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PURPOSE: This article introduces the Pentacam® Cornea OCT (optical coherence tomography). This advanced corneal imaging system combines rotating ultra-high-resolution spectral domain OCT with sub- 2-micron axial resolution and Scheimpflug photography. The purpose of this study is to present the first experience with the instrument and its potential for corneal diagnostics, including optical biopsy. METHODS: In this prospective study, the Pentacam® Cornea OCT was used to image the corneas of seven patients. The novel wide-angle pericentric scan system enables optimal OCT imaging performance for the corneal layer structure over the entire width of the cornea, including the limbal regions. A detailed analysis of the resulting images assessed the synergism between the OCT and Scheimpflug photography. RESULTS: The Pentacam® Cornea OCT demonstrated significantly improved image resolution and ability to individualize corneal layers with high quality. There is a synergism between the OCT high-definition signal to individualize details on the cornea and Scheimpflug photography to detect and quantify corneal scattering. The noncontact exam was proven safe, user-friendly, and effective for enabling optical biopsy. CONCLUSIONS: Pentacam® Cornea OCT is an advancement in corneal imaging technology. The ultra-high-resolution spectral domain OCT and Scheimpflug photography provide unprecedented detail and resolution, enabling optical biopsy and improving the understanding of corneal pathology. Further studies are necessary to compare and analyze the tomographic reconstructions of the cornea with the different wavelengths, which may provide helpful information for diagnosing and managing corneal diseases.

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The Ediacaran-Cambrian transition documents a critical stage in the diversification of animals. The global fossil record documents the appearance of cloudinomorphs and other shelled tubular organisms followed by non-biomineralized small carbonaceous fossils and by the highly diversified small shelly fossils between ~ 550 and 530 Ma. Here, we report diverse microfossils in thin sections and hand samples from the Ediacaran Bocaina Formation, Brazil, separated into five descriptive categories: elongate solid structures (ES); elongate filled structures (EF); two types of equidimensional structures (EQ 1 and 2) and elongate hollow structures with coiled ends (CE). These specimens, interpreted as diversified candidate metazoans, predate the latest Ediacaran biomineralized index macrofossils of the Cloudina-Corumbella-Namacalathus biozone in the overlying Tamengo Formation. Our new carbonate U-Pb ages for the Bocaina Formation, position this novel fossil record at 571 ± 9 Ma (weighted mean age). Thus, our data point to diversification of metazoans, including biomineralized specimens reminiscent of sections of cloudinids, protoconodonts, anabaritids, and hyolithids, in addition to organo-phosphatic surficial coverings of animals, demonstrably earlier than the record of the earliest known skeletonized metazoan fossils.

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INTRODUCTION: The study aims to demonstrate and estimate the prevalence of clinical corneal ectasia and keratoconus (KC) in patients with relatively low keratometry (low-K KC). METHODS: In a retrospective, analytical, and non-interventionist study, one eye was randomly selected from 1054 patients from the original Tomographic Biomechanical Index (TBIv1) study and the external validation (from Rio de Janeiro, Brazil, and Milan, Italy clinics). Patients were stratified into three groups. Group 1 included 736 normal patients, and groups 2 and 3 included 318 patients with clinical KC in both eyes, divided into low-K KC (90 patients) and high-K KC (228 patients), respectively. All patients underwent a comprehensive ophthalmological evaluation along with Pentacam and Corvis ST (Oculus, Wetzlar, Germany) examinations. Cases with maximum mean zone 3 mm keratometry (Kmax zone mean 3 mm) lower than 47.6 diopters (D) were considered as low-keratometry keratoconus, and cases with Kmax zone mean 3 mm higher than 47.6 D were regarded as high-keratometry keratoconus. RESULTS: Ninety (28.30%) of the 318 KC group presented ectasia with low-keratometric values (low-Kmax). The average age in the normal group was 39.28 years (range 6.99-90.12), in the low-Kmax KC group it was 37.49 (range 13.35-78.45), and in the high-Kmax KC group it was 34.22 years (range 12.7-80.34). Mean and SD values and median (range), respectively, of some corneal tomographic and biomechanical parameters evaluated from the low-Kmax KC group were as follows: Belin-Ambrósio enhanced ectasia display (BAD-D) 3.79 ± 1.62 and 3.66 (0.83-9.73); Pentacam random forest index (PRFI) 0.78 ± 0.25 and 0.91 (0.05-1); corneal biomechanical index (CBI) 0.58 ± 0.43 and 0.75 (0-1); TBI 0.93 ± 0.17 and 1 (0.35-1); and stiffness parameter at A1 (SP-A1) 86.16 ± 19.62 and 86.05 (42.94-141.66). CONCLUSION: Relatively low keratometry, with a Kmax lower than 47.6 D, can occur in up to 28.30% of clinical keratoconus. These cases have a less severe presentation of the disease. Future studies involving larger populations and prospective designs are necessary to confirm the prevalence of keratoconus with low keratometry and define prognostic factors in such cases.

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Different diagnostic approaches for ectatic corneal diseases (ECD) include screening, diagnosis confirmation, classification of the ECD type, severity staging, prognostic evaluation, and clinical follow-up. The comprehensive assessment must start with a directed clinical history. However, multimodal imaging tools, including Placido-disk topography, Scheimpflug three-dimensional (3D) tomography, corneal biomechanical evaluations, and layered (or segmental) tomography with epithelial thickness by optical coherence tomography (OCT), or digital very high-frequency ultrasound (dVHF-US) serve as fundamental complementary exams for measuring different characteristics of the cornea. Also, ocular wavefront analysis, axial length measurements, corneal specular or confocal microscopy, and genetic or molecular biology tests are relevant for clinical decisions. Artificial intelligence enhances interpretation and enables combining such a plethora of data, boosting accuracy and facilitating clinical decisions. The applications of diagnostic information for individualized treatments became relevant concerning the therapeutic refractive procedures that emerged as alternatives to keratoplasty. The first paradigm shift concerns the surgical management of patients with ECD with different techniques, such as crosslinking and intrastromal corneal ring segments. A second paradigm shift involved the quest for identifying patients at higher risk of progressive iatrogenic ectasia after elective refractive corrections on the cornea. Beyond augmenting the sensitivity to detect very mild (subclinical or fruste) forms of ECD, ectasia risk assessment evolved to characterize the inherent susceptibility for ectasia development and progression. Furthermore, ectasia risk is also related to environmental factors, including eye rubbing and the relational impact of the surgical procedure on the cornea.

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This article presents an experimental study to analyze the mechanical properties of a soil stabilized with ordinary Portland cement (OPC) under a sustainable approach consisting of a significant substitution of OPC for sugarcane bagasse ash (SCBA) to reduce the quantity of cement used in the stabilization, reaching the necessary mechanical requirements for its use as a subgrade layer. Soil specimens were elaborated with 3%, 5%, and 7% OPC as a stabilizing agent by weight of the soil. These mixtures were then partially substituted with 25%, 50%, and 75% SCBA, with these percentages being by weight of the stabilizer (OPC). Compaction, compressive strength, and California bearing ratio (CBR) tests were performed to evaluate the mechanical properties of the specimens. The results indicate that a 25% substitution of OPC by SCBA shows a similar performance to the mixture with only Portland cement, so a reduction in OPC use can be made. Further, with a substitution of 100% OPC by SCBA, the CBR of natural soil without stabilizers is improved.

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In post-tensioned systems, grouts act as a last line of defense to prevent the penetration of harmful compounds such as chlorides, moisture and other substances that cause corrosion in the prestressing steel. For this reason, improving grouts results in the enhancement of the overall durability of the structure. In this study, the physical properties of grouts with basalt microfiber additions in the amounts of 0.03, 0.07 and 0.10% with respect to the mix volume were evaluated. The fresh properties included flowability and unit mass. Specimens were fabricated to evaluate drying shrinkage, compressive strength, air permeability and rapid permeability to chloride ions. The incorporation of basalt microfibers showed a beneficial effect on the physical properties of the grout by increasing the drying shrinkage resistance and decreasing the permeability compared to the reference mix and two commercial dry prepackaged grouts. The optimal grout mix was the one with a percentage of basalt microfibers of 0.10%, which decreased drying shrinkage by 15.98% at 14 days compared to the reference mix, and permeability to chloride ions decreased by 10.82% compared to the control mix.

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Purpose: To prospectively review the importance of biomechanical assessment in the screening, diagnosis, prognosis, individualized planning, and clinical follow-up for ectatic corneal diseases.Methods: We demonstrate two commercially available devices to assess the corneal biomechanics in vivo, the Ocular Response Analyzer (ORA, Reichester, NY, USA) and the Corvis ST (Oculus, Wetzlar, Germany). Novel devices have been demonstrated to provide in vivo biomechanical measurements, including Brillouin optical microscopy and OCT elastography. Conclusion: The integration of biomechanical data and other data from multimodal refractive imaging using artificial intelligence demonstrated the ability to enhance accuracy in diagnosing ectatic corneal diseases.

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RESUMO Objetivo Avaliar a precisão da tomografia corneana com imagens de Scheimpflug (Pentacam® AXL, OCULUS, Wetzlar, Alemanha) nos padrões de escaneamento com 25 e 50 imagens, verificando sua repetibilidade e reprodutibilidade em olhos normais, com ceratocone e com ceratocone após crosslinking. Métodos Estudo prospectivo, transversal, misto, no qual foram incluídos os pacientes que tinham córneas normais, ou com ceratocone; e não tinham realizado cirurgias corneanas, com exceção do crosslinking. Foram excluídos os pacientes que tivessem realizado outras cirurgias, como implante de anel intracorneano ou transplante de córnea. Foram realizadas três medidas com 25 imagens e três medidas com 50 imagens em cada olho incluído no estudo. Resultados O estudo avaliou 54 olhos de 41 pacientes. Destes, dez (18,52%) olhos eram com córneas normais e sem cirurgia ocular prévia aleatoriamente selecionados de 5 pacientes; 22 (40,74%) olhos aleatoriamente selecionados de 18 pacientes com ceratocone, sem cirurgia ocular prévia; e 22 (40,74%) olhos com ceratocone de 18 pacientes operados por crosslinking. No estudo da repetibilidade, percebemos uma maior variação de valores em todos os índices nos pacientes com ceratocone comparados aos de pacientes com olhos normais, em grande parte dos parâmetros analisados. Conclusão Não houve diferença significativa entre os métodos de escaneamento por 25 e 50 imagens, sendo o escaneamento por 25 imagens mais conveniente. A presença de ceratocone teve impacto negativo na repetibilidade de ambos os tipos de exame, e foi grande a concordância entre os métodos nos três grupos estudados. O coeficiente de repetibilidade permite considerar a relevância clínica dos dados para avaliar a progressão de ceratocone.

ABSTRACT Objective To evaluate the accuracy of corneal tomography with Scheimpflug images (Pentacam® AXL, OCULUS, Wetzlar, Germany) in scanning patterns with 25 and 50 images, by analyzing their repeatability and reproducibility in normal eyes, eyes with keratoconus and with keratoconus after crosslinking. Methods Prospective, cross-sectional, mixed study including patients who had normal corneas, or who had keratoconus, who had not undergone corneal surgery, with the exception of crosslinking. Patients who had undergone surgery for intracorneal ring implantation or corneal transplantation were excluded. Three measurements were performed with 25 images and three measurements were performed with 50 images on each eye included in the study. Results The study evaluated a total of 54 eyes of 41 patients. Of these, 10 (18.52%) eyes had normal corneas, without previous eye surgery, 22 (40.74%) were eyes with keratoconus, without previous eye surgery, and 22 (40.74%) were eyes with keratoconus, with crosslinking for keratoconus. In the study of repeatability, we noticed a greater variation of values in all indices in patients with KC compared to those with normal eyes, in most of the parameters analyzed. Conclusion There is no significant difference between the scanning methods with 25 and 50 images. However, 25 scans has advantages that make it the main method suggested. The presence of keratoconus has a negative impact on the repeatability of both types of examination, and there is great agreement between the methods in the three groups studied. The high repeatability coefficient in some parameters suggests that these data should be used with care in the assessment of keratoconus progression.

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There are different fundamental diagnostic strategies for patients with ectatic corneal diseases (ECDs): screening, confirmation of the diagnosis, classification of the type of ECD, severity staging, prognostic assessment, and clinical follow-up. The conscious application of such strategies enables individualized treatments. The need for improved diagnostics of ECD is related to the advent of therapeutic refractive procedures that are considered prior to keratoplasty. Among such less invasive procedures, we include corneal crosslinking, customized ablations, and intracorneal ring segment implantation. Besides the paradigm shift in managing patients with ECD, enhancing the sensitivity to detect very mild forms of disease, and characterizing the inherent susceptibility for ectasia progression, became relevant for identifying patients at higher risk for progressive iatrogenic ectasia after laser vision correction (LVC). Moreover, the hypothesis that mild keratoconus is a risk factor for delivering a baby with Down's syndrome potentially augments the relevance of the diagnostics of ECD. Multimodal refractive imaging involves different technologies, including Placido-disk corneal topography, Scheimpflug 3-D tomography, segmental or layered tomography with layered epithelial thickness using OCT (optical coherence tomography), and digital very high-frequency ultrasound (VHF-US), and ocular wavefront. Corneal biomechanical assessments and genetic and molecular biology tests have translated to clinical measurements. Artificial intelligence allows for the integration of a plethora of clinical data and has proven its relevance in facilitating clinical decisions, allowing personalized or individualized treatments.

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Depending on the morphology of the natural fibers, they can be used as reinforcement to improve flexural strength in cement-based composites or as aggregates to improve thermal conductivity properties. In this last aspect, hemp, coconut, flax, sunflower, and corn fibers have been used extensively, and further study is expected into different bioaggregates that allow diversifying of the raw materials. The objective of the research was to develop plant-based concretes with a matrix based on Portland cement and an aggregate of Agave salmiana (AS) leaves, obtained from the residues of the tequila industry that have no current purpose, as a total replacement for the calcareous aggregates commonly used in the manufacturing of mortars and whose extraction is associated with high levels of pollution, to improve their thermal properties and reduce the energy demand for air conditioning in homes. Characterization tests were carried out on the raw materials and the vegetal aggregate was processed to improve its compatibility with the cement paste through four different treatments: (a) freezing (T/C), (b) hornification (T/H), (c) sodium hydroxide (T/NaOH), and (d) solid paraffin (T/P). The effect of the treatments on the physical properties of the resulting composite was evaluated by studying the vegetal concrete under thermal conductivity, bulk density, and compressive strength tests with a volumetric ratio between the vegetal aggregate and the cement paste of 0.36 and a water/cement ratio of 0.35. The hornification treatment showed a 15.2% decrease in the water absorption capacity of the aggregate, resulting in a composite with a thermal conductivity of 0.49 W/mK and a compressive strength of 8.66 MPa, which allows its utilization as a construction material to produce prefabricated blocks.

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PURPOSE: To evaluate the characteristics of corneal material properties in healthy individuals and keratoconic patients using the stress-strain index (SSI). SETTING: Vincieye Clinic in Milan, Italy, and Instituto de Olhos Renato Ambrósio in Rio de Janeiro, Brazil. DESIGN: Retrospective observational cross-sectional study. METHODS: Records of 1221 patients were divided into 3 groups: healthy corneas (n = 728), bilateral keratoconus (KC, n = 388), and very asymmetric ectasia (VAE, n = 105) when patients presented with clinical ectasia in 1 eye and normal topography (VAE-NT) in the fellow eye. All patients were examined with Pentacam HR and Corvis ST. Severity of KC cases was stratified according to the Pentacam topographic KC classification. The SSI distribution across the different groups and its correlation with age, biomechanically corrected intraocular pressure (bIOP), and central corneal thickness (CCT) were assessed. RESULTS: A statistically significant difference between healthy individuals and each of the keratoconic groups ( P < .001) was observed, and a progressive reduction in the SSI was observed across the groups. A significant correlation was observed between the SSI and age in all groups ( P < .010) but KC severe subgroup ( P = .361). No correlation between the SSI and bIOP and CCT was observed in all KC subgroups and VAE-NT groups ( P > .050). Among healthy eyes, there was only a mild correlation between the SSI and bIOP ( R = 0.12, P = .002) and CCT ( R = 0.13, P = .001). CONCLUSIONS: This study estimates the in vivo corneal material properties in healthy individuals and patients with KC using a new method. The SSI showed a progressive deterioration within the advance in disease stages while being relatively independent of bIOP and CCT but positively correlated with age.

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Concrete barely possesses tensile strength, and it is susceptible to cracking, which leads to a reduction of its service life. Consequently, it is significant to find a complementary material that helps alleviate these drawbacks. The aim of this research was to determine analytically and experimentally the effect of the addition of the steel fibers on the performance of the post-cracking stage on fiber-reinforced concrete, by studying four notch-to-depth ratios of 0, 0.08, 0.16, and 0.33. This was evaluated through 72 bending tests, using plain concrete (control) and fiber-reinforced concrete with volume fibers of 0.25% and 0.50%. Results showed that the specimens with a notch-to-depth ratio up to 0.33 are capable of attaining a hardening behavior. The study concludes that the increase in the dosage leads to an improvement in the residual performance, even though an increase in the notch-to-depth ratio has also occurred.

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Corneal ectasia is a complication of refractive surgery, and keratoconus is a contraindication to this type of procedure. Surface ablation may be an option for selected cases of mild keratoconus, with patient education being fundamental to this treatment as well as a complete evaluation of the cornea and optical properties of the patient. Here we report the clinical outcome of a patient 15 years after advanced surface ablation in a case of mild (fruste) keratoconus.

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Corneal biomechanics has been a hot topic for research in contemporary ophthalmology due to its prospective applications in diagnosis, management, and treatment of several clinical conditions, including glaucoma, elective keratorefractive surgery, and different corneal diseases. The clinical biomechanical investigation has become of great importance in the setting of refractive surgery to identify patients at higher risk of developing iatrogenic ectasia after laser vision correction. This review discusses the latest developments in the detection of corneal ectatic diseases. These developments should be considered in conjunction with multimodal corneal and refractive imaging, including Placido-disk based corneal topography, Scheimpflug corneal tomography, anterior segment tomography, spectral-domain optical coherence tomography (SD-OCT), very-high-frequency ultrasound (VHF-US), ocular biometry, and ocular wavefront measurements. The ocular response analyzer (ORA) and the Corvis ST are non-contact tonometry systems that provide a clinical corneal biomechanical assessment. More recently, Brillouin optical microscopy has been demonstrated to provide in vivo biomechanical measurements. The integration of tomographic and biomechanical data into artificial intelligence techniques has demonstrated the ability to increase the accuracy to detect ectatic disease and characterize the inherent susceptibility for biomechanical failure and ectasia progression, which is a severe complication after laser vision correction.

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The past two decades have seen a proliferation in bioarchaeological literature on the identification of scurvy, a disease caused by chronic vitamin C deficiency, in ancient human remains. This condition is one of the few nutritional deficiencies that can result in diagnostic osseous lesions. Scurvy is associated with low dietary diversity and its identification in human skeletal remains can provide important contextual information on subsistence strategy, resource allocation, and human-environmental interactions in past populations. A large and robust methodological body of work on the paleopathology of scurvy exists. However, the diagnostic criteria for this disease employed by bioarchaeologists have not always been uniform. Here we draw from previous research on the skeletal manifestations of scurvy in adult and juvenile human skeletal remains and propose a weighted diagnostic system for its identification that takes into account the pathophysiology of the disease, soft tissue anatomy, and clinical research. Using a sample of individuals from the prehistoric Atacama Desert in Northern Chile, we also provide a practical example of how diagnostic value might be assigned to skeletal lesions of the disease that have not been previously described in the literature.

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PURPOSE: To identify the relative positions of geometrical and visual axes of the eye and present a method to locate the visual center when the geometrical axis is taken as a reference. METHODS: Topography elevation data was collected using a Pentacam HR ® topographer from 2040 normal eyes of 1020 healthy participants in Brazil, China and Italy. A three-dimensional, rotation algorithm, a first-order Zernike polynomial fit and a nonlinear least-squares error function was used within an optimization function to locate the geometrical axis and the visual center of each eye. RESULTS: The right eyes of participants were significantly more tilted than left eyes throughout the topography scanning process (p < 0.001). The visual centers were always located in the nasal-superior quadrant, although the visual centers of fellow eyes were not symmetrically located. Mean distances between the visual center and the geometrical center in right eyes were 0.8 ± 0.29 mm, 0.56 ± 0.18 mm and 0.91 ± 0.34 mm among Brazilian, Chinese and Italian participants, respectively, and located at angular positions of 38.7 ± 24.5°, 23.0 ± 29.8° and 23.1 ± 28.1° from the nasal side. However, in left eyes, mean distances were 0.76 ± 0.33 mm, 0.45 ± 0.12 mm and 0.75 ± 0.33 mm at polar angles from the nasal side of 59.3 ± 29.0°, 50.6 ± 44.5° and 61.8 ± 34.1°, respectively. CONCLUSIONS: Fellow eyes do not perform similarly during the fixation process, with right eyes tending to tilt more than left eyes, and the visual centers of the fellow eyes positioned differently relative to the geometrical centers.

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AIMS AND OBJECTIVES: The transition to an agricultural economy is often presumed to involve an increase in female fertility related to changes in weaning practice. In particular, the availability of staple crops as complementary foods is hypothesized to allow earlier weaning in agricultural populations. In this study, our primary aim is to explore whether this model fits the agricultural transition in the Atacama Desert using incremental isotopic analysis. A secondary aim of this study is to identify isotopic patterns relating to weaning, and assess how these may be differentiated from those relating to early life stress. MATERIALS AND METHODS: We use incremental isotopic analysis of dentine to examine changes in δ15 N and δ13 C values from infancy and childhood in sites of the Arica region (n = 30). We compare individuals from pre-agricultural and agricultural phases to establish isotopic patterns and relate these patterns to maternal diet, weaning trajectory and physiological stress. RESULTS: We find that there is no evidence for systematic temporal or geographic variation in incremental isotopic results. Instead, results from all time periods are highly variable, with weaning completed between 1.5 and 3.5 years. Characteristics of the incremental profiles indicate that both in utero and postnatal stress were a common part of the infant experience in the Atacama. DISCUSSION: In the Atacama Desert it appears that the arrival of agricultural crops did not result in uniform shifts in weaning behavior. Instead, infant and child diet seems to have been dictated by the broad-spectrum diets of the mothers, perhaps as a way of mitigating the stresses of the harsh desert environment.

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Studies of contemporary populations have demonstrated an association between decreased dietary diversity due to resource scarcity or underutilization and an increase in diseases related to poor micronutrient intake. With a reduction of dietary diversity, it is often the women and children in a population who are the first to suffer the effects of poor micronutrient status. Scurvy, a disease of prolonged vitamin C deficiency, is a micronutrient malnutrition disorder associated with resource scarcity, low dietary diversity, and/or dependence on high carbohydrate staple-foods. The aim of this paper is to assess the potential impact of nutritional transition on the prevalence of diseases of nutritional insufficiency in an archaeological sample. Here, we report palaeopathological findings from an Early Formative Period transitional site located in coastal Northern Chile (Quiani-7). The subadult cohort from this site is composed of four perinates who exhibit a number of non-specific skeletal changes suggestive of a systemic pathological condition. One of these is associated with an adult female exhibiting diagnostic skeletal lesions of scurvy. We argue that the lesions exhibited by these perinates may represent maternal transmission of vitamin C deficiency but acknowledge that there are difficulties in applying current diagnostic criteria for scurvy to individuals this young.

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PURPOSE: To assess the repeatability and reproducibility of dynamic corneal response parameters measured by the Corvis ST (Oculus, Wetzlar, Germany). METHODS: One eye randomly selected from 32 healthy volunteers was examined by the Corvis ST. Three different devices were used in an alternated random order for taking three measurements at each device in each subject. Standard intraocular pressure (IOP), the biomechanical-compensated IOP (bIOP), and DCR parameters were evaluated. The within-subject standard deviation (ζw) and coefficient of variation (CV) were assessed. RESULTS: Regarding pressure indices, the ζw was below 1 mmHg for repeatability (0.98 for IOP and 0.89 for bIOP) and the CV was 6.6% for IOP and 6.1% for bIOP. For reproducibility, the ζw was around 1 mmHg (1.12 for IOP and 1.05 for bIOP) and the CV was 7.6% for IOP and 7.1% for bIOP. Most of DCR indices presented CV for repeatability below 4%. For reproducibility, the CV of most of the indices were below 6%. The deformation amplitude (DA) ratio in 1 mm and integrated radius were below 4% (1.2% and 3.8%, resp.). CONCLUSIONS: The Corvis ST showed good precision (repeatability and reproducibility) for IOP measurements and for DCR in healthy eyes.