Relative Contributions of Intracranial Pressure and Intraocular Pressure on Lamina Cribrosa Behavior

Purpose. To characterize the relative contributions of intraocular pressure (IOP) and intracranial pressure (ICP) on lamina cribrosa (LC) behavior, specifically LC depth (LCD) and LC peak strain. Methods. An axially symmetric finite element model of the posterior eye was constructed with an elongated optic nerve and retro-orbital subarachnoid space ensheathed by pia and dura mater. -e mechanical environment in LC was evaluated with ICP ranging from 5 to 15mmHg and IOP from 10 to 45 mmHg. LCD and LC peak strains at various ICP and IOP levels were estimated using full factorial experiments. Multiple linear regression analyses were then applied to estimate LCD and LC peak strain using ICP and IOP as independent variables. Results. Both increased ICP and decreased IOP led to a smaller LCD and LC peak strain. -e regression correlation coefficient for LCD was −1.047 for ICP and 1.049 for IOP, and the ratio of the two regression coefficients was −1.0. -e regression correlation coefficient for LC peak strain was −0.025 for ICP and 0.106 for IOP, and the ratio of the two regression coefficients was −0.24. A stiffer sclera increased LCD but decreased LC peak strain; besides, it increased the relative contribution of ICP on the LCD but decreased that on the LC peak strain. Conclusions. ICP and IOP have opposing effects on LCD and LC peak strain. While their effects on LCD are equivalent, the effect of IOP on LC peak strain is 3 times larger than that of ICP. -e influences of these pressure are dependent on sclera material properties, which might explain the pathogenesis of ocular hypertension and normal-tension glaucoma

Relative Contributions of Intracranial Pressure and Intraocular Pressure on Lamina Cribrosa Behavior

Purpose. To characterize the relative contributions of intraocular pressure (IOP) and intracranial pressure (ICP) on lamina cribrosa (LC) behavior, specifically LC depth (LCD) and LC peak strain. Methods. An axially symmetric finite element model of the posterior eye was constructed with an elongated optic nerve and retro-orbital subarachnoid space ensheathed by pia and dura mater. -e mechanical environment in LC was evaluated with ICP ranging from 5 to 15mmHg and IOP from 10 to 45 mmHg. LCD and LC peak strains at various ICP and IOP levels were estimated using full factorial experiments. Multiple linear regression analyses were then applied to estimate LCD and LC peak strain using ICP and IOP as independent variables. Results. Both increased ICP and decreased IOP led to a smaller LCD and LC peak strain. -e regression correlation coefficient for LCD was −1.047 for ICP and 1.049 for IOP, and the ratio of the two regression coefficients was −1.0. -e regression correlation coefficient for LC peak strain was −0.025 for ICP and 0.106 for IOP, and the ratio of the two regression coefficients was −0.24. A stiffer sclera increased LCD but decreased LC peak strain; besides, it increased the relative contribution of ICP on the LCD but decreased that on the LC peak strain. Conclusions. ICP and IOP have opposing effects on LCD and LC peak strain. While their effects on LCD are equivalent, the effect of IOP on LC peak strain is 3 times larger than that of ICP. -e influences of these pressure are dependent on sclera material properties, which might explain the pathogenesis of ocular hypertension and normal-tension glaucoma

Three-dimensional shape analysis of peripapillary retinal pigment epithelium-basement membrane layer based on OCT radial images

The peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer angle was recently proposed as a potential index for estimating intracranial pressure noninvasively. However, the ppRPE/BM layer angle, measured from the optical coherence tomography (OCT) scans, varied across the radial directions of the optic disc. This made the ppRPE/BM layer angle difficult to be utilized in its full potential. In this study, we developed a mathematical model to quantify the ppRPE/BM layer angles across radial scans in relation to the ppRPE/BM 3D morphology in terms of its 3D angle and scanning tilt angles. Results showed that the variations of the ppRPE/BM layer angle across radial scans were well explained by its 3D angle and scanning tilt angles. The ppRPE/BM layer 3D angle was reversely fitted from the measured ppRPE/BM layer angles across radial directions with application to six eyes from four patients, who underwent medically necessary lumbar puncture. The fitted curve from our mathematical model matched well with the experimental measurements (R2 \u3e 0.9 in most cases). This further validated our mathematical model. The proposed model in this study has elucidated the variations of ppRPE/BM layer angle across 2D radial scans from the perspective of the ppRPE/BM layer 3D morphology. It is expected that the ppRPE/BM layer 3D angle developed in this study could be further exploited as a new biomarker for the optic disc

MECHANICAL PERFORMANCE OF PLLA STENT

Stent implantation is widely used to treat blocked lumen. Stents were meshed structure made of polymers and metal alloys, including stainless steel, cobalt chrome and nitinol [1]. Clinical studies had demonstrated that stents helped to scaffold the diseased lesion up to one year when tissue adapted to the stented environment [2]. However, the permanently implanted stents inside artery were associated with complications such as stent fracture, tissue inflammation, in-stent restenosis and thrombosis [3]. Currently, biodegradable stents are attracting more attention due to its potential long-term efficacy in treating blocked lumens. The detailed characterizations of biodegradable stents are essential for the desired clinical outcomes. In this work, the mechanical performance of Absorb GTI™ Bioresorbable stent made of PLLA (Poly-L-Lactide Acid) was studied using finite element method (FEM). Both the stent crimping and deployment were quantified towards the optimization of its scaffolding capacity in a limited time

INFLUENCE OF INTRACRANIAL PRESSURE ON THE LAMINA CRIBROSA

ABSTRACT Glaucoma is an eye disease related with vision field loss. Although previous study has investigated the influence of intraocular pressure (IOP) on the glaucoma damage to the lamina cribrosa (LC), the intracranial pressure's (ICP) effect on the LC has never been elucidated. The goal of this work is to determine the effect of ICP on the LC

Mirror: A Universal Framework for Various Information Extraction Tasks

Sharing knowledge between information extraction tasks has always been a challenge due to the diverse data formats and task variations. Meanwhile, this divergence leads to information waste and increases difficulties in building complex applications in real scenarios. Recent studies often formulate IE tasks as a triplet extraction problem. However, such a paradigm does not support multi-span and n-ary extraction, leading to weak versatility. To this end, we reorganize IE problems into unified multi-slot tuples and propose a universal framework for various IE tasks, namely Mirror. Specifically, we recast existing IE tasks as a multi-span cyclic graph extraction problem and devise a non-autoregressive graph decoding algorithm to extract all spans in a single step. It is worth noting that this graph structure is incredibly versatile, and it supports not only complex IE tasks, but also machine reading comprehension and classification tasks. We manually construct a corpus containing 57 datasets for model pretraining, and conduct experiments on 30 datasets across 8 downstream tasks. The experimental results demonstrate that our model has decent compatibility and outperforms or reaches competitive performance with SOTA systems under few-shot and zero-shot settings. The code, model weights, and pretraining corpus are available at https://github.com/Spico197/Mirror .Comment: Accepted to EMNLP23 main conferenc

Effects of body size and load carriage on lower-extremity biomechanical responses in healthy women

Abstract Background Musculoskeletal injuries, such as stress fractures, are the single most important medical impediment to military readiness in the U.S. Army. While multiple studies have established race- and sex-based risks associated with a stress fracture, the role of certain physical characteristics, such as body size, on stress-fracture risk is less conclusive. Methods In this study, we investigated the effects of body size and load carriage on lower-extremity joint mechanics, tibial strain, and tibial stress-fracture risk in women. Using individualized musculoskeletal-finite-element-models of 21 women of short, medium, and tall statures (n = 7 in each group), we computed the joint mechanics and tibial strains while running on a treadmill at 3.0 m/s without and with a load of 11.3 or 22.7 kg. We also estimated the stress-fracture risk using a probabilistic model of bone damage, repair, and adaptation. Results Under all load conditions, the peak plantarflexion moment for tall women was higher than those in short women (p < 0.05). However, regardless of the load condition, we did not observe differences in the strains and the stress-fracture risk between the stature groups. When compared to the no-load condition, a 22.7-kg load increased the peak hip extension and flexion moments for all stature groups (p < 0.05). However, when compared to the no-load condition, the 22.7-kg load increased the strains and the stress-fracture risk in short and medium women (p < 0.05), but not in tall women. Conclusion These results show that women of different statures adjust their gait mechanisms differently when running with external load. This study can educate the development of new strategies to help reduce the risk of musculoskeletal injuries in women while running with external load

Effect of stride length on the running biomechanics of healthy women of different statures

Abstract Background Tibial stress fracture is a debilitating musculoskeletal injury that diminishes the physical performance of individuals who engage in high-volume running, including Service members during basic combat training (BCT) and recreational athletes. While several studies have shown that reducing stride length decreases musculoskeletal loads and the potential risk of tibial injury, we do not know whether stride-length reduction affects individuals of varying stature differently. Methods We investigated the effects of reducing the running stride length on the biomechanics of the lower extremity of young, healthy women of different statures. Using individualized musculoskeletal and finite-element models of women of short (N = 6), medium (N = 7), and tall (N = 7) statures, we computed the joint kinematics and kinetics at the lower extremity and tibial strain for each participant as they ran on a treadmill at 3.0 m/s with their preferred stride length and with a stride length reduced by 10%. Using a probabilistic model, we estimated the stress-fracture risk for running regimens representative of U.S. Army Soldiers during BCT and recreational athletes training for a marathon. Results When study participants reduced their stride length by 10%, the joint kinetics, kinematics, tibial strain, and stress-fracture risk were not significantly different among the three stature groups. Compared to the preferred stride length, a 10% reduction in stride length significantly decreased peak hip (p = 0.002) and knee (p < 0.001) flexion angles during the stance phase. In addition, it significantly decreased the peak hip adduction (p = 0.013), hip internal rotation (p = 0.004), knee extension (p = 0.012), and ankle plantar flexion (p = 0.026) moments, as well as the hip, knee, and ankle joint reaction forces (p < 0.001) and tibial strain (p < 0.001). Finally, for the simulated regimens, reducing the stride length decreased the relative risk of stress fracture by as much as 96%. Conclusions Our results show that reducing stride length by 10% decreases musculoskeletal loads, tibial strain, and stress-fracture risk, regardless of stature. We also observed large between-subject variability, which supports the development of individualized training strategies to decrease the incidence of stress fracture

Three-Dimensional Characterization of Peripapillary Retinal Pigment Epithelium-Basement Membrane Layer in Patients following Lumbar Puncture

Purpose: To develop and test an innovative semi-automatic method for quantifying the three-dimensional morphology of the peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer, with application to lumbar puncture (LP) patients. Methods: Nineteen patients undergoing LP were recruited. The optic nerve head images of both eyes were acquired in 12 radial directions using optical coherence tomography (OCT) before and after LP. For each OCT image, the ppRPE/BM layer was automatically segmented with manual corrections by independent graders when necessary. The linear regression model of the ppRPE/BM layer was fitted using the least squares approach, and the ppRPE/BM layer angle was measured as the slope of the linear regression line. The Bland–Altman plots and intraclass correlations (ICC) were used to assess the inter-observer reliabilities in measuring the ppRPE/BM layer angle. The repeated measures ANOVA analysis was applied to determine whether the ppRPE/BM layer angle changes following LP varied across the radial directions. Results: The percentages of scans that required manual corrections were 24% and 32% in the right eyes and left eyes, respectively. The Bland–Altman plots and ICC demonstrated excellent inter-observer reliability. The ppRPE/BM layer angle varied significantly across the 12 radial OCT scanning directions both before and after LP. However, the LP-induced changes in the ppRPE/BM layer angle across different radial directions were not statistically significant (p-value \u3e 0.01). Conclusions: The three-dimensional quantifications of the ppRPE/BM layer angles, enabled by the semi-automatic method, provided enhanced information of the optic nerve head structure. For LP patients, the ppRPE/BM layer angle changes following the LP did not vary significantly across various radial directions, indicating that it could be evaluated in any radial direction

Numerical Simulation and in vivo Study of Optic Nerve Head Towards Non-invasive Monitoring of Intracranial Pressure

Intracranial pressure (ICP) is an important biomarker for health assessment. It is highly desirable to identify a non-invasive method for ICP monitoring in clinical practice. The anatomy of the optic nerve head (ONH) visualized using the optical coherence tomography (OCT) was recently recognized to be correlated with the ICP alternation, which might serve as a non-invasive marker for the ICP estimation. This thesis is to investigate the role of ICP on the development of optic neuropathy through numerical simulation, and further investigate a potential biomarker in the ONH for the non-invasive ICP estimation. The result from this study would facilitate the prevention and early diagnosis of ICP related ocular disease, and further, provide a method for non-invasive monitoring of ICP. A three-dimensional human eye model with a detailed characterization of the orbital components was developed to simulate the indirect traumatic optic neuropathy induced by the primary blast (shock wave). It was found there was a transient elevation of ICP and excessively high strain rate throughout the optic nerve; this was related to the axon damage and vision loss. The relative contributions between the ICP and intraocular pressure (IOP) on the peak strain and depth of the lamina cribrosa (LC) were also investigated due to their relationship to glaucoma. It was then found ICP played an equivalent role in the LC depth as that of IOP. However, IOP was still the dominant factor in deciding the peak strain in the LC. The peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer angle in the ONH was identified as the potential marker for the ICP monitoring, which was quantified through a semi-automatic method developed in this work. The robustness and reliability of the method were validated against the clinical data of patients who underwent the lumbar puncture (LP). The multivariate analysis revealed the ppRPE/BM layer angle changes were found best correlated with the translaminar pressure difference changes. Furthermore, a mathematical model was developed to interpret the ppRPE/BM layer angle variations across the radial directions. Based on the developed model, we could extract the structural ppRPE/BM layer angle through a reverse fitting. These results indicate the structural ppRPE/BM layer angle may be used as a biomarker for the disease assessment as well as the non-invasive ICP estimation