In-vivo characterization of scleral rigidity in myopic eyes using fundus-pulsation optical coherence elastography
May 1, 2024 | Ophthalmology | California Institute of Technology, University of WashingtonAndrew Chen, Daniel M. Schwartz, Jonathan Li, Karine D. Bojikian, Kasra A. Rezaei, Lisa C. Olmos, Philip P. Chen, Raghu C. Mudumbai, Ruikang K. Wang, Zhaoyu Gong
The sclera plays an important role in the structural integrity of the eye. However, as myopia progresses, the elongation of the eyeball exerts stretching forces on the posterior sclera, which typically happens in conjunction with scleral remodeling that causes rigidity loss. These biomechanical alterations can cause localized eyeball deformation and vision impairment. Therefore, monitoring scleral rigidity is clinically important for the management and risk assessment of myopia. In this study, we propose fundus pulsation optical coherence elastography (FP-OCE) to characterize posterior scleral rigidity in living humans. This methodology is based on a choroidal pulsation model, where the scleral rigidity is inversely associated with the choroidal max strain obtained through phase-sensitive optical coherence tomography (PhS-OCT) measurement of choroidal deformation and thickness. Using FP-OCE, we conducted a pilot clinical study to explore the relationship between choroidal strain and...
Direct Numerical Modeling as a Tool for Optical Coherence Tomography Development: SNR (Sensitivity) and Lateral Resolution Test Target Interpretation
May 1, 2024 | General Technology | University of LiverpoolSamuel Lawman, Yao-Chun Shen
Optical Coherence Tomography (OCT) is a growing family of biophotonic imaging techniques, but in the literature there is a lack of easy-to-use tools to universally directly evaluate a device’s theoretical performance for a given metric. Modern computing tools mean that direct numerical modeling can, from first principles, simulate the performance metrics of a specific device directly without relying on analytical approximations and/or complexities. Here, we present two different direct numerical models, along with the example MATLAB code for the reader to adapt to their own systems. The first model is of photo-electron shot noise at the detector, the primary noise source for OCT. We use this firstly to evaluate the amount of additional noise present (1.5 dB) for an experimental setup. Secondly, we demonstrate how to use it to precisely quantify the expected shot noise SNR limit difference between time-domain and Fourier-domain OCT systems in a given hypothetical experiment. The se...
A systematic review of clinical applications and diagnostic efficacy of intravascular optical coherence tomography in cardiology
May 1, 2024 | Cardiology | Universidad Católica Santiago de GuayaquilSantiago Israel Cárdenas Herrera, Jorge Andres Rivera Barzallo, Juan José Martínez Saltos, Víctor Manuel Polo Roldán, Angelica Marina Basantes Castillo, Edith Viviana Muñoz Cunduri, Rafael Andres Mosquera-Ceprian, Washington Javier Masapanta Pilatasig, Ana Paula Coronel Mite, Vanessa Marisol Almeida Sacoto
Intravascular Optical Coherence Tomography (OCT) has emerged advanced imaging modality in cardiology, offering high-resolution visualization of coronary artery structures. Since its inception in the late 1990s, OCT has undergone significant advancements, transitioning from time-domain to frequency-domain systems, thereby enhancing its clinical viability and diagnostic efficacy. We aimed to comprehensively assess the clinical applications and diagnostic efficacy of intravascular OCT in cardiology, particularly in guiding percutaneous coronary interventions (PCI) and evaluating coronary artery diseases. In methodology, A systematic search was conducted in PubMed and Google Scholar databases for studies published between 2013 and 2023, comparing OCT with intravascular ultrasound (IVUS) and conventional angiography (C.A.) in guiding PCI procedures. Studies were selected based on predefined inclusion and exclusion criteria, focusing on major adverse cardiovascular events (MACE), cardia...
Combining Reflectance Confocal Microscopy, Optical Coherence Tomography, and Ex-Vivo Fluorescence Confocal Microscopy for Margin Assessment in Basal Cell Carcinoma Excision
May 1, 2024 | Dermatology | La Sapienza University of Rome, University of Modena and Reggio EmiliaAnna Maria Cesinaro, Barbara Ferrari, Camilla Chello, Carlo Cota, Carmen Cantisani, Caterina Longo, Elena Rossi, Federica Trovato, Giovanni Pellacani, Marco Ardigo, Marco Di Fraia, Shaniko Kaleci, Silvana Ciardo, Simone Michelini, Victor Desmond Mandel
Introduction: Recent developments of noninvasive, high-resolution imaging techniques, such as reflectance confocal microscopy (RCM) and optical coherence tomography (OCT), have enhanced skin cancer detection and precise tumor excision particularly in highly aggressive and poorly defined basal cell carcinomas (BCCs)
Objectives: The aim of this pilot study is to assess feasibility and reproducibility of a systematic clinical workflow combining noninvasive (RCM-OCT) and invasive fluorescence confocal microscopy (FCM) imaging modalities in pre- and intra-surgical evaluations of lateral and deep margins of BCC.
Methods: Superficial incisions were made 2 mm beyond the clinical-dermoscopic BCC margins. Lateral margins were then explored with OCT and RCM. In positive margins, a further cut was made 2 mm distal from the previous. A final RCM/OCT-based double-negative margin was drawn around the entire perimeter of the lesion before referring to surgery. The freshly excised specimen was t...
Changes in the retina and choroid in patients with internal carotid artery stenosis: a systematic review and meta-analysis
May 1, 2024 | Cardiology, Ophthalmology | China Academy of Chinese Medical SciencesChuanhong Jie, Jingying Wang, Weiqiong Zhang, Xiaoyu Hou, Xuqi Bi, Yu Deng, Yuanyuan Li, Ziqiang Liu
Background: Internal carotid artery stenosis (ICAS) is a prevalent vascular condition associated with ischemic cerebrovascular disease. The ophthalmic artery is the first branch of the internal carotid artery stenosis (ICA). Given the crucial role of the ICA in ocular perfusion, we aimed to assess the thickness and vessel density of the retina and choroid in individuals with ICAS.
Methods: The PubMed and Embase databases were searched from inception to 10 January 2023 for studies evaluating retinal and choroidal changes between ICAS patients and healthy controls using optical coherence tomography (OCT) or optical coherence tomography angiography (OCTA). Data of interest were extracted and analyzed using Stata software version 16.
Results: Thirteen studies involving 419 ICAS eyes and 398 healthy eyes were included. The pooled results demonstrated that the average thickness of peripapillary retinal nerve fiber layer (pRNFL) (WMD = -0.26, 95% CI: -0.45 to -0.08, P = 0.005), ganglio...
Evaluating the microcirculation of the dome-shaped macula and its complications in adults with highly myopic eyes by swept-source optical coherence tomography angiography
May 1, 2024 | Ophthalmology | Tianjin Medical UniversityChen Chen, Haoru Li, Jinyuan Sui, Nan Gao, Qing He, Ruihua Wei, Yang Bai, Zhiqing Li, Ziwen Sun
Purpose: The aim of this study was to investigate the microcirculatory characteristics of the dome-shaped macula (DSM), its complications in highly myopic eyes and to explore the factors associated with a DSM.
Methods: This cross-sectional case-control study included a total of 98 subjects (98 eyes): 49 eyes with DSM and 49 eyes without DSM. The axial length (AL) of the myopic eyes was matched 1:1 to eliminate the effect of AL differences on the results. Choroidal (CT) and scleral thickness (ST) and other structural parameters were assessed by swept-source optical coherence tomography (SS-OCT). OCT angiography was used to measure microcirculatory parameters in highly myopic eyes.
Results: Subjects with DSM had thinner subfoveal choroidal thickness (46.01 ± 13.25 vs. 81.62 ± 48.26 μm; p < 0.001), thicker subfoveal scleral thickness (SFST; 331.93 ± 79.87 vs. 238.74 ± 70.96 μm; p < 0.001) and thinner foveal CT (66.86 ± 24.65 vs. 107.85 ± 52.65 μm; p < 0.001) compared to su...
Effect of isoflurane anaesthetic time on ocular a-scan ultrasonography measures and their relationship to age and OCT measures in the guinea pig
May 1, 2024 | Ophthalmology | University of NewcastleSally Anne McFadden, William E. Myles, Yusupjan Abdulla
A-scan ultrasonography enables precise measurement of internal ocular structures. Historically, its use has underpinned fundamental studies of eye development and aberrant eye growth in animal models of myopia; however, the procedure typically requires anaesthesia. Since anaesthesia affects intra-ocular pressure (IOP), we investigated changes in internal ocular structures with isoflurane exposure and compared measurements with those taken in awake animals using optical coherence tomography (OCT). Continuous A-scan ultrasonography was undertaken in tri-coloured guinea pigs aged 21 (n = 5), 90 (n = 5) or 160 (n = 5) days while anaesthetised (up to 36 mins) with isoflurane (5% in 1.5L/min O2). Peaks were selected from ultrasound traces corresponding to the boundaries of the cornea, crystalline lens, retina, choroid and sclera. OCT scans (Zeiss Cirrus Photo 800) of the posterior eye layers were taken in 28-day-old animals (n = 19) and compared with ultrasound traces, with choroid and ...
Long-term Intravital Investigation of an Orthotopic Glioma Mouse Model via Optical Coherence Tomography Angiography
May 1, 2024 | Ophthalmology | Harbin Medical University, Xiamen UniversityGuangxing Wang, Huiling Wu, Jiwei Xing, Kaili Zheng, Kangwei Zhou, Lisong Lin, Qingliang Zhao, Qiong Yang, Shuting Ling, Xiaofei Wen, Yuying Zhou
Background/aim: Probing brain tumor microvasculature holds significant importance in both basic cancer research and medical practice for tracking tumor development and assessing treatment outcomes. However, few imaging methods commonly used in clinics can noninvasively monitor the brain microvascular network at high precision and without exogenous contrast agents in vivo. The present study aimed to investigate the characteristics of microvasculature during brain tumor development in an orthotopic glioma mouse model.
Materials and methods: An orthotopic glioma mouse model was established by surgical orthotopic implantation of U87-MG-luc cells into the mouse brain. Then, optical coherence tomography angiography (OCTA) was utilized to characterize the microvasculature progression within 14 days.
Results: The orthotopic glioma mouse model evaluated by bioluminescence imaging and MRI was successfully generated. As the tumor grew, the microvessels within the tumor area slowly decrease...
3D Mapping of the DMEK Detachment Area from OCT Scans of the Anterior Segment of the Eye – Clinical Applications
May 1, 2024 | Ophthalmology | University of FreiburgAndreas Glatz, Anne-Marie S. Kladny, Daniel Bernhard Zander, Daniel Böhringer, Judith-Lisa Lieberum, Katrin Wacker, Thomas Reinhard
Graft detachment is the most common complication after Descemet membrane endothelial keratoplasty (DMEK). To assess the amount of graft detachment, precision is limited when using slit-lamp biomicroscopy. Detachment of DMEK grafts can be assessed automatically on anterior segment optical coherence tomography (AS OCT) images and allows visualization of the area and volume of detachment using 3D maps. This article provides an overview of its applications such as accurately assessing the course of natural graft attachment, identification of potential risk factors for detachment and evaluation of the long-term effect of graft detachment. The 3D map of DMEK detachment may support researchers and clinicians in precise quantification of the area and volume of graft detachment even in large data sets, and the intuitive, fast and reliable evaluation.
Choroidal Thickness in healthy eyes measured by Widefield Optical Coherence Tomography
April 30, 2024 | Ophthalmology | Castilla de la Mancha UniversityBlanca Eslava, Jorge Ruiz-Medrano, Jose M. Ruiz-Moreno, Mariluz Puertas, Sofia Bryan
Introduction: The choroid and its role in posterior segment pathology has become an increasing subject of study. The objective of the present study was to analyze choroidal thickness (CT) in healthy eyes by widefield (WF) optical coherence tomography (OCT) up to the periphery and to compare the reliability of manual versus automatic measurement.
Methods: Cross-sectional and non-interventional study conducted on 191 healthy eyes of 101 patients. All patients were scanned by using WF-OCT (Xephilio WF-OCT S1; Canon Corp, Tokyo, Japan). CT was measured in 2000 µm intervals automatically using the built-in software and manually by two masked observers. All analyses were performed using the IBM-PSSS statistical software program (IBM-SPSS, v. 28.0.0.0, Chicago, IL, USA).
Results: CT was measured in 100% of the sample. The mean age of the study cohort was 39.05±19.06 years old. Mean subfoveal (SF)CT measured automatically was 343.67±84.18 μm and manually was 336.55±75.57 μm. The thickes...
Optical Coherence Tomography Angiography Findings Associated With Accelerated Hypertension
April 30, 2024 | Ophthalmology | Lilavati HospitalSalil Mehta
Introduction Accelerated hypertension, that is a systolic blood pressure greater than 180 mmHg and a diastolic blood pressure greater than 120 mmHg is often accompanied by fundoscopic signs with the potential of systemic and visual morbidity. We report on the clinical and optical coherence tomography angiography (OCTA) findings in a cohort of hypertensive patients with accelerated hypertension.
Methods Patients, presenting to the emergency room/intensive care unit, who met the clinical definition of accelerated hypertension (a blood pressure >180/120 mmHg,), were triaged to the intensive care unit. Following blood pressure reduction via pharmacological methods, a standard panel of hematological tests, cardiac evaluation tests, and the necessary systemic imaging was performed. They underwent a bedside dilated fundus examination with subsequent fundus photography/OCTA using a Topcon DRI OCT plus (Topcon Corporation, Tokyo, Japan). The records of these patients were eva...
Modernizing the evaluation of infantile nystagmus: the role of handheld optical coherence tomography
April 30, 2024 | Ophthalmology | Duke UniversityMays El-Dairi, Rizul Naithani, Samuel Alvarez, Sharon Freedman, Suzanna Joseph, Tanya Glaser
Background Infantile nystagmus syndrome can be associated with an afferent problem (anterior or posterior segment) or constitute an isolated idiopathic disorder. With a normal ophthalmic examination, current guidelines recommend electroretinography (ERG) rather than magnetic resonance (MRI) for preliminary workup. Given the limited use of optical coherence tomography (OCT) in preverbal children, the purpose of this study was to evaluate the role of handheld OCT (HH-OCT) in the initial diagnostic evaluation of infantile nystagmus. Methods In this cross-sectional case series, the medical records of all children with infantile nystagmus and HH-OCT imaging at the Duke Eye Center from August 2016 to July 2021 were retrospectively reviewed. Children with anterior segment disorders or obvious retina/optic nerve structural pathology, bilateral ophthalmoplegia, or Down syndrome were excluded. Two masked pediatric ophthalmologists graded HH-OCT images for optic nerve head and...
Duke Biomedical Engineering chairman and OCT pioneer Joseph Izatt passes away
April 30, 2024 | Other News | Duke UniversityJoseph A. Izatt
Joseph Izatt, the Michael J. Fitzpatrick Professor of Engineering and chair of Duke’s Department of Biomedical Engineering (BME), passed away on Sunday, April 7 at the age of 61.
As a researcher and inventor, Izatt was instrumental in the development of optical coherence tomography (OCT). The imaging technique uses optical interferometry scan through layers of soft tissue, including the retina and the back of the eye to obtain highly detailed images that guide diagnosis and treatment decisions by ophthalmologists.
Izatt had a lifelong passion for science that he inherited from his father and he started to work with lasers while still in high school. After graduating, he attended Massachusetts Institute of Technology, earning a bachelor’s degree in physics in 1986, followed by a doctorate in applied radiation physics in 1991. Following 2 years of postdoctoral training, he was a professor of Biomedical Engineering at Case Western University in Cleveland, Ohio, before moving to Duk...
Deep learning model for AI: Stopping nascent GA in its tracks
April 30, 2024 | OphthalmologyLynda Charters
A recent study conducted by US and Australian researchers found that a deep learning model for an artificial intelligence (AI)–assisted approach for detecting nascent geographic atrophy (GA) has the future potential to both have “near-perfect” detection abilities and ease the diagnostic burden carried by practices,1 according to co–first authors Heming Yao, PhD, from Genentech, Inc, San Francisco, California, and Zhichao Wu, PhD, BAppSc(Optom), from the Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia.
Having the ability to detect GA before it has a chance to take hold was among the goals of this study. The authors wanted to develop a model to screen images for specific features indicative of nascent GA on optical coherence tomography (OCT) scans.
On OCT images, the specific features of photoreceptor loss referred to as nascent GA2-5 have shown promise as one such biomarker for providing a strong predictor of GA onset.5,6 The fea...
Changes in environmental conditions can be evaluated by detecting the conditions in indicator plants. Indicator plants are sensitive to specific environmental stresses. This research focused on white clover as an indicator plant for ozone. To analyze the effects of weaker stresses, compact OCT (Optical coherence tomography) for plants was developed, which allows for non-invasive and non-contact cross-sectional imaging of white clover (Trifolium repens) leaves exposed to ozone gas. OCT image changes on each level of ozone damage were evaluated using parameters such as the OCT signal level of the leaf palisade layer, the thickness of the leaf palisade layer, and texture analysis using GLCM (Gray-Level Co-occurrence Matrix). Measurements of leaves grown in our laboratory showed increased palisade tissue signal, thicker palisade tissue, a smaller distribution of palisade layer thickness, increased OCT image contrast, and decreased OCT image homogeneity.
Tomographic imaging techniques offer new prospects for a better understanding of the quality, performance and release mechanisms of pharmaceutical solid dosage forms. It is only over the last fifteen years that tomography has been applied for the in-vitro characterisation of dosage forms. This review aims to introduce the concept of tomography in a pharmaceutical context, and describes the current state-of-the-art of the four most promising techniques: X-ray computed microtomography, magnetic resonance imaging, terahertz imaging and optical coherence tomography. The basic working principles of the techniques are introduced and the current pharmaceutical applications of the technologies are discussed, together with a comparison of their specific strengths and weaknesses. Possible future developments in these fields are also discussed.
This paper provides comparisons between microstructure and two-dimensional fiber orientations measured optically using polarization-sensitive optical coherence tomography (PS-OCT) and those estimated from ultra-high-field diffusion MRI (dMRI) at 10.5T in the macaque brain. The PS-OCT imaging is done at an in-plane resolution of ~10 microns in and around the thalamus. Whole brain dMRI is acquired at an isotropic resolution of 0.75 mm. We provide comparisons between cross-polarization and optical orientation from PS-OCT with the fractional anisotropy and two-dimensional orientations extracted from dMRI using a diffusion tensor model. The orientations from PS-OCT are also extracted computationally using a structure tensor. Additionally, we demonstrate the utility of mesoscale, PS-OCT imaging in improving the MRI resolution by learning the mapping between these contrasts using a super-resolution Generative Adversarial Network.
Volumetric data provide unprecedented structural insight to the reproductive tract and add vital anatomical context to the relationships between organs. The morphology of the female reproductive tract in non-avian reptiles varies between species, corresponding to a broad range of reproductive modes and providing valuable insight to comparative investigations of reproductive anatomy. However, reproductive studies in reptilian models, such as the brown anole studied here, have historically relied on histological methods to understand the anatomy. While these methods are highly effective for characterizing the cell types present in each organ, histological methods lose the 3D relationships between images and leave the architecture of the organ system poorly understood. We present the first comprehensive volumetric analyses of the female brown anole reproductive tract using two non-invasive, non-destructive imaging modalities: micro-computed tomography (microCT) and optical coherence to...
Purpose
To document the anatomical changes occurring at the vitreoretinal interface during early posterior vitreous detachment (PVD).
Methods
Wide-angle and pseudo-motion optical coherence tomography (OCT) were obtained on 27 normal eyes during the early stages of age-related PVD. The wide-angle examination in a static phase consisted of montaged conventional OCT images. GIF-formatted pseudo-animation was generated with OCT images acquired initially in a static eye state, followed by scans immediately after ocular excursions.
Results
Initial stages of PVD included peripheral PVD with (stage 1a) or without (stage 1b) interposed material between the posterior vitreous cortex and the retina, and perifoveal PVD expanding to the periphery (stage 2). All stage 1 PVDs presented anterior to the papillomacular vitreous liquefaction. All eyes demonstrated mobility of the vitreous gel at the anterior face of the vitreous liquefaction; however, the adherent cortical vitreous layer comprisi...
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