PURPOSE: To compare the accuracy of intraocular lens power calculation formulas and to examine the correlation of this exactness with the axial length for eyes shorter than 22.00 mm Methods: The data of hyperopic patients who underwent uneventful phacoemulsification between October 2015 and June 2019 were reviewed. The intraocular lens power for each patient was calculated using 6 formulas (Holladay1, SRK/T, Hoffer Q, Holladay 2, Haigis and Barrett Universal II) before cataract surgery. Postoperative refraction was measured, and refractive prediction error was calculated 3 months after phacoemulsification. The correlation between axial length and absolute error was evaluated. RESULTS: Fifty-six patients (62 eyes) whose ocular axial length ranged between 20.58 mm and 21.97 mm were included in the study. The Hoffer Q formula achieved the lowest mean absolute error of 0.09 (±0.08 D). A significant correlation for the Hoffer Q (ρ = -0.329, p = 0.009) and the SRK/T (ρ = 0.321, p = 0.011) formula was observed. CONCLUSIONS: 1. The Hoffer Q formula obtained the lowest absolute error and was recommended for intraocular lens power calculation for eyeballs with axial length shorter than 22.0 mm. 2. The correlation between axial length and absolute error is a factor which should be considered when calculating intraocular lens power.
- Klíčová slova
- Hoffer Q formula, Phacoemulsification, hyperopia, intraocular lenses,
- MeSH
- biometrie metody MeSH
- fakoemulzifikace * MeSH
- implantace nitrooční čočky MeSH
- lidé MeSH
- nitrooční čočky * MeSH
- optika a fotonika MeSH
- refrakce oka MeSH
- refrakční vady * MeSH
- retrospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this research was to evaluate mutual interchangeability of four principally different biometric instrumental techniques designed for objective measurement of changes in the physical, mechanical, and topographical properties of the skin surface treated with commercial antiaging cosmetic products with hyaluronic acid. The following instrumental devices were used: Visioscope PC 35, Corneometer Multiprobe Adapter MPA 6, Reviscometer RVM 600, and 3D scanner Talysurf CLI 500. The comparison of the individual methods was performed using cluster analysis. The study involved 25 female volunteers aged 40-65. Measurements were taken before and after 30 daily in vivo applications of an antiaging preparation to the skin surface in the periorbital area. A slight reduction in skin surface roughness was recorded in 55% of the volunteers. On the contrary, a worsening from their initial states was detected in 25% of the subjects, while for 20%, no significant change was reported. Cluster analysis confirmed that the mentioned methodologies can be divided into two basic clusters, namely, a cluster of methods recording the changes in skin relief by means of optical techniques, and a cluster of methods investigating changes in hydration and anisotropy. In practice, the techniques in different clusters are not interchangeable and should be assessed separately.
- MeSH
- biometrie metody MeSH
- chemické jevy * MeSH
- dospělí MeSH
- kosmetické přípravky aplikace a dávkování MeSH
- kůže účinky léků MeSH
- kyselina hyaluronová aplikace a dávkování MeSH
- lidé středního věku MeSH
- lidé MeSH
- povrchové vlastnosti * MeSH
- viskosuplementy aplikace a dávkování MeSH
- zdraví dobrovolníci pro lékařské studie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kosmetické přípravky MeSH
- kyselina hyaluronová MeSH
- viskosuplementy MeSH
UNLABELLED: This paper describes design and construction of a new device for automatic capturing of eye retina and iris. This device has two possible ways of utilization - either for biometric purposes (persons recognition on the base of their eye characteristics) or for medical purposes as supporting diagnostic device. KEY WORDS: eye retina, eye iris, device, acquisition, image.
PURPOSE: The present study compares accuracy of optical biometry (OB) and ultrasound biometry (UB) based on postoperative best corrected visual acuity (BCVA) results, and assesses the extent of the usage of the measurement methods in current practice. METHODS: 335 eyes in total were operated for cataract at Beskydské oční centrum (Beskydy Eye Centre; BOC), Frýdek-Místek hospital, in the period between 7 February 2007 and 7 April 2010. All patients were examined using both IOL-Master and Ocu-Scan prior to the surgery. All surgeries were performed using microcoaxial phacoemulsification, 2,2 mm incision, implanting IOL AcrySof SP, SPN or SPN IQ. BCVA was examined three months after the surgery. We first calculated medians of anterior-posterior axial length (AL) values measured using both methods; with both the whole set and individual subsets created according to the eye length. Difference between the two methods was calculated in mm. We calculated accurate dioptric power of the IOL, which should have been implanted in the lens bag to ensure postoperative emmetropia, using BCVA results. With each eye, we determined the size of diopter variation of the IOLs dioptric power value for emmetropia determined by an optical biometer from the accurate value of the IOLs dioptric power. Ultrasound biometry results were processed in the same way. The SRK-T formula was used for calculation with each biometry. We also calculated the number of variations above 1 D and 2 D with both biometric methods. RESULTS: The median of axial eye length measured using an optical biometer was 23,08 mm, and the median of axial eye length measured using ultrasound biometry was 22,93 mm. The difference between these values was 0,15 mm (150 microns), which equals the difference between average values of coincident measurement results. Average variation of dioptric power of an implanted IOL from retrospectively established optimum value of the IOLs optical power was 0,40 D lower with optical biometry and 0,16 D lower with ultrasound biometry. In the context of assessing the course of the curves of both methods created using a polynomial graph, this result confirms that the two methods correspond significantly, and therefore selecting any of the methods could not negatively impact determination of the implanted IOLs dioptric power. Comparing the frequency of variations above 1D and 2,0 D with OB and UB from the accurate value of the IOLs dioptric power, we discovered a substantially higher percentage of variations with UB - up to 25 % of the total set above 1,0 D. CONCLUSION: RESULTS of comparing accuracy and comfort of AL measurement with both methods justify unambiguous preference of optical biometry over ultrasound biometry in current practice. If measurement using ultrasound probe is done correctly, results of both methods correspond significantly, and so the methods are mutually replaceable. Using ultrasound biometry is therefore adequate in case optical biometry cannot be used.
- MeSH
- biometrie metody MeSH
- interferometrie metody MeSH
- lidé středního věku MeSH
- lidé MeSH
- nitrooční čočky * MeSH
- reprodukovatelnost výsledků MeSH
- zraková ostrost * MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Studies of the capillary bed characterized by its length or length density are relevant in many biomedical studies. A reliable assessment of capillary length from two-dimensional (2D), thin histological sections is a rather difficult task as it requires physical cutting of such sections in randomized directions. This is often technically demanding, inefficient, or outright impossible. However, if 3D image data of the microscopic structure under investigation are available, methods of length estimation that do not require randomized physical cutting of sections may be applied. Two different rat brain regions were optically sliced by confocal microscopy and resulting 3D images processed by three types of capillary length estimation methods: (1) stereological methods based on a computer generation of isotropic uniform random virtual test probes in 3D, either in the form of spatial grids of virtual "slicer" planes or spherical probes; (2) automatic method employing a digital version of the Crofton relations using the Euler characteristic of planar sections of the binary image; and (3) interactive "tracer" method for length measurement based on a manual delineation in 3D of the axes of capillary segments. The presented methods were compared in terms of their practical applicability, efficiency, and precision.
- MeSH
- biometrie metody MeSH
- kapiláry anatomie a histologie MeSH
- konfokální mikroskopie metody MeSH
- krysa rodu Rattus MeSH
- laboratorní automatizace metody MeSH
- mozek anatomie a histologie MeSH
- zobrazování trojrozměrné metody MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In this paper, we propose a semiautomatic procedure for estimation of particle surface area. It uses automatic segmentation of the boundaries of the particle sections and applies different estimators depending on whether the segmentation was judged by a supervising expert to be satisfactory. If the segmentation is correct the estimate is computed automatically, otherwise the expert performs the necessary measurements manually. In case of convex particles we suggest to base the semiautomatic estimation on the so-called flower estimator, a new local stereological estimator of particle surface area. For convex particles, the estimator is equal to four times the area of the support set (flower set) of the particle transect. We study the statistical properties of the flower estimator and compare its performance to that of two discretizations of the flower estimator, namely the pivotal estimator and the surfactor. For ellipsoidal particles, it is shown that the flower estimator is equal to the pivotal estimator based on support function measurements along four perpendicular rays. This result makes the pivotal estimator a powerful approximation to the flower estimator. In a simulation study of prolate and oblate ellipsoidal particles, the surfactor also performs well for particles which are not extremely elongated. In particular, the surfactor is not very much affected by the singularity in the surfactor formula or by possible inaccuracies in the necessary angle measurements. We also assess the performance of the semiautomatic procedure in a study of somatostatin positive inhibitory interneurons from mice hippocampi. Only 35% of the cells needed to be analysed manually and an important decrease in workload was obtained by using the semiautomatic approach.
- MeSH
- biologické markery metabolismus MeSH
- biometrie metody MeSH
- hipokampus cytologie ultrastruktura MeSH
- interneurony cytologie ultrastruktura MeSH
- myši MeSH
- počítačová simulace MeSH
- povrchové vlastnosti MeSH
- somatostatin metabolismus MeSH
- statistické modely * MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- biologické markery MeSH
- somatostatin MeSH
The study of the complicated architecture of cell space structures is an important problem in biology and medical research. Optical cuts of cells produced by confocal microscopes enable two-dimensional (2D) and three-dimensional (3D) reconstructions of observed cells. This paper discuses new possibilities for direct volume rendering of these data. We often encounter 16 or more bit images in confocal microscopy of cells. Most of the information contained in these images is unsubstantial for the human vision. Therefore, it is necessary to use mathematical algorithms for visualization of such images. Present software tools as OpenGL or DirectX run quickly in graphic station with special graphic cards, run very unsatisfactory on PC without these cards and outputs are usually poor for real data. These tools are black boxes for a common user and make it impossible to correct and improve them. With the method proposed, more parameters of the environment can be set, making it possible to apply 3D filters to set the output image sharpness in relation to the noise. The quality of the output is incomparable to the earlier described methods and is worth increasing the computing time. We would like to offer mathematical methods of 3D scalar data visualization describing new algorithms that run on standard PCs very well.
- MeSH
- biometrie metody MeSH
- lidé MeSH
- teoretické modely * MeSH
- velikost buňky * MeSH
- zobrazování trojrozměrné metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The success of cataract surgery in terms of the postoperative refractive result depends on the calculation of optimal intraocular lens (IOL) power. The accuracy of preoperative measurements (keratometry, biometry) is of a great importance due to the increasing patients' demands on final refractive results. The purpose of this study was to compare the accuracy of contact and immersion techniques of A - scan ultrasound biometry in terms of target postoperative refraction while using the SRK/T formula. The accuracy of the applied biometric techniques was compared by means of the postoperative spherical equivalent (SE). The prospective longitudinal study included 111 non-paired eyes, and the preoperative biometry was performed by means of an OcuScan ultrasound machine (Alcon).The contact technique was used in 48 eyes whereas the immersion technique was employed in 63 eyes.The mean SE in the group measured by the contact technique was -0.13 D, compared to 0.25 D in the group with the applied immersion technique. No statistically significant difference was found in postoperative spherical equivalents while using both biometric techniques (p > 0.1). In this study the choice of a biometric technique had therefore no influence on the predicted postoperative refraction. The results have indicated that the biometric techniques (contact and immersion) are interchangeable in terms of postoperative refractive results.
- MeSH
- biometrie metody MeSH
- extrakce katarakty * MeSH
- implantace nitrooční čočky * metody MeSH
- lidé středního věku MeSH
- lidé MeSH
- nitrooční čočky * MeSH
- oči diagnostické zobrazování MeSH
- refrakce oka * MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ultrasonografie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Publikační typ
- časopisecké články MeSH
- randomizované kontrolované studie MeSH
- srovnávací studie MeSH
Quantification of microvessels in tumors is mostly based on counts of vessel profiles in tumor hot spots. Drawbacks of this method include low reproducibility and large interobserver variance, mainly as a result of individual differences in sampling of image fields for analysis. Our aim was to test an unbiased method for quantifying microvessels in healthy and tumorous lymph nodes of dogs. The endothelium of blood vessels was detected in paraffin sections by a combination of immunohistochemistry (von Willebrand factor) and lectin histochemistry (wheat germ agglutinin) in comparison with detection of basal laminae by laminin immunohistochemistry or silver impregnation. Systematic uniform random sampling of 50 image fields was performed during photo-documentation. An unbiased counting frame (area 113,600 microm(2)) was applied to each micrograph. The total area sampled from each node was 5.68 mm(2). Vessel profiles were counted according to stereological counting rules. Inter- and intraobserver variabilities were tested. The application of systematic uniform random sampling was compared with the counting of vessel profiles in hot spots. The unbiased estimate of the number of vessel profiles per unit area ranged from 100.5 +/- 44.0/mm(2) to 442.6 +/- 102.5/mm(2) in contrast to 264 +/- 72.2/mm(2) to 771.0 +/- 108.2/mm(2) in hot spots. The advantage of using systematic uniform random sampling is its reproducibility, with reasonable interobserver and low intraobserver variance. This method also allows for the possibility of using archival material, because staining quality is not limiting as it is for image analysis, and artifacts can easily be excluded. However, this method is comparatively time-consuming.
- MeSH
- barvení a značení MeSH
- biometrie metody MeSH
- cévní endotel MeSH
- cévy anatomie a histologie patologie MeSH
- imunohistochemie metody MeSH
- lymfatické uzliny anatomie a histologie patologie MeSH
- nádory patologie MeSH
- patologie metody MeSH
- psi MeSH
- reprodukovatelnost výsledků MeSH
- zvířata MeSH
- Check Tag
- psi MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
A new test of the proportional hazards assumption in the Cox model is proposed. The idea is based on Neyman's smooth tests. The Cox model with proportional hazards (i.e. time-constant covariate effects) is embedded in a model with a smoothly time-varying covariate effect that is expressed as a combination of some basis functions (e.g., Legendre polynomials, cosines). Then the smooth test is the score test for significance of these artificial covariates. Furthermore, we apply a modification of Schwarz's selection rule to choosing the dimension of the smooth model (the number of the basis functions). The score test is then used in the selected model. In a simulation study, we compare the proposed tests with standard tests based on the score process.
