Combined finite-element and scalar diffraction simulation of light scattering on zone edges of diffractive intraocular lenses.

A method has been developed to simulate the effects of scattered light on the image quality of optical systems. The coherent model is based on geometrical optics to take account of wavefront aberrations caused by lenses, applies finite-element calculation to solve Maxwell's equations around small scattering structures such as edges of diffractive surface zones, and uses scalar diffraction for free-space light propagation. The implementation is discussed in detail, and the operation is demonstrated on diffractive intraocular lenses. Point spread and modulation transfer functions are evaluated for an axial object point, taking account of scattered light as a function of slant angle and round radius of diffractive zone edges. Results show that, at a distance of ±200 Airy radius (i.e., ±2.1∘) from the axis, scattered irradiance is about 5 times more than without considering edge effects. Optimum round radius was found to be 7% of the step height, which agrees with simple geometrical optical estimations.

In-line particle size measurement during granule fluidization using convolutional neural network-aided process imaging.

This paper presents a machine learning-based image analysis method to monitor the particle size distribution of fluidized granules. The key components of the direct imaging system are a rigid fiber-optic endoscope, a light source and a high-speed camera, which allow for real-time monitoring of the granules. The system was implemented into a custom-made 3D-printed device that could reproduce the particle movement characteristic in a fluidized-bed granulator. The suitability of the method was evaluated by determining the particle size distribution (PSD) of various granule mixtures within the 100-2000 µm size range. The convolutional neural network-based software was able to successfully detect the granules that were in focus despite the dense flow of the particles. The volumetric PSDs were compared with off-line reference measurements obtained by dynamic image analysis and laser diffraction. Similar trends were observed across the PSDs acquired with all three methods. The results of this study demonstrate the feasibility of performing real-time particle size analysis using machine vision as an in-line process analytical technology (PAT) tool.

Assessment of Visual Quality Improvement as a Result of Spectacle Personalization.

Personalized spectacles customized according to an individual's facial anatomy were developed to provide enhanced visual performance and overall comfort when compared to standard spectacles. In this comparative crossover trial, each subject was randomly assigned to wear either personalized spectacles or standard spectacles for two weeks and then tried the second pair for another two weeks. Visual acuity and reading speed were measured, and visual quality and comfort were assessed using specific questionnaires. The correlation of the wearing parameters with the subjects' satisfaction was calculated. According to our results, the subjects wearing personalized glasses reported significantly less experience of swaying and significantly higher overall satisfaction compared to those wearing the control spectacles. At the end of the study, 62% of subjects preferred the personalized spectacles, and visual quality was the primary reason for their spectacle preference followed by wearing comfort. The difference from the ideal cornea-vertex distance was significantly lower when wearing the personalized spectacles compared to the control frames. In addition, the absolute value of the difference from the ideal cornea-vertex distance was significantly correlated with patient satisfaction. These results suggest that personalized spectacles, customized according to an individual's facial anatomy for the ideal wearing parameters, result in both visual and comfort advantages for wearers.

Development of Alkali Activated Inorganic Foams Based on Construction and Demolition Wastes for Thermal Insulation Applications.

Nowadays, the construction industry is challenged not only by increasingly strict environmental regulations, but also by a shortage of raw materials and additives. It is critical to find new sources with which the circular economy and zero waste approach can be achieved. Promising candidates are alkali activated cements (AAC), which offer the potential to convert industrial wastes into higher added value products. The aim of the present research is to develop waste-based AAC foams with thermal insulation properties. During the experiments, pozzolanic materials (blast furnace slag, fly ash, and metakaolin) and waste concrete powder were used to produce first dense and then foamed structural materials. The effects of the concrete fractions, the relative proportions of each fraction, the liquid/solid ratio, and the amount of foaming agents on the physical properties were investigated. A correlation between macroscopic properties (strength, porosity, and thermal conductivity) and micro/macro structure was examined. It was found that concrete waste itself is suitable for the production of AACs, but when combined with other aluminosilicate source, the strength can be increased from 10 MPa up to 47 MPa. The thermal conductivity (0.049 W/mK) of the produced non-flammable foams is comparable to commercially available insulating materials.

Enhancement of Hydrophilicity of Nano-Pitted TiO2 Surface Using Phosphoric Acid Etching.

Our research group developed a novel nano-pitted (NP) TiO2 surface on grade 2 titanium that showed good mechanical, osteogenic, and antibacterial properties; however, it showed weak hydrophilicity. Our objective was to develop a surface treatment method to enhance the hydrophilicity of the NP TiO2 surface without the destruction of the nano-topography. The effects of dilute and concentrated orthophosphoric (H3PO4) and nitric acids were investigated on wettability using contact angle measurement. Optical profilometry and atomic force microscopy were used for surface roughness measurement. The chemical composition of the TiO2 surface and the oxidation state of Ti was investigated using X-ray photoelectron spectroscopy. The ccH3PO4 treatment significantly increased the wettability of the NP TiO2 surfaces (30°) compared to the untreated control (88°). The quantity of the absorbed phosphorus significantly increased following ccH3PO4 treatment compared to the control and caused the oxidation state of titanium to decrease (Ti4+ → Ti3+). Owing to its simplicity and robustness the presented surface treatment method may be utilized in the industrial-scale manufacturing of titanium implants.

Optical analysis of Müller glia cells as light transporters through the retina.

One and half decades ago, Müller glia cells of the retina became subjects of extended research as optical waveguides. It was demonstrated that outside the fovea, these cells are capable of providing light transmission through the thicker parts of the retina from the vitreous surface to the photoreceptor cells. We combined optical modeling of the eye's optical system with numerical methods that describe light guiding within Müller cells to analyze efficiency of light capture and guidance at different peripheral positions. We show that higher order guided modes play an important role, especially in the case of higher incidence angles and extended geometry of the electromagnetic field distributions predicted by the eye's optical model. We analyze the mode structure excited at different retinal peripheral positions and show that actual construction of these cells optimizes light guiding. Our results refine previously published modeling results regarding Müller cells as waveguides and provide extension to the whole area of the retina.

The Impact of Deterministic Signal Loss on OCT Angiography Measurements.

Purpose: In this study, we aimed at investigating the impact of deterministic signal loss on image quality and, thus, on optical coherence tomography angiography (OCTA) measurements performed by the RTVue-XR Avanti System. Methods: Absorptive filters with different optical densities (ODs) were used to simulate signal loss in a controlled way in 30 eyes from 15 healthy subjects. Scan Quality (SQ), provided by the AngioVue software, was applied as a measure of image quality. Results: Assessing the effect of decreased light transmittance on SQ values as well as that of attenuated image quality on OCTA parameters revealed a strong systematic dependence between these quantities. Attenuated image quality was associated with significantly decreased macular and peripapillary vessel density (VD) values, and we calculated a correction factor of 2.27% to 3.97% for a one-unit change in SQ for the different VD parameters. Conclusions: Our findings suggest that the influence of systematic changes in image quality on OCTA parameters needs to be considered during patient follow-up in order to make valid assessment of progression. Translational Relevance: For accurate evaluation of longitudinal changes in OCTA parameters, equal scan quality or using a correction factor is suggested.

Objective quantification and spatial mapping of cataract with a Shack-Hartmann wavefront sensor.

Based on wavefront sensor images an objective and quantitative method is presented for characterising cataract. By separating direct and scattered light in the focal plane of the microlenses, the new procedure is able to make two-dimensional maps of the spatial variation of scattering properties in the crystalline lens, and also provides a single figure descriptive for the whole eye. The developed evaluation algorithm successfully quantifies cataract, especially that of nuclear type. To demonstrate its operation, a custom-built measurement setup was constructed using a Shack-Hartmann wavefront sensor with [Formula: see text] microlenses to capture 12-bit images of the pupil plane, and a superluminescent diode of 830 nm wavelength as a light source. Slit-lamp clinical measurements served as reference for calibration and to estimate the accuracy of the new method. The tests were carried out on 78 eyes with cataract in different progression state ranging from healthy to above 5 on the LOCS III scale. The residual error of the calibration (i.e. the standard deviation of difference between clinical reference and our algorithmic characterisation) turned out to be [Formula: see text] category on the LOCS III N scale, which approximates the [Formula: see text] precision of classic cataract measurements carried out with the greatest care.

Simulation of relief-type diffractive lenses in ZEMAX using parametric modelling and scalar diffraction.

For the simulation of relief-type diffractive surfaces, an efficient method has been developed and described. Based on zone decomposition, our approach maps the transmitted wavefront by ray tracing, while point spread function/modulation transfer function (PSF/MTF) plots are calculated by scalar diffraction, taking light diffracted into multiple orders into account inherently. Using a parametric user-defined surface, our solution makes the analysis and optimization of diffractive lenses possible directly inside optical design software. Implementation was carried out in ZEMAX in the form of a swift Windows Dynamic Link Library extension using an approximative, non-iterative algorithm. The average computation time increments relative to standard built-in surfaces are 38% and 21% for PSF and MTF calculations, respectively. Application of our method is illustrated by the analysis of diffractive intraocular lenses. For validation, numerical results were compared with analytical formulae and industry-standard measurements. The ray-tracing error caused by our approximation proved to be less than ${7} \cdot {{10}^{ - 6}}$7⋅10-6 wavelength, and the difference from the theoretical MTF calculations is 1%-2%. The RMS difference of the simulated-measured through-focus MTF values at 50 lp/mm is 0.031, equaling ${2}\sigma $2σ measuring accuracy.

Author Correction: Simulation of visual acuity by personalizable neuro-physiological model of the human eye.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Simulation of visual acuity by personalizable neuro-physiological model of the human eye.

We present a model of the whole visual train to estimate an individual's visual acuity based on their eye's physical properties. Our simulation takes into account the optics of the eye, neural transmission and noise, as well as the recognition process. Personalized input data are represented by the ocular wavefront aberration and pupil diameter, both either coming from in vivo measurements of a subject or being produced by optical design software using a schematic eye. This flexibility opens the door to a broad range of potential applications, such as objective visual acuity measurements and intraocular lens design. Our algorithm contains only two adjustable neural parameters: additive noise σ, and discrimination range δρ, with their values being experimentally calibrated by fitting the results of simulations to the outcome of real acuity tests performed on healthy young subjects with normal vision (visual acuity: 0…-0.3 logMAR range). It was established that by using fixed values of σ = 0.10 and δρ = 0.0025 for each person examined, the residual of the acuity simulations averaged over the calibration group reached its minimum at 0.045 logMAR.

Application of Correlation-Based Scoring Scheme for Visual Acuity Measurements in the Clinical Practice.

PURPOSE: Visual acuity tests are generally performed by showing eye charts to the subjects and registering their correct/incorrect identifications for the presented optotypes. We recently developed a correlation-based scoring method that significantly reduces the statistical error associated with relative letter legibility. In this paper, our purpose was to demonstrate the advantages and clinical utility of our scoring scheme compared to standard methods. METHODS: We developed a new computer-controlled measurement setup aligned with the ophthalmological standard. With this system, we presented the application of our correlation-based scoring in conventional clinical environment for 25 subjects and estimated the systematic error of the obtained acuity values. A separate experiment was performed by 14 additional subjects to reveal the test-retest variability of the new scoring method. RESULTS: The average systematic error relative to standard probability-based scoring is 0.01 logMAR over the examined subject group. Application of the correlation-based scheme when used in clinical environment with five letters per size decreases the repeatability error by ∼20% and increases diagnosis time by ∼10%. CONCLUSIONS: The new scoring scheme is directly applicable in clinical practice providing unbiased results with improved repeatability compared to standard visual acuity measurements. It reduces test-retest variability by the same amount as if the number of letters was doubled in traditional tests. TRANSLATIONAL RELEVANCE: Our new method is a promising alternative to conventional acuity tests in cases when high-precision measurements are required, for example evaluating implanted intraocular lenses, testing subjects with retinal diseases or cataract, and refractive surgery candidates.

Correlation-based evaluation of visual performance to reduce the statistical error of visual acuity.

Ophthalmologists evaluate visual acuity tests by the number of correctly recognized optotypes (usually letters) in the different lines of an eye chart. This probability-based scoring results in significant statistical error that can only be decreased by the time-consuming analysis of a larger number of optotypes. In this paper, we present a new, more precise correlation-based scoring method that takes the degree of misidentification into consideration too, rather than the mere fact of it. According to our experimental results, this new method decreases the uncertainty error by 28% if using the same number of optotypes at a given letter size or requires half the optotype number to produce the same error as that of probability-based scoring.

Mechanism of aberration balance and the effect on retinal image quality in keratoconus: optical and visual characteristics of keratoconus.

PURPOSE: To evaluate ocular wavefront aberrations in keratoconus and describe their effect on visual quality. SETTING: Department of Ophthalmology Semmelweis University, Budapest, Hungary. DESIGN: Case-control study. METHODS: Ocular aberrations over a 4.5 mm pupil were measured with a Hartmann-Shack sensor in eyes with keratoconus or subclinical keratoconus or of refractive surgery candidates with normal corneas. Visual quality metrics were calculated using an optical design program. The correlation between Zernike polynomials was evaluated using correlation analysis. Predictors of subclinical keratoconus and keratoconus among ocular aberrations were evaluated. Visual quality (point-spread function, retinal spot radius, Strehl ratio) between groups was compared. RESULTS: Horizontal and vertical coma were significant predictors of subclinical keratoconus (P<.05, r(2)=0.85) and oblique astigmatism and vertical coma of keratoconus (P<.05, r(2)=0.64). Spot radius (P<.05, r(2)=0.66) and the Strehl ratio (P<.05, r(2)=0.64) were significant discriminators in all groups. On correlation analysis, interactions of ocular aberrations were different in keratoconus eyes than in control eyes. In keratoconus eyes, there was a negative correlation between defocus and spherical aberration (r = -0.41) and between astigmatism and secondary astigmatism (r=-0.68). In contrast, spherical aberration correlated positively with tetrafoil (r=0.47) and the positive correlation between vertical coma and vertical tilt decreased (r=0.67 versus r=0.34). CONCLUSION: Image quality in keratoconus was significantly decreased at equal levels of total root mean square error. A combination of ocular aberrations in eyes with keratoconus decreased image quality.

Hologram positioning servo for phase-encoded holographic data storage systems.

We propose a method using phase encryption and hologram multiplexing to encode positional information into the hologram, which can be used during readout to find the correct position of the reference beam. We also include a method to align the position of the phase code in the reference beam during readout, with which we achieved approximately 1/100 hologram size (4.4 microm) precision electronically, without the need of a precise mechanical hologram positioning device. We prove the feasibility of the method with experiments.

Hybrid multinary modulation using a phase modulating spatial light modulator and a low-pass spatial filter.

We propose a method for performing binary intensity and continuous phase modulation of beams with a spatial light modulator (SLM) and a low-pass spatial filtering 4-f system. With our method it is possible to avoid the use of phase masks in holographic data storage systems or to enhance the phase encoding of the SLM by making it capable of binary amplitude modulation. The data storage capabilities and the limitations of the method are studied.

Association between heat shock protein 70s and toll-like receptor polymorphisms with long-term renal allograft survival.

Long-term renal allograft survival has not improved significantly in recent years and only a minority of grafts survives for more than 15 years. To evaluate the association between HSPA1A G(190)C, HSPA1B A(1267)G and TLR4 A(299)G polymorphisms and allograft survival we analyzed DNA of patients with long-term renal graft function over 15 years (Tx15), consecutively transplanted recipients (Tx), patients with acute rejection and healthy controls. HSPA1B (1267)AA was less prevalent in Tx versus Tx15 (P = 0.02) and versus controls (P = 0.004). HSPA1B (1267)GG was more frequent in Tx versus Tx15 (P = 0.005) and versus controls (P = 0.002). HSPA1B (1267)G allele occurred more often in Tx versus Tx15 (P = 0.03), and versus controls (P = 0.02). TLR4 (299)AG genotype prevalence was increased in Tx15 versus Tx (P = 0.02), while TLR4 (299)G allele was more frequent in Tx15 versus Tx (P = 0.02). The increased frequency of HSPA1B (1267)AA and TLR4 (299)AG genotypes in Tx15 group indicates that better cytoprotective functions in HSPA1B (1267)AA and reduced proinflammatory response in TLR4 (299)AG carriers might have improved renal allograft survival.

[Potential consequences of the sudden postnatal drop of estrogen levels in preterm neonates]. / Az in utero magas ösztrogénszint hirtelen megszúnésének lehetséges hatásai koraszülöttekben.

Estrogens have profound effects on bone- and lipid homeostasis, modulate immune functions and play a major role in the regulation of the development and function of central nervous system, cardiovascular system and respiratory system. They induce hepatic protein production. There is a strong connection between estrogens and several hormone systems including growth hormone--IGF axis and renin-angiotensin system. The extragenital effects of estrogens are probably more evident in the fetus than in fertile women. However, direct data are not available because of the lack of estrogen-deficient pregnancy models. Theoretically, in immature infants the premature cessation of in utero high estrogen levels is associated with the progression of perinatal acute complications. The volume of uterus in female premature infants is lower than in term newborns, the plasma levels of atherogen lipids are high, osteopenia due to inadequate bone acquisition is frequent. Inflammatory complications are common. Recently, the physiological effects of estrogen- and progesterone supplementation of premature infants have been evaluated in a pilot study. The preliminary results indicate, that the risk of bronchopulmonary dysplasia, osteopenia might be decreased in treated infants. Further studies are needed to confirm the effectivity and long term safety of estrogen supplementation of preterm neonates.

[New clinical entity in perinatology: fetal inflammatory response syndrome]. / Uj klinikai entitás a perinatológiában: a magzati gyulladásos válaszreakció szindróma.

In spite of the adequate therapy serious inflammatory complications affect the majority of preterm neonates. Recently, the role of fetal inflammatory response syndrome has been emerged as a possible mechanism. This new clinical entity is characterised by the generalised activation of fetal immune system which is often the result of chorioamnionitis. The level of inflammatory cytokines (interleukin-6) often elevates in fetuses affected by this syndrome. Elevated cytokine levels induce the infiltration of inflammatory cells into the amnion and activate matrix metalloproteases in the fetus. As a result, preterm birth occurs. The high levels of inflammatory cytokines in the fetus are associated with the development of bronchopulmonary dysplasia and periventricular leukomalacia in the newborn. Except the elevation of fetal interleukin-6 levels there is still no specific clinical or laboratory sign of the fetal inflammatory response syndrome. Further investigation is needed to understand the importance of this syndrome in the development of perinatal complications and to develop specific laboratory tests for the early recognition.