present a detailed protocol for optical, aqueous-based clearing of adult murine tissues using EZ Clear. We describe steps to ensure successful perfusion and fixation of organs from the adult mouse and supply guidelines for optimal lipid removal, refractive index matching, and tissue clearing. Finally, we provide imaging parameters for visualizing both exogenous perfused fluorescent dyes and endogenous fluorescence reporters in the adult mouse...

PURPOSE OF REVIEW: Pediatric refractive surgery has been growing at a steady pace since its introduction in the early 1980 s. This article will review common laser refractive surgeries performed on pediatric patients along with controversies regarding the practice. RECENT FINDINGS: Pediatric refractive surgery is reserved for a small population of children who fail amblyopic treatment due to high anisometropic refractive errors. Publications over the years have treated these children with various types of laser refractive surgery...

A validated rapid high-performance liquid chromatography (HPLC)-refractive index (RI) method was developed for the identification and quantification of glucose and xylose in hydrolyzed bagasse extract. The separation of compounds was achieved on Eurokat® H column (300 × 8 mm, 10 μm) at 75°C, using 0.01 N sulfuric acid solution as mobile phase and 0.6 mL/min as flow rate. The method was validated based on accuracy, precision, linearity, robustness, uncertainty, limit of detection (LOD) and limit of quantification (LOQ)...

PURPOSE: To evaluate the predictive accuracy of modern intraocular lens (IOL) formulas and axial length (AL) adjusted traditional IOL formulas, including Wang-Koch and Cooke-modified AL (CMAL) method, in long eyes with plate-haptic IOLs, and to compare refractive prediction error variances with C-loop IOLs. DESIGN: Retrospective consecutive case series study. METHODS: Data from 391 eyes with Zeiss 509M and 302 eyes with Alcon SN6CWS implants in highly myopic patients, following cataract surgery from January 2019 to November 2023, were collected...

PURPOSE: To evaluate the visual outcomes and perioperative complications for cataract surgery in eyes with axial length (AL) > 33.0 mm. DESIGN: Prospective clinical cohort study. METHODS: One hundred and twenty-two eyes with moderate high myopia (26.0 mm ≤ AL<28.0 mm, control group), and 118 eyes with extreme high myopia (AL > 33.0 mm, EHM group) were followed up after cataract surgery (one week and one year post-op). Myopic maculopathy grading according to ATN system, best-corrected visual acuity (BCVA), and complications were compared...

PURPOSE OF REVIEW: Higher degrees of myopia are currently being treated with refractive surgery. However, there is limited characterization and outcomes data for this cohort. This article aims to review the literature on highly myopic patients who had refractive surgery and present a retrospective analysis of 149 patients (270 eyes) with high to extreme myopia (≤-5.0D SE) who underwent refractive surgery [laser-assisted subepithelial keratomileusis (LASIK), photorefractive keratectomy (PRK), or implantable collamer lense (ICL)] at a single practice...

PURPOSE OF REVIEW: Laser keratorefractive surgery achieves excellent visual outcomes for refractive error correction. With femtosecond laser, small incision lenticule extraction (SMILE) is an increasingly viable alternative to laser-assisted in situ keratomileusis (LASIK). Comparative studies demonstrate similar efficacy and predictability between SMILE and LASIK, making it difficult for clinicians to choose which to use. This review thus compares femtosecond-LASIK (FS-LASK) and SMILE in various scenarios, to assist clinicians in deciding which refractive surgery procedure to recommend...

PURPOSE OF REVIEW: To review corneal crosslinking for keratoconus and corneal ectasia, and recent developments in the field. This study will review the mechanism of crosslinking, clinical approaches, current results, and potential future innovations. RECENT FINDINGS: Corneal crosslinking for keratoconus was first approved by U.S. FDA in 2016. Recent studies have confirmed the general long-term efficacy of the procedure in decreasing progression of keratoconus and corneal ectasia...

The photoinduced dipole force (PiDF) is an attractive force arising from the Coulombic interaction between the light-induced dipoles on the illuminated tip and the sample. It shows extreme sample-tip distance and refractive index dependence, which is promising for nanoscale infrared (IR) imaging of ultrathin samples. However, the existence of PiDF in the mid-IR region has not been experimentally demonstrated due to the coexistence of photoinduced thermal force (PiTF), typically one to two orders of magnitude higher than PiDF...