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    1. Artefact-removal algorithms for Fourier domain quantum optical coherence tomography

      Artefact-removal algorithms for Fourier domain quantum optical coherence tomography

      Quantum Optical Coherence Tomography (Q-OCT) is a non-classical equivalent of Optical Coherence Tomography and is able to provide a twofold axial resolution increase and immunity to resolution-degrading dispersion. The main drawback of Q-OCT are artefacts which are additional elements that clutter an A-scan and lead to a complete loss of structural information for multilayered objects. Whereas there are very practical and successful methods for artefact removal in Time-domain Q-OCT, no such scheme has been devised for Fourier-domain Q-OCT (Fd-Q-OCT), although the latter modality—through joint spectrum detection—outputs a lot of useful information on both the system and the imaged ...

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    2. Endomicroscopy of the human cochlea using a micro-optical coherence tomography catheter

      Endomicroscopy of the human cochlea using a micro-optical coherence tomography catheter

      Sensorineural hearing loss (SNHL) is one of the most profound public health concerns of the modern era, affecting 466 million people today, and projected to affect 900 million by the year 2050. Advances in both diagnostics and therapeutics for SNHL have been impeded by the human cochlea's inaccessibility for in vivo imaging, resulting from its extremely small size, convoluted coiled configuration, fragility, and deep encasement in dense bone. Here, we develop and demonstrate the ability of a sub-millimeter-diameter, flexible endoscopic probe interfaced with a micro-optical coherence tomography (μOCT) imaging system to enable micron-scale imaging of the inner ear's ...

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    3. Clinical features and prognosis of polypoidal choroidal vasculopathy with different morphologies of branching vascular network on optical coherence tomography angiography

      Clinical features and prognosis of polypoidal choroidal vasculopathy with different morphologies of branching vascular network on optical coherence tomography angiography

      This study highlights the clinical features and treatment response of polypoidal choroidal vasculopathy (PCV) among three different branching vascular network (BVN) morphologies in optical coherence tomography angiography (OCTA), and further correlates the BVN features with those under fluorescent angiography (FA) and indocyanine green angiography (ICGA). In total, we reviewed 70 eyes with PCV followed up for > 12 months. OCTA, ICGA and FA images were obtained at baseline and post-treatments. BVN was assessed using OCTA and divided into three types by a previously described BVN classification: type 1 (trunk), type 2 (glomeruli), and type 3 (stick). At baseline, type 1 BVN ...

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    4. Prediction of trabecular meshwork-targeted micro-invasive glaucoma surgery outcomes using anterior segment OCT angiography

      Prediction of trabecular meshwork-targeted micro-invasive glaucoma surgery outcomes using anterior segment OCT angiography

      We performed a prospective, longitudinal study to investigate the association between the preoperative intrascleral vasculature assessed using anterior segment (AS)-optical coherence tomography angiography (OCTA) and surgical outcomes of trabecular meshwork-targeted micro- or minimally invasive glaucoma surgery (MIGS). We included 37 patients with primary open-angle glaucoma. Preoperative AS-OCTA images of the sclero-conjunctiva of the nasal corneal limbus were acquired in the superficial (conjunctival) and deep (intrascleral) layers. The vessel densities (VDs) of each layer were measured separately in the entire area, limbal side, and fornix area. Surgical success was determined by postoperative intraocular pressure (IOP) and IOP reduction. Twenty-three and ...

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    5. Optical coherence tomography angiography (OCTA) of retinal vasculature in patients with post fever retinitis: a qualitative and quantitative analysis

      Optical coherence tomography angiography (OCTA) of retinal vasculature in patients with post fever retinitis: a qualitative and quantitative analysis

      Post fever retinitis is a heterogenous entity that is seen 2-4 weeks after a systemic febrile illness in an immunocompetent individual. It may occur following bacterial, viruses, or protozoal infection. Optical coherence angiography (OCTA) is a newer non-invasive modality that is an alternative to fundus fluorescein angiography to image the retinal microvasculature. We hereby describe the vascular changes during the acute phase of post fever retinitis on OCTA. Imaging on OCTA was done for all patients with post fever retinitis at presentation with 3 × 3 mm and 8 × 8 mm scans centred on the macula and corresponding enface optical coherence ...

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    6. Optical coherence tomographic angiography study of perfusion recovery after surgical lowering of intraocular pressure

      Optical coherence tomographic angiography study of perfusion recovery after surgical lowering of intraocular pressure

      We investigated the time and location of retinal perfusion recovery after surgical intraocular pressure (IOP) lowering in glaucoma by using optical coherent tomography angiography (OCTA). Seventeen patients were analyzed. The 4.5 × 4.5-mm OCTA scans centered on the disc were performed preoperatively and postoperatively at 6 weeks, 3 months, and 6 months. The peripapillary retinal nerve fiber layer (NFL) thickness, NFL plexus capillary density (NFLP-CD) and visual field (VF) were measured overall and in 8 corresponding sectors. The low-perfusion area (LPA) was used to assess the cumulative area where local NFLP-CD was significantly below normal. At 6 months, the ...

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    7. Characterizing right-angled vessel in macular telangiectasia type 2 with structural optical coherence tomography

      Characterizing right-angled vessel in macular telangiectasia type 2 with structural optical coherence tomography

      We investigated the structural findings on spectral-domain optical coherence tomography (SD-OCT) related to the presence of right-angled vessels (RAV) in patients with macular telangiectasia (MacTel) type 2 with severity 3 in Korea. A retrospective multicenter cross-sectional study was conducted in six tertiary hospitals in Korea; the study included 116 MacTel type 2 eyes with severity 3. The SD-OCT findings were compared between eyes with RAV on fundus photography or fluorescein angiography and those without RAV. Logistic regression was performed to determine factors associated with the presence of RAV. Fifty eyes presented with RAV and 61 eyes without RAV. More eyes ...

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    8. Comparison of multicolor scanning laser ophthalmoscopy and optical coherence tomography angiography for detection of microaneurysms in diabetic retinopathy

      Comparison of multicolor scanning laser ophthalmoscopy and optical coherence tomography angiography for detection of microaneurysms in diabetic retinopathy

      This study aimed to evaluate the usefulness of multicolor (MC) scanning laser ophthalmoscopy (MC-SLO) in detecting microaneurysm (MA) in eyes with diabetic retinopathy (DR). This was a retrospective cross-sectional study. Eyes with DR underwent fluorescein angiography (FA), MC-SLO, optical coherence tomography angiography (OCTA), and color fundus photography (CFP) were analyzed. The foveal region was cut in an 6 × 6 mm image and the number of MA in each image was counted by retina specialists to determine the sensitivity and positive predictive value. FA results were used as the ground standard. MAs were classified as those with early, late, or no ...

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    9. Self-assembling human heart organoids for the modeling of cardiac development and congenital heart disease | Nature Communications

      Self-assembling human heart organoids for the modeling of cardiac development and congenital heart disease | Nature Communications

      Congenital heart defects constitute the most common human birth defect, however understanding of how these disorders originate is limited by our ability to model the human heart accurately in vitro. Here we report a method to generate developmentally relevant human heart organoids by self-assembly using human pluripotent stem cells. Our procedure is fully defined, efficient, reproducible, and compatible with high-content approaches. Organoids are generated through a three-step Wnt signaling modulation strategy using chemical inhibitors and growth factors. Heart organoids are comparable to age-matched human fetal cardiac tissues at the transcriptomic, structural, and cellular level. They develop sophisticated internal chambers with ...

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    10. Accessing depth-resolved high spatial frequency content from the optical coherence tomography signal

      Accessing depth-resolved high spatial frequency content from the optical coherence tomography signal

      Optical coherence tomography (OCT) is a rapidly evolving technology with a broad range of applications, including biomedical imaging and diagnosis. Conventional intensity-based OCT provides depth-resolved imaging with a typical resolution and sensitivity to structural alterations of about 5–10 microns. It would be desirable for functional biological imaging to detect smaller features in tissues due to the nature of pathological processes. In this article, we perform the analysis of the spatial frequency content of the OCT signal based on scattering theory. We demonstrate that the OCT signal, even at limited spectral bandwidth, contains information about high spatial frequencies present in ...

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    11. The structure-function correlation analysed by OCT and full field ERG in typical and pericentral subtypes of retinitis pigmentosa

      The structure-function correlation analysed by OCT and full field ERG in typical and pericentral subtypes of retinitis pigmentosa

      To investigate the structure-function correlation analysed by full-field electroretinography (ffERG) and optical coherence tomography (OCT) in typical and pericentral subtypes of retinitis pigmentosa (RP). A retrospective, cross-sectional, observational study of right eyes was conducted. The primary analysis used ffERG data to compare the RP subtypes. The subgroup analysis was used to correlate the structure, analysed by OCT, and function, determined by ffERG. Linear regressions explored the relationship between best-corrected visual acuity (BCVA) and multiple parameters. A total of 188 eyes were included. Amplitudes of responses of rod, rod-cone, cone, and 30 Hz flicker of typical type were lower than those ...

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    12. Phase stable swept-source optical coherence tomography with active mode-locking laser for contrast enhancements of retinal angiography

      Phase stable swept-source optical coherence tomography with active mode-locking laser for contrast enhancements of retinal angiography

      Swept-source optical coherence tomography (SS-OCT) is an attractive high-speed imaging technique for retinal angiography. However, conventional swept lasers vary the cavity length of the laser mechanically to tune the output wavelength. This causes sweep-timing jitter and hence low phase stability in OCT angiography. Here, we improve an earlier phase-stabilized, akinetic, SS-OCT angiography (OCTA) method by introducing coherent averaging. We develop an active mode-locking (AML) laser as a high phase-stable akinetic swept source for the OCTA system. The phase stability of the improved system was analyzed, and the effects of coherent averaging were validated using a retina phantom. The effectiveness of ...

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    13. Role of anterior segment optical coherence tomography angiography in the assessment of acute chemical ocular injury: a pilot animal model study

      Role of anterior segment optical coherence tomography angiography in the assessment of acute chemical ocular injury: a pilot animal model study

      To examine the use of anterior segment-optical coherence tomography angiography (AS-OCTA) in the assessment of limbal ischemia in an animal model chemical ocular injury. We conducted a prospective study using an established chemical ocular injury model in 6 rabbits (12 eyes), dividing the cornea limbus into 4 quadrants. Chemical injury grade was induced based on extent of limbal injury (0 to 360 degrees) and all eyes underwent serial slit-lamp with AS-OCTA imaging up to one month. Main outcome measure was changes in AS-OCTA vessel density (VD) comparing injured and control cornea limbal quadrants within 24 h and at one month ...

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    14. Towards a better understanding of the posttreatment hemodynamic behaviors in femoropopliteal arteries through personalized computational models based on OCT images

      Towards a better understanding of the posttreatment hemodynamic behaviors in femoropopliteal arteries through personalized computational models based on OCT images

      The hemodynamic behavior following endovascular treatment of patients with peripheral arterial disease plays a significant role on the occurrence of restenosis in femoro-popliteal (FP) arteries. The atheroprone flow conditions that are generally accepted to promote restenosis can be calculated by computational fluid dynamics (CFD) analyses, and these results can be used to assess individualized treatment outcomes. However, the impact of endovascular therapy on the flow behaviors of FP arteries are still poorly understood, as the imaging modalities used in existing numerical works (X-ray angiography, computed tomography angiography) are unable to accurately represent the post-treatment arterial geometry due to their low ...

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    15. Dependency of hydration and growth conditions on the mechanical properties of oral biofilms

      Dependency of hydration and growth conditions on the mechanical properties of oral biofilms

      Within the oral cavity, dental biofilms experience dynamic environments, in part due to changes in dietary content, frequency of intake and health conditions. This can impact bacterial diversity and morpho-mechanical properties. While phenotypic properties of oral biofilms are closely related to their composition, these can readily change according to dynamic variations in the growth environment and nutrient availability. Understanding the interlink between phenotypic properties, variable growth conditions, and community characterization is an essential requirement to develop structure–property relationships in oral-biofilms. In this study, the impact of two distinct growth media types with increasing richness on the properties of oral ...

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    16. The role of choroidal optical coherence tomography for follow-up of carotid cavernous fistula with anterior drainage

      The role of choroidal optical coherence tomography for follow-up of carotid cavernous fistula with anterior drainage

      Background To evaluate the role of the choroidal vascularity index (CVI) and the tortuosity index (TI), along with choroidal thickness measurements, in follow-up for anteriorly draining carotid cavernous fistulas (CCF) that would otherwise necessitate an invasive carotid angiogram. Methods In this longitudinal observational study, analysis of enhanced depth imaging spectral domain optical coherence tomography (SD-EDI-OCT) images of 22 patients with angiographically proven unilateral CCF with anterior drainage was performed for subfoveal choroidal thickness (SFCT), central foveal thickness (CFT), CVI and TI. Baseline measurements were compared with those taken at the last visit after occlusion of the fistula. Results Both in ...

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    17. Fundus autofluorescence and optical coherence tomography biomarkers associated with the progression of geographic atrophy secondary to age-related macular degeneration

      Fundus autofluorescence and optical coherence tomography biomarkers associated with the progression of geographic atrophy secondary to age-related macular degeneration

      Objectives To investigate the impact of qualitatively graded and deep learning quantified imaging biomarkers on growth of geographic atrophy (GA) secondary to age-related macular degeneration. Methods This prospective study included 1062 visits of 181 eyes of 100 patients with GA. Spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) images were acquired at each visit. Hyperreflective foci (HRF) were quantitatively assessed in SD-OCT volumes using a validated deep learning algorithm. FAF images were graded for FAF patterns, subretinal drusenoid deposits (SDD), GA lesion configuration and atrophy enlargement. Linear mixed models were calculated to investigate associations between all parameters and GA ...

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    18. Photoreceptor outer segment layer contributes to optical coherence tomography signal attenuation beneath neurosensory detachments

      Photoreceptor outer segment layer contributes to optical coherence tomography signal attenuation beneath neurosensory detachments

      Purpose To establish the factors responsible for attenuation of the optical coherence tomography (OCT) signal beneath the neurosensory detachment (NSD). Methods We retrospectively reviewed 33 eyes with acute central serous chorioretinopathy. The thickness of the neurosensory retina, the thickness of the photoreceptor outer segment (PROS) layer, the height of the NSD, and the reflectivity of the underlying retinal pigment epithelium (RPE) were measured at selected points of B-scans exported from 6 × 6 mm OCT angiography protocols. The intensity of the flow signal was measured at the corresponding regions of the choriocapillaris slab. The correlation between the parameters of the NSD ...

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    19. Cerebral malaria: insight into pathology from optical coherence tomography

      Cerebral malaria: insight into pathology from optical coherence tomography

      We aimed to investigate structural retinal changes in malarial retinopathy (MR) using hand-held optical coherence tomography (HH-OCT) to assess its diagnostic potential. Children with MR (n = 43) underwent ophthalmoscopy, fluorescein angiography and HH-OCT during admission, 1-month (n = 31) and 1-year (n = 8) post-discharge. Controls were comatose patients without malaria (n = 6) and age/sex-matched healthy children (n = 43). OCT changes and retinal layer thicknesses were compared. On HH-OCT, hyper-reflective areas (HRAs) were seen in the inner retina of 81% of MR patients, corresponding to ischaemic retinal whitening on fundus photography. Cotton wool spots were present in 37% and abnormal hyper-reflective ...

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    20. OCTA reveals remodeling of the peripheral capillary free zones in normal aging

      OCTA reveals remodeling of the peripheral capillary free zones in normal aging

      The retinal neurovascular unit consists of blood vessel endothelial cells, pericytes, neurons, astrocytes, and Müller cells that form the inner retinal blood barrier. A peripheral capillary free zone (pCFZ) represents the distance that oxygen and nutrients must diffuse to reach the neural retina, and serves as a metric of retinal tissue oxygenation. The pCFZs are formed based on oxygen saturation in the retinal arterioles and venules. Because retinal arterioles contain a larger concentration of oxygenated blood than venules, there is a reduced need for capillaries to exist closely to arterioles compared to venules. Therefore, in a healthy individual, larger ...

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      Mentions: Brown University
    21. Correlation of choriocapillaris hemodynamic data from dynamic indocyanine green and optical coherence tomography angiography

      Correlation of choriocapillaris hemodynamic data from dynamic indocyanine green and optical coherence tomography angiography

      To investigate the correlation between posterior pole choroidal blood flow evaluated with digital subtraction indocyanine green angiography and enface optical coherence tomography angiography (OCTA). Imaging in animal study. The anatomy of 2 cynomogulus monkeys was studied. Each monkey was given a 0.75 mg/kg injection of indocyanine green in the saphenous vein. The dynamic angiographic filling sequence was recorded at 15 frames per second using the Heidelberg Spectralis. After image registration, sequential frame subtraction was used to image the dye front moving through the choroid. The OCTA was obtained by frame averaging nine separate choriocapillaris slab flow images obtained ...

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    22. Manually scanned single fiber optical coherence tomography for skin cancer characterization

      Manually scanned single fiber optical coherence tomography for skin cancer characterization

      Optical coherence tomography (OCT) is a cross-sectional imaging modality based on low coherence light interferometry. Within dermatology, it has found applications for in vivo diagnostic imaging purposes, as well as to guide Mohs micrographic surgery (MMS), due to its ability to visualize skin morphology up to several millimeters in depth. However, standard OCT probes have a large footprint and capture an extended area of the skin, making it difficult to precisely pinpoint clinically relevant location being imaged. Mohs surgeons stand to benefit from a handheld in vivo imaging device that can accurately trace surgical margins. In this study, we demonstrate ...

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    23. New algorithm for corneal densitometry assessment based on anterior segment optical coherence tomography

      New algorithm for corneal densitometry assessment based on anterior segment optical coherence tomography

      Purpose To describe a new algorithm to measure corneal densitometry based on images obtained by swept source anterior segment ocular coherence tomography (SS-AS-OCT) and establish standard densitometry values in a group of normal eyes. Methods A total of 111 healthy participants (195 eyes) were enrolled in this study. Using a MATLAB designed algorithm, the cornea was segmented into three layers: anterior, posterior and mid-stroma, and it was divided into two concentric areas, 0–2 and 2–4 mm, resulting in nine areas for the analysis. The mean corneal densitometry values were calculated and expressed as grayscale units (GSU). Results The ...

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    24. Evaluation of retinal vascular density and related factors in youth myopia without maculopathy using OCTA

      Evaluation of retinal vascular density and related factors in youth myopia without maculopathy using OCTA

      To evaluate the retinal vascular flow density changes of myopic eyes of young adults using optical coherence tomography angiography and the factors affecting these changes. In this cross-sectional study, 90 eyes of 45 participants were analyzed and divided into three groups: mild, moderate, and high myopia (without pathological changes). Macular and radial peripapillary capillary flow densities were measured using optical coherence tomography angiography. Their relationships with the axial length, the spherical equivalent of the refractive error, and age were analyzed using analysis of variance, Pearson's correlation coefficient, and multivariate linear regression analysis. Superficial and deep macular vascular densities were ...

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