Skeleton Density Research Articles

Topographic Quadrant Analysis of Peripapillary Superficial Microvasculature in Optic Disc Drusen.

Background: Limited information is known about the topographic effect of optic disc drusen (ODD) on peripapillary retinal nerve fibers and microvasculature.Objective: This study aims to understand the structural and functional impact of ODD in different quadrants of the optic disc.Methods: We performed a retrospective case-control study of 22 ODD patients (34 eyes) and 26 controls (33 eyes) to compare optical coherence tomography (OCT) retinal nerve fiber layer (RNFL), OCT angiography (OCTA), and corresponding static perimetry mean deviation (MD) calculated using the modified Garway-Heath map in different quadrants of the optic disc. OCTA was analyzed using custom MATLAB script to measure six parameters in a peripapillary annulus with large vessel removal: vessel area density (VAD), vessel skeleton density (VSD), vessel perimeter index (VPI), vessel complexity index (VCI), flux, and vessel diameter index (VDI).Results: Quadrant analysis revealed that OCTA VAD and VCI were significantly decreased in superior, nasal, and inferior but not temporal quadrant. RNFL, VSD, and VPI were significantly impacted only in the superior and nasal quadrants. Corresponding visual field MDs in all ODD eyes were not different in the four quadrants, although eyes with MD equal or worse than −5 dB (32%) had worst visual field corresponding to the superior quadrant of the optic disc (inferior arcuate visual field). Structure-structure comparison of OCT and OCTA showed high correlation of RNFL with multiple OCTA measurements in the superior, nasal, and inferior quadrants but not temporal quadrant. Structure-function analysis revealed significant correlation of VAD and VCI and visual field MD in every quadrant, but RNFL was only significantly correlated in the superior and inferior quadrants.Conclusions: Peripapillary VAD and VCI are decreased in more quadrants than RNFL, supporting the clinical utility of performing OCTA in addition to OCT. Consistent with the most common locations of ODD, five OCT/OCTA measurements (VAD, VCI, RNFL, VSD, VPI) are decreased in the superior and nasal quadrants. OCT/OCTA measurements were significantly impacted in contrast to the relatively mild effect on corresponding visual field MD, consistent with the idea that a decrease in objective structural and vascular measurements occurs without parallel change in subjective visual function in ODD.

Swept-Source OCT Angiographic Characteristics of Treatment-Naïve Nonexudative Macular Neovascularization in AMD Prior to Exudation.

PurposeTo investigate the characteristics of treatment-naïve nonexudative macular neovascularization (MNV) in age-related macular degeneration before the onset of exudation using swept-source optical coherence tomography angiography.MethodsMNV area, choriocapillaris (CC) flow deficits (FDs), vessel area density (VAD), vessel skeleton density (VSD), retinal pigment epithelial detachment (PED) volume, mean choroidal thickness (MCT), and choroid vascularity index (CVI) measurements were assessed at two visits prior to exudation. We compared measurements made at the second visit and the rate of change between visits in eyes with and without exudation. The differences in these parameters between eyes with and without subsequent exudation were summarized with 95% confidence intervals (CIs).ResultsTwenty-one eyes with nonexudative MNV were identified and followed. Nine eyes developed exudation, and 12 eyes did not develop exudation. Differences between these groups of eyes for all parameters tended to be small, and the 95% CIs largely ruled out any substantial differences. Overall, eyes with exudation had 24% smaller VAD, 20% smaller VSD, and 33% smaller PED volume measurements. No noteworthy differences were observed for MNV area, CC FDs, MCT, or CVI measurements.ConclusionsThe onset of exudation was correlated with lesions having less vascularity and smaller PED volume measurements, but measurements of MNV area, CC FDs, MCT, and CVI were not correlated with near-term exudation. Investigations are ongoing to further explore these and other anatomic changes as harbingers of near-term exudation.

A Review of the Multi-Physical Characteristics of Plant Aggregates and Their Effects on the Properties of Plant-Based Concrete

The use of plant aggregates obtained from agricultural co-products mixed with mineral binders to form eco-friendly insulating building materials has been initiated for a few years to bring environmentally friendly solutions to the construction sector. Several studies on different agro-resources have already been carried out, providing various information about the properties of plant aggregates and plant-based concrete. However, the characteristics of the agricultural co-product, which allow it to qualify as a plant aggregate for plant-based concrete, are not yet very clear despite the multitude of data, especially on hemp concrete. Therefore, it is important to gather numerous but very disparate pieces of information available in the literature concerning the properties of plant aggregates and their correlations with composites. This review is based on the results of 120 articles and aims to identify the characterization methods and the multi-physical properties of plant aggregates affecting those of plant-based concrete and to propose additional factors that could influence the properties of the composites. A total of 18 plant aggregates of different origins used for plant-based concrete have been listed in the literature. In France, hemp shiv is the most studied one, but its quantity is quite low unlike cereal or oilseed straws and wood transformation residues. With the existence of several characterization methods, properties like microstructure, particle size distribution, bulk density, water absorption capacity, and chemical composition of aggregates are easily and frequently determined. In contrast, data on the apparent density of particles, the skeleton density, and the hygro-thermal properties of aggregates are rare. The particle size, density, and porosity have been identified as important parameters influencing the properties of the composites. Other parameters related to the behavior of the aggregates under wet compaction and compression of their stacking can also predict the physical and mechanical properties of the obtained plant-based concrete. Dosages of the constituents should be preferred as formulation parameters for future studies assessing the impact of the aggregate properties on the composites.

Choriocapillaris Assessment In Patients Under Mek-Inhibitor Therapy For Cutaneous Melanoma: An Optical Coherence Tomography Angiography Study

ABSTRACT Purpose: The present study investigates by optical coherence tomography angiography (OCTA) the retinal capillary plexus and choriocapillaris flow voids and their possible correlation with MEKAR. Methods: 34 eyes of 17 patients (61.5 years [30.4–77.4]) with stage IV cutaneous melanoma were included prospectively. All patients showed disease progression under treatment with Nivolumab/Ipilimumab and were subsequently treated with the MEK-inhibitor Trametinib 2 mg once daily. At the start and every 6 weeks during follow-up of 4 months, patients underwent a complete ophthalmologic exam, OCTA and when needed fluorescein angiography. Results: Statistical analysis was performed on 17 eyes of 9 patients. Eight patients were excluded due to missing OCTA images or due to drop-out because of decease or change of treatment. Comparing vessel area density (P = .625 and 0.681, respectively), vessel skeleton density (P = .996 and 0.766, respectively) of the superficial and deep capillary plexus, flow void number and total flow void area (mm2 and %) (P = .495; 0.197 and 0.298, respectively) of choriocapillaris slab, before and after treatment, revealed no significant difference. The evolution of choriocapillaris flow void parameter did not significantly differ in patients, who developed MEKAR compared to patients who did not. Conclusion: In patients receiving MEK-inhibitor with and without MEKAR, no significant different characteristics of the retinal capillary plexus and choriocapillaris were found. These data suggest that the development of MEKAR, has no correlation with vascular alteration.

Reactivity of silanol group on siloxane oligomers for designing molecular structure and surface wettability

Molecular structures of siloxane materials should be highly controlled for achieving advanced functionalities. However, it is still difficult to precisely control the structure of siloxane materials by the sol–gel processing. In the present study, we focused on the silanol groups in the intermediate oligomers and resultant siloxane materials as a key structural unit for controlling the molecular structure. Thermal stability and chemical reactivity of silanol groups were found to be highly dependent on the steric effects of the surrounding side chains and siloxane skeletons. The present work suggests that controlling the steric effects around silanol groups in the intermediate oligomers allows modulating the crosslink density of siloxane skeletons. The selective molecular modification tunes the structure and chemical properties of the resultant siloxane materials.

In vivo Noninvasive Imaging and Quantitative Analysis of Iris Vessels

Objective: To quantify the iris vessels and its circadian rhythm in normal eyes. Methods: Fifteen healthy subjects were enrolled in this retrospective, cross-sectional study. All subjects underwent optical coherence tomography angiography (OCTA) and indocyanine green angiography (ICGA) examinations, in which 3/15 completed ICGA and OCTA at the same visit. Upon visit, consecutive OCTA scans were then obtained at the time points of the hour 3:00, 6:00, 8:00, 10:00, 12:00, 14:00, 16:00, 18:00, 20:00, 22:00, and 24:00, respectively. Vessel area density (VAD) and vessel skeleton density (VSD) were used to quantitatively describe the OCTA images of the iris vessels. Results: The VAD and VSD of the iris vessels had circadian rhythm with the highest values observed at about 18:00 h and lowest at 0:00 h; the overall values were relatively stable within the 24 h. The contour analysis suggested that the iris VAD and VSD were correlated with the changes in blood pressure and inversely correlated with the changes in the intraocular pressure. Conclusions: OCTA can be used accurately for quantitative analysis of the iris vessels.

Analysis of macular microvasculature and thickness after ICL implantation in patients with myopia using optical coherence tomography.

To investigate changes in macular vessels and thickness in myopic eyes after intraocular collamer lens (ICL) implantation using quantitative optical coherence tomography angiography (OCTA). This retrospective included 73 myopic eyes of 73 patients (average age, 27.53±6.16y) who underwent ICL implantation (28 eyes were Toric ICL). Axial length (AL), uncorrected visual acuity (UCVA), refractive dioptre (RD), intraocular pressure (IOP) and OCTA were measured and compared with before and 1wk, 1, and 3mo after surgery. OCTA was used to image vessel density (VD) and skeleton density (SD) in both the superficial (SCP) and deep capillary plexus (DCP). Central retinal thickness (CRT) and ganglion cell-inner plexiform layer thickness (GCT) were also measured. Changes between pre- and postoperative measurements were analysed by repeated measures analysis of variance. Compared with preoperative data, postoperative data on UCVA revealed significant improvements in all patients (P<0.05). However, there was no significant difference in IOP. After the operation, CRT and GCT exhibited significant changes (P<0.05). Among these measures, CRT was significantly higher at one and three months postoperative (all P<0.01). GCT was significantly higher at 1wk, 1, and 3mo postoperative (all P<0.01). Changes in VD and SD were nonsignificant in both the SCP and DCP. There was no difference in postoperative changes between the ICL and Toric ICL groups. ICL and Toric ICL implantation both have good efficacy and safety for myopic eyes, but macular area changes that occur after surgery need attention.

Did parity affect bone mineral density of women in past populations? Parturition scars and BMD of Neolithic to modern skeletons from north-central Poland

Alterations in the region of the pubic symphysis and of the sacroiliac joints referred to as pelvic scarring are investigated by forensic scientists as potential indicators of pregnancy and parturition. Although pelvic scarring is not exclusively related to obstetrical events, the analysis of the relationship between this trait and skeletal mineral density in archaeological samples can give us a new insight into women's lives. The present study analyzes the relationship between the presence and the degree of pelvic scarring observed on the pelvic bones and bone mineral density (BMD) measured in the proximal femur in 190 skeletons of adult females representing archaeological populations from the region of Kujawy in north-central Poland and dating from 4500 BCE to the early 19th century CE. Multiple regression analysis has shown that 48% of the variability of bone mineral density of the female skeletons is explained by the time periods of the archaeological population, the individual's age at death, the depth of the proximal femur and the pelvic scarring. In all the analyzed skeletal samples, the females with a high degree of pelvic scarring regardless of age at death were characterized by higher bone mineral density than the females without such alterations. A high degree of scarring explains over 3% of the variability of BMD in the analyzed female skeletons. It seems that pelvic scarring together with bone mineral density can shed some light on reproductive phenomena in past populations.

Morphology and Conductive Properties of Carbon Black- and Graphite- Filled Conductive E poxy Micro-porous

Conductive composite requires a well dispersion of conductive filler, which is this difficult to be achieved low content of filler for high density conductive filler. This work investigates the effect of carbon black and graphite on the morphology and conductive properties of conductive epoxy micro-porous. The conductive epoxy micro-porous was prepared by using single emulsion technique. It involved the drop of epoxy-hardener-blowing agent-conductive filler mixture into corn oil at 160 °C and followed by the leaching process to remove excess corn oil. Results show the addition of conductive filler in epoxy matrix lead to increases porous structure in epoxy micro-porous. Carbon black filled epoxy micro-porous possessed smaller particles compared to graphite filled epoxy micro-porous. For skeleton density and total pore, both of the value increase with filler loading due to packing sphere effect. However, the skeleton density for carbon black filled epoxy micro-porous is higher compared to graphite filled epoxy micro-porous. For electrical conductivity, graphite filled micro-porous was higher than that of carbon black filled epoxy micro-porous.

Impaired layer specific retinal vascular reactivity among diabetic subjects.

PurposeTo investigate layer specific retinal vascular reactivity (RVR) in capillaries of diabetic subjects without DR or with only mild non-proliferative diabetic retinopathy (NPDR).MethodsA previously described nonrebreathing apparatus was used to deliver room air, 5% CO2, or 100% O2 to 41 controls and 22 diabetic subjects (with mild or no NPDR) while simultaneously acquiring fovea-centered 3x3mm2 Swept-Source Optical Coherence Tomography Angiography (SS-OCTA) images. Vessel skeleton density (VSD) and vessel diameter index (VDI) were calculated for each gas condition for the superficial retinal layer (SRL) and deep retinal layer (DRL). The superficial layer analysis excluded arterioles and venules. Data analysis was performed using mixed factorial analysis of covariance stratified by diabetic status. All models were adjusted for age, gender, and hypertension, and statistical significance for multiple comparisons from posthoc comparisons were defined at p<0.017.ResultsAmong controls, there was a significant difference in capillary VSD between all gas conditions (p<0.001). This difference was present in both the SRL and DRL. Among diabetics, there was no significant difference in response to CO2 conditions in the SRL (p = 0.072), and a blunted response to both CO2 (p = 0.9) and O2 in the DRL (p = 0.019). A significant gas effect was detected in the capillary VDI in the SRL of controls (p = 0.001), which was driven by higher VDI in the oxygen condition compared to that of carbon dioxide.ConclusionsImpairment in RVR in diabetic subjects is characterized by a paradoxical response to CO2 in both the SRL and DRL as well as an attenuated response to O2 in the DRL. These layer and gas specific impairments in diabetics seem to occur early in the disease and to be driven primarily at the capillary level.

Quantifying Subclinical and Longitudinal Microvascular Changes Following Episcleral Plaque Brachytherapy Using Spectral Domain-Optical Coherence Tomography Angiography.

To assess longitudinal microvascular changes in eyes treated with I-125 episcleral plaque brachytherapy (EPB). High resolution OCT angiograms of the central 3×3mm macula were obtained from I-125 episcleral plaque brachytherapy treated and untreated fellow eyes of 61 patients. Capillary density (vessel skeleton density, VSD) and caliber (vessel diameter index, VDI) were quantified using previously validated semi-automated algorithms. Nonperfusion was also quantified as flow impairment regions (FIR). Exams from treated and fellow eyes obtained pre-treatment and at 6-month, 1-year, and 2-year intervals were compared using generalized estimating equation linear models. Dosimetry maps were used to evaluate spatial correlation between radiation dose and microvascular metrics. At 6 months, treated eyes had significantly lower VSD (0.145 ± 0.003 vs 0.155 ± 0.002; p = 0.009) and higher FIR (2.01 ± 0.199 vs 1.46 ± 0.104; p = 0.010) compared to fellow eyes. There was a significant decrease in VSD and a corresponding increase in FIR even for treated eyes without clinically identifiable retinopathy at 6 months. VDI was significantly higher in treated eyes than in fellow eyes at 2 years (2.92 ± 0.025 vs 2.84 ± 0.018; p < 0.001). When our cohort was categorized into low dose radiation (<15Gy) and high dose radiation (>45Gy) to the fovea, there were significant differences in VSD and FIR between groups. OCTA can be used to quantify and monitor EPB induced retinopathy, and can detect vascular abnormalities even in the absence of clinically observable retinopathy. OCTA may therefore be useful in investigating treatment interventions that aim to delay EPB-induced radiation retinopathy.

OCT-Angiography Comparison between Obstructive Sleep Apnea Children and Normal Subjects in China

ABSTRACT Purpose Using optical coherence tomography angiography (OCT-A) to compare the retinal micro vessel alteration between obstructive sleep apnea (OSA) children and normal subjects. Methods One hundred-thirty-two eyes (132 participants) were recruited in this study. The average age of OSA group (66 eyes) and healthy control group (66 eyes) were 6.23 ± 1.73 and 6.76 ± 1.89 years, respectively. The retinal vascular network density indices and the fovea avascular zone (FAZ) size were analyzed by OCT-A. Results All of the OCT-A parafoveal vessel indices, including the vascular diameter (VD), vascular area density (VAD), vascular skeleton density (VSD), and vessel perimeter index (VPI) in the macular superficial/deep capillary plexus (SCP/DCP) as well as the FAZ in the DCP, were significantly lower in the OSA group than in the control group (p < .05). The four parafoveal quadrants indices (temporal, superior, nasal, and inferior) of VD and VAD in both the two layer were significantly lower in the OSA group than in control group (p < .05). However, the differences of VSD and VPI indices in the SCP/DCP did not show statistical significant changes. Conclusion The intermittent hypoxia in children with OSA might influence the retinal capillary vascular supply. We speculate that the indices of the quadrants are lower in OSA children compared with those in healthy controls, which may be due to the change of the retinal metabolic demands. OCT-A is an ideal method to evaluate the retinal alterations in pediatric OSA. Abbreviations OCT-A: optical coherence tomography angiography; OSA: obstructive sleep apnea; FAZ: fovea avascular zone; VD: vascular diameter; VAD: vascular area density; VSD: vascular skeleton density; VPI: vessel perimeter index; SCP/DCP: superficial/deep capillary plexus; BCVA: best corrected visual acuity; SE: spherical equivalent; AL: ocular axial length; T: temporal; N: nasal; (S): superior; (I): inferior; (SD): standard deviation

CHARACTERIZATION BY FRACTAL DIMENSION ANALYSIS OF THE RETINAL CAPILLARY NETWORK IN PARKINSON DISEASE.

To characterize retinal capillary complexity by optical coherence tomography angiography in Parkinson disease. Twenty-five Parkinson disease patients and 25 age- and gender-matched healthy controls were recruited. Optical coherence tomography angiography and optical coherence tomography imaged the superficial and deep retinal capillary plexuses and retinal structure. Retinal capillary skeleton density, retinal capillary perfusion density, and fractal dimension analysis of retinal capillary complexity were performed in the total annular zone and quadrant sectors. The thickness of retinal nerve fiber layer, ganglion cell layer and inner plexiform layer, and total retinal thickness were extracted from retinal structural images. Relationships among the retinal capillaries, retinal structure, and clinical parameters were analyzed. The superficial retinal capillary plexus in Parkinson disease patients had lower retinal capillary skeleton and perfusion densities and capillary complexity in the total annular zone and all quadrant sectors compared with healthy control subjects. The deep retinal capillary plexus retinal capillary complexity was decreased in the total annular zone and the superior and inferior quadrants. The retinal capillary complexity in the inferior quadrant was negatively correlated with the best-corrected visual acuity and disease duration (r = -0.61, r = -0.43, respectively, both P < 0.05). As determined by fractal analysis, retinal capillary complexity can be an objective biomarker in Parkinson disease.

Retinal and Choroidal Capillary Perfusion Are Reduced in Hypertensive Crisis Irrespective of Retinopathy.

PurposeHypertensive crisis causes end-organ damage through small-vessel damage as described histologically. Noninvasive optical coherence tomography angiography (OCTA) makes it possible to image retinal and choroidal capillaries on a microscopic level in vivo. We quantified eye vessel perfusion changes in hypertensive crisis using OCTA.MethodsPatients with hypertensive crisis (systolic blood pressure ≥180 mm Hg and/or diastolic blood pressure ≥110 mm Hg) and age-matched healthy controls were included in the study. OCTA en face 3 × 3-mm images of the superficial and deep retinal layers and the choriocapillaris were acquired. Outcome parameters included vessel density (VD) and vessel skeleton density (VSD) of the superficial and deep retinal layers, as well as flow voids of the choriocapillaris.ResultsTwenty-eight eyes of 17 patients and 31 age-matched control eyes of 18 healthy subjects were included. VD and VSD of the deep retinal layer were significantly reduced in hypertensive crisis (P ≤ 0.004). Choriocapillaris signal intensity was more heterogeneous in patients, and flow voids exhibited confluence with a larger average area and a lower absolute count (P ≤ 0.045). These changes were independent of time since onset of hypertensive crisis and of the presence and extent of retinopathy. Deep retinal changes were associated with renal end-organ failure (P = 0.045).ConclusionsHypertensive crisis is associated with a significant reduction in retinal and choroidal capillary perfusion based on OCTA findings. These alterations are independent of retinopathy and related to end-organ damage.Translational RelevanceOCTA might help distinguish hypertensive urgency from hypertensive emergency earlier than currently possible.

Ontogeny and potential function of poacher armor (Actinopterygii: Agonidae).

Many vertebrates are armored over all or part of their body. The armor may serve several functional roles including defense, offense, visual display, and signal of experience/capability. Different roles imply different tradeoffs; for example, defensive armor usually trades resistance to attack for maneuverability. The poachers (Agonidae), 47 species of scorpaeniform fishes, are a useful system for understanding the evolution and function of armor due to their variety and extent of armoring. Using publically available CT-scan data from 27 species in 16 of 21 genera of poachers we compared the armor to axial skeletal in the mid body region. The ratio of average armor density to average skeleton density ranged from 0.77 to 1.17. From a defensive point of view, the total investment in mineralization (volume * average density) is more interesting. There was 10 times the material invested in the armor as in the endoskeleton in some small, smooth plated species, like Aspidophoroides olrikii. At the low end, some visually arresting species like Percis japonica, had ratios as low as 2:1. We categorized the extent and type (impact vs. abrasion) in 34 Agonopsis vulsa across all 35+ plates in the eight rows along the body. The ventral rows show abrasive damage along the entire length of the fish that gets worse with age. Impact damage to head and tail plates gets more severe and occurs at higher rates with age. The observed damage rates and the large investment in mineralization of the armor suggest that it is not just for show, but is a functional defensive structure. We cannot say what the armor is defense against, but the abrasive damage on the ventrum implies their benthic lifestyle involves rubbing on the substrate. The impact damage could result from predatory attacks or from intraspecific combat.

Retinal microvascular metrics in untreated essential hypertensives using optical coherence tomography angiography.

To quantify early changes of macular microvascular density, complexity, and peripapillary vessel caliber in hypertension using optical coherence tomography angiography (OCTA). Hypertension (137 eyes) and healthy eyes (79 eyes) as control were involved in this prospective observational study. Indices of the microcirculation included vessel density (VD), skeleton density (SD), vessel diameter index (VDI), fractal dimension (FD) and foveal avascular zone (FAZ) of superficial retinal layer (SRL) and deep retinal layer (DRL), and peripapillary vessel calibers. The correlation of these indices with mean arterial pressure (MAP) and ocular perfusion pressure (OPP) was analyzed. Mean VD of DRL, SD of SRL and DRL, and FD of SRL and DRL were significantly reduced in the macula of hypertensive eyes (all P < 0.01). Meanwhile, hypertensive eyes had margin results of narrower peripapillary arteriolar caliber (P = 0.04). No significant finding was demonstrated on VD of SRL, VDI and FAZ of SRL and DRL, peripapillary total vascular caliber, and peripapillary venal caliber (all P > 0.05). SD and VD of the DRL correlated negatively with MAP (both R = - 0.152, P = 0.03). OCTA algorithms may provide an additional inexpensive tool to aid in the preclinical assessment of hypertensive subject.

Discordant vascular parameter measurements in diabetic and non-diabetic eyes detected by different optical coherence tomography angiography devices.

PurposeTo compare quantitative changes in macular parameters in diabetic patients detected by two optical coherence tomography angiography (OCTA) instruments.Methods80 phakic eyes were classified as no diabetes, diabetes without diabetic retinopathy (DR), mild non-proliferative diabetic retinopathy (NPDR), and severe NPDR or proliferative DR (PDR). OCTA was performed using devices from two manufacturers (Zeiss and Heidelberg). Superficial and deeper vascular skeleton density (SVSD, DVSD), superficial and deeper vessel area density (SVAD, DVAD), choriocapillaris flow voids (CCFV), and choroidal flow voids (CFV) were calculated. Inter-device comparisons were performed using the size comparison index (SCI) and the discrepancy index (DI).ResultsThe two devices were inconsistent in SVSD, DVSD, DVAD, CCFV and CFV parameters (all P < 0.05). In addition, the SCI was positive for DVAD (all P < 0.001) and negative for SVSD, DVSD, CCFV and CFV in all groups (all P <0.001), except for DVSD in severe NPDR or PDR. The discrepancy index was not significantly different among groups for SVD, SPD, DVD, DPD and CFV (all P> 0.05). The mean DI of CCFV was statistically different between the four groups (P < 0.001).ConclusionsThe two instruments were largely inconsistent in the measurement of macular parameters relevant to DR. The choice of imaging device can impact OCTA analytics and should be taken into account when drawing conclusions about DR-related changes.

Effect of diets and light regimes on calcification and somatic growth of the sea urchin Tripneustes gratilla elatensis

The effects of Ulva lactuca (cultivated in the outlet of an Integrated Multi-Trophic Aquaculture [IMTA] system) vs. formulated diets on the somatic growth of the sea urchin Tripneustes gratilla elatensis were evaluated under three light regimes (continuous light, continuous darkness and ambient dark-light cycle). Total CaCO3 precipitation and calcification rate, test diameter and surface area were used as growth parameters. The different light regimes tested did not appear to have a significant effect on any of these parameters. Sea urchins exposed to ambient light had significantly faster growth (measured as wet weight) than those exposed to continuous darkness or continuous light, a phenomenon attributed to gonad growth at the expense of shell growth. IMTA-produced U. lactuca was the preferential food source for promoting calcification, as average calcification rates in sea urchins fed formulated and U. lactuca diets, (1.31 ± 0.69 and 2.1 ± 0.31 mg h−1SU−1, respectively), were significantly higher in the urchins fed U. lactuca. Calcification rates in adult T. gratilla elatensis, measured as percentage of skeleton added per day, decreased with the juveniles' increase in size, as larger sea urchins allocated most of the CaCO3 in favour of skeleton density rather than somatic growth. A 3D laser scanner was used to measure test surface area, from which significant correlation could be extrapolated extremely accurately between test diameter and the sea urchin surface area, volume, and skeletal and test dry weight, while alkalinity depletion in the surrounding sea water was used to calculate total calcium carbonate precipitation and calcification rates in the sea urchin. Both measurements applied for the first time to sea urchins, can be used to monitor the progress of growth in an industrial echinoculture setting.

Clinical Utility of Triplicate En Face Image Averaging for Optical Coherence Tomography Angiography in Glaucoma and Glaucoma Suspects.

The purpose of this study was to test the hypothesis that triplicate averaging of the RPC layer improves visualization and diagnostic accuracy of OCTA for glaucoma. This is a cross-sectional study involving 63 primary open-angle glaucoma patients and 70 age-matched glaucoma suspects. Triplicate 6×6 mm OCTA scans of the optic nerve head were acquired, and the RPC layer was extracted. RPC en face images were registered and averaged. Parameters of global entropy, global standard deviation, local texture correlation, local homogeneity, signal-to-noise ratio, and intercapillary distance were used to measure the change in visualization with averaging. Vessel area density (VAD), vessel skeleton density (VSD), and flux parameters were calculated in a 2.8 mm annulus excluding the optic disc. The diagnostic accuracy of these parameters for glaucoma was assessed by calculating the area under the receiver operating curve (AUC) values. Three-frame averaging resulted in decreased global entropy and global standard deviation (Ps<0.001), and increased local texture correlation, local homogeneity, signal-to-noise ratio, and intercapillary distance (Ps<0.001). Averaged images also had reduced VAD, VSD, and flux (Ps<0.001). AUC was significantly increased for VSD after image averaging (P=0.018), while no significant change in AUC was observed for VAD (P=0.229) or flux (P=0.193). Triplicate averaging improves visualization of the RPC layer and the diagnostic accuracy of VSD for glaucoma. The impact of image averaging on OCTA diagnostic performance and other potential applications warrants further exploration.

Repeatability and reproducibility of vessel density measurements on optical coherence tomography angiography in diabetic retinopathy

Understanding the precision of measurements on and across optical coherence tomography angiography (OCTA) devices is critical for tracking meaningful change in disease. The purpose of this study is to investigate the repeatability and reproducibility of vessel area density and vessel skeleton density measurements from various commercial OCTA devices in diabetic eyes. Patients were imaged three consecutive times each on three different OCTA devices. En face OCTA images of the superficial capillary plexus, deep capillary plexus, and full retinal layer were exported for analysis. Vessel area density and vessel skeleton density were calculated. The coefficient of repeatability (CoR) was calculated to assess the repeatability of these measurements, and linear mixed models were utilized to assess the reproducibility of these measurements. Forty-four eyes from 27 diabetic patients were imaged. Normalized CoR values ranged between 3.44 and 6.65% when calculated for vessel area density and between 1.35 and 23.39% when calculated for vessel skeleton density. When stratified by disease severity, the swept-source OCTA device consistently produced the smallest CoR values for vessel area density in the full retinal layer. Vessel area density measurements were repeatable across the two spectral-domain devices in the full retinal layer when all severities were combined, as well as in diabetic patients without retinopathy, mild nonproliferative diabetic retinopathy (NPDR), and moderate NPDR. Vessel area density measured in the full retinal layer may be a more precise measure than vessel skeleton density to follow diabetic retinopathy patients both on the same device and across devices.