Ultraviolet protection in eye and face protection against biological hazards.

Background: In the development of eye and face protection standards against biological hazards, it is important to consider that the eye and face protectors may be used in the outdoor environment, where ultraviolet (UV) exposure from the sun is much higher than indoors. Workers affected include paramedics, ambulance officers and clinical testing personnel.

Methods: Spectral transmittances (280-780 nm) were measured on eight face shields and one goggle of the types used in hospital and clinical environments, three overhead projector sheets and an occupational impact protective goggle.

Advancing full-field metrology: rapid 3D imaging with geometric phase ferroelectric liquid crystal technology in full-field optical coherence microscopy.

Optical coherence microscopy (OCM) is a variant of OCT in which a high-numerical aperture lens is used. Full-field OCM (FF-OCM) is an emerging non-invasive, label-free, interferometric technique for imaging of surface structures or semi-transparent biomedical subjects with micron-scale resolutions. Different approaches to three dimensional full-field optical metrology are reviewed.

In-vivo corneal confocal microscopy: Imaging analysis, biological insights and future directions.

In-vivo corneal confocal microscopy is a powerful imaging technique which provides clinicians and researcher with the capabilities to observe microstructures at the ocular surfaces in significant detail. In this Mini Review, the optics and image analysis methods with the use of corneal confocal microscopy are discussed. While novel insights of neuroanatomy and biology of the eyes, particularly the ocular surface, have been provided by corneal confocal microscopy, some debatable elements observed using this technique remain and these are explored in this Mini Review.

Feasibility of Silicon Quantum Dots as a Biomarker for the Bioimaging of Tear Film.

This study investigated the fluorescence and biocompatibility of hydrophilic silicon quantum dots (SiQDs) that are doped with scandium (Sc-SiQDs), copper (Cu-SiQDs), and zinc (Zn-SiQDs), indicating their feasibility for the bioimaging of tear film. SiQDs were investigated for fluorescence emission by the in vitro imaging of artificial tears (TheraTears), using an optical imaging system. A trypan blue exclusion test and MTT assay were used to evaluate the cytotoxicity of SiQDs to cultured human corneal epithelial cells.

Glaucoma diagnosis using multi-feature analysis and a deep learning technique.

In this study, we aimed to facilitate the current diagnostic assessment of glaucoma by analyzing multiple features and introducing a new cross-sectional optic nerve head (ONH) feature from optical coherence tomography (OCT) images. The data (n = 100 for both glaucoma and control) were collected based on structural, functional, demographic and risk factors. The features were statistically analyzed, and the most significant four features were used to train machine learning (ML) algorithms.

Genome-wide identification and prediction of SARS-CoV-2 mutations show an abundance of variants: Integrated study of bioinformatics and deep neural learning.

Genomic data analysis is a fundamental system for monitoring pathogen evolution and the outbreak of infectious diseases. Based on bioinformatics and deep learning, this study was designed to identify the genomic variability of SARS-CoV-2 worldwide and predict the impending mutation rate. Analysis of 259044 SARS-CoV-2 isolates identified 3334545 mutations with an average of 14.

The effect of blue light filtering lenses on speed perception.

Blue-light filtering lenses (BFLs) are marketed to protect the eyes from blue light that may be hazardous to the visual system. Because BFLs attenuate light, they reduce object contrast, which may impact visual behaviours such as the perception of object speed which reduces with contrast. In the present study, we investigated whether speed perception is affected by BFLs.

Modelling the effect of light through commercially available blue-blocking lenses on the human circadian system.

Clinical Relevance: Wearing blue-blocking lenses (BBLs) in the evening hours may not be effective in improving sleep quality. Optometrists need to be informed in prescribing BBLs by highlighting the consequences of their wear to the circadian system.

Background: Excessive exposure to artificial light, particularly at short wavelengths, during the evening, may disrupt normal nocturnal melatonin production, which is a natural process of the circadian rhythm and affect sleep quality.

The Effect of Blue-blocking Lenses on Photostress Recovery Times.

Significance: The selective reduction in visible wavelengths transmitted through commercially available blue-blocking lenses (BBLs) is known to influence the appearance and contrast detection of objects, particularly at low light levels. This influence may impair the human retinal receptor response time to dynamic light changes during photostress events.

Purpose: This study aimed to assess whether BBLs selectively affect photostress recovery times (PSRTs) for chromatic and achromatic stimuli of different Weber contrasts that were viewed on a dark black background.

Effect of blue-blocking lenses on colour discrimination.

Clinical Relevance: Tinted lenses may adversely affect colour discrimination. Before recommending tinted lenses to patients, practitioners should bear in mind any effects on colour discrimination. The effects of 'blue-blocking' spectacle lenses with high luminous transmittance on colour vision is not a concern.

Effect of blue-blocking lenses on colour contrast sensitivity.

Clinical Relevance: There is a significant unintended consequences of blue-blocking lenses on visual behaviour, particularly for the detection of colour. Optometrists need to be mindful of this when prescribing the appropriate blue-blocking lenses for individuals who work in environments in which blue light is prevalent.

Background: The selective reduction in visible wavelengths transmitted through commercially available blue-blocking lenses is known to influence object appearance and luminance contrast, and also potentially object colour contrast.

Hard x-ray phase-contrast microscopy using a Gabor hologram without a zero-order term.

In order to achieve a nanometer-scale resolution in an x-ray microscopy system, a Gabor-type hologram was produced by eliminating the zero-order term of the object diffraction pattern. In this system, a Fresnel zone plate was used for strong illumination of an object, and the zero-order diffraction was physically eliminated by a center stop. An accurate phase plate of /2 in the Zernike method was numerically created, and the phase-contrast image was realized.

Quantum Dots in Ophthalmology: A Literature Review.

: The aim of the current review was to summarize the current applications, the latest advances and importantly, highlight research gaps in the use of quantum dots in the eye. Quantum dots are nanoscale semiconductor crystals with characteristic size and tunable optical properties, which deliver bright and stable fluorescence suitable for bioimaging and labelling. : A systematic search was conducted following the PRISMA guidelines.

Modelling the effect of commercially available blue-blocking lenses on visual and non-visual functions.

Background: Blue-blocking lenses (BBLs) are marketed as providing retinal protection from acute and cumulative exposure to blue light over time. The selective reduction in visible wavelengths transmitted through BBLs is known to influence the photosensitivity of retinal photoreceptors, which affects both visual and non-visual functions. This study measured the spectral transmittance of BBLs and evaluated their effect on blue perception, scotopic vision, circadian rhythm, and protection from photochemical retinal damage.

Role of random biopsies in surveillance of dysplasia in ulcerative colitis patients with high risk of colorectal cancer.

Background/aims: Recent data suggest that the incidence of ulcerative colitis (UC) related colorectal cancer (CRC) in India is similar to that of West. The optimum method for surveillance is still a debate. Surveillance with random biopsies has been the standard of care, but is a tedious process.

Complex mucinous cystadenoma of undetermined malignant potential of the urachus: a rare case with review of the literature.

Urachal carcinoma is an uncommon neoplasm. Benign urachal tumours are extremely rare. All urachal mucinous tumours, regardless of tumour type, have the potential to behave in an aggressive clinical manner that includes the development of pseudomyxoma peritonei.

Assessing the aggregation behaviour of iron oxide nanoparticles under relevant environmental conditions using a multi-method approach.

Iron nanoparticles are becoming increasingly popular for the treatment of contaminated soil and groundwater; however, their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Assessing their stability under environmental conditions is crucial for determining their environmental fate. A multi-method approach (including different size-measurement techniques and the DLVO theory) was used to thoroughly characterise the behaviour of iron oxide nanoparticles (Fe2O3NPs) under environmentally relevant conditions.

Characterisation of Fe-oxide nanoparticles coated with humic acid and Suwannee River natural organic matter.

Iron oxide nanoparticles are becoming increasingly popular for various applications including the treatment of contaminated soil and groundwater; however, their mobility and reactivity in the subsurface environment are significantly affected by their tendency to aggregate. One solution to overcome this issue is to coat the nanoparticles with dissolved organic matter (DOM). The advantages of DOM over conventional surface modifiers are that DOM is naturally abundant in the environment, inexpensive, non-toxic and readily adsorbed onto the surface of metal oxide nanoparticles.

White-light interference microscopy: minimization of spurious diffraction effects by geometric phase-shifting.

A common problem when profiling surfaces with steps or discontinuities using white-light (coherence-probe) interferometry is localized spikes (batwings) or spurious peaks due to diffraction effects. We show that errors due to these effects can be minimized by processing the irradiance data obtained with an achromatic phase-shifter operating on the geometric (Pancharatnam) phase to yield the values of the surface height.

White-light interference microscopy: a way to obtain high lateral resolution over an extended range of heights.

A problem with conventional techniques of interference microscopy, when profiling surfaces with an extended range of heights, is that only points on a single plane are in sharp focus. Other points, which are higher or lower, may be out of focus, with a consequent loss of lateral resolution. We show that white-light interference microscopy, with an achromatic phase-shifter, makes it possible to produce a three-dimensional representation of such surfaces with high lateral resolution over the entire range of heights.

Low-coherence interference microscopy with an improved switchable achromatic phase-shifter.

We present results obtained with a computer-controlled low-coherence interference microscope featuring a modified optical layout that uses a pair of fast switchable achromatic phase-shifters. This layout makes it possible to use ferro-electric liquid-crystal devices made with readily available FLC materials having a switching angle of 45 degrees , and obtain phase shifts of 0 degrees and +/-90 degrees . The use of phase shifts of 0 degrees and +/-90 degrees simplifies calculations of the fringe visibility and the fractional fringe-order and yields maximum accuracy.

White-light interference microscopy: effects of multiple reflections within a surface film.

The effects of the presence of a transparent thin film on a test surface in white-light interferometric surface profiling are investigated. An expression is obtained for the output intensity variations in a Michelson interferometer which includes the effect of multiple reflections within the thin film. The number of reflections that need to be considered to obtain good convergence to the correct solution is discussed.

Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator.

We describe a computer-controlled low-coherence interference microscope, based on a Linnik interferometer configuration that can rapidly and accurately map the shape of micro-machined surfaces exhibiting steps and discontinuities. The novel feature of the system is a fast, switchable achromatic phase-modulator operating on the geometric phase, using a pair of ferro-electric liquid crystal devices.