1. Articles from David Huang

    1-24 of 271 1 2 3 4 ... 10 11 12 »
    1. Volume-based, layer-independent, disease-agnostic detection of abnormal retinal reflectivity, nonperfusion, and neovascularization using structural and angiographic OCT

      Volume-based, layer-independent, disease-agnostic detection of abnormal retinal reflectivity, nonperfusion, and neovascularization using structural and angiographic OCT

      Optical coherence tomography (OCT) is widely used in ophthalmic practice because it can visualize retinal structure and vasculature in vivo and 3-dimensionally (3D). Even though OCT procedures yield data volumes, clinicians typically interpret the 3D images using two-dimensional (2D) data subsets, such as cross-sectional scans or en face projections. Since a single OCT volume can contain hundreds of cross-sections (each of which must be processed with retinal layer segmentation to produce en face images), a thorough manual analysis of the complete OCT volume can be prohibitively time-consuming. Furthermore, 2D reductions of the full OCT volume may obscure relationships between disease ...

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    2. Systems and methods for automated widefield optical coherence tomography angiography

      Systems and methods for automated widefield optical coherence tomography angiography

      Disclosed are systems and methods for generating wide-field optical coherence tomography angiography (OCTA) images. In embodiments, multiple OCTA scans of a sample are automatically acquired at overlapping locations. The systems and methods include functionality to adaptively control the scanning procedure such that eye blink and eye motion events are detected in real time and accounted for during 3D scan acquisition. Also disclosed are methods for detecting and correcting motion-related artifacts in OCTA datasets which allow for the longer scan times over larger fields of view required for wide-field imaging. These methods may include division of en face angiogram images into ...

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    3. Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

      Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

      Purpose : The purpose of this study was to correct refractive error-associated bias in optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters. Methods : OCT and OCTA imaging were obtained from participants in the Hong Kong FAMILY cohort. The Avanti/AngioVue OCT/OCTA system was used to measure the peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), macular ganglion cell complex thickness (GCCT), and macular superficial vascular complex vascular density (SVC-VD). Healthy eyes, including ones with axial ametropia, were enrolled for analysis. Results : A total of 1346 eyes from 792 participants were divided ...

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    4. Corneal imaging with blue-light optical coherence microscopy

      Corneal imaging with blue-light optical coherence microscopy

      Corneal imaging is important for the diagnostic and therapeutic evaluation of many eye diseases. Optical coherence tomography (OCT) is extensively used in ocular imaging due to its non-invasive and high-resolution volumetric imaging characteristics. Optical coherence microscopy (OCM) is a technical variation of OCT that can image the cornea with cellular resolution. Here, we demonstrate a blue-light OCM as a low-cost and easily reproducible system to visualize corneal cellular structures such as epithelial cells, endothelial cells, keratocytes, and collagen bundles within stromal lamellae. Our blue-light OCM system achieved an axial resolution of 12 µm in tissue over a 1.2 mm ...

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    5. Detection of Corneal Ectasia Using OCT Maps of Pachymetry and Posterior Surface Mean Curvature

      Detection of Corneal Ectasia Using OCT Maps of Pachymetry and Posterior Surface Mean Curvature

      Purpose: To quantify the abnormal corneal thinning and posterior surface steepening that is observed in keratoconus with an Ectasia Index. Methods: Optical coherence tomography (OCT) was used to image the corneas of normal individuals and patients with varying stages of keratoconus (manifest, subclinical, and forme fruste). Maps of corneal pachymetry and posterior surface mean curvature were generated, and an Ectasia Index was calculated by multiplying Gaussian fits obtained from the two types of maps. Repeated five-fold cross-validation was used to evaluate the ability of the Ectasia Index to differentiate between normal and keratoconic eyes. The classification performance of the Ectasia ...

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    6. Widefield Optical Coherence Tomography in Pediatric Retina: A Case Series of Intraoperative Applications Using a Prototype Handheld Device

      Widefield Optical Coherence Tomography in Pediatric Retina: A Case Series of Intraoperative Applications Using a Prototype Handheld Device

      Optical coherence tomography (OCT) has changed the standard of care for diagnosis and management of macular diseases in adults. Current commercially available OCT systems, including handheld OCT for pediatric use, have a relatively narrow field of view (FOV), which has limited the potential application of OCT to retinal diseases with primarily peripheral pathology, including many of the most common pediatric retinal conditions. More broadly, diagnosis of all types of retinal detachment (exudative, tractional, and rhegmatogenous) may be improved with OCT-based assessment of retinal breaks, identification of proliferative vitreoretinopathy (PVR) membranes, and the pattern of subretinal fluid. Intraocular tumors both benign ...

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    7. A Diabetic Retinopathy Classification Framework Based on Deep-Learning Analysis of OCT Angiography

      A Diabetic Retinopathy Classification Framework Based on Deep-Learning Analysis of OCT Angiography

      Purpose : Reliable classification of referable and vision threatening diabetic retinopathy (DR) is essential for patients with diabetes to prevent blindness. Optical coherence tomography (OCT) and its angiography (OCTA) have several advantages over fundus photographs. We evaluated a deep-learning-aided DR classification framework using volumetric OCT and OCTA. Methods : Four hundred fifty-six OCT and OCTA volumes were scanned from eyes of 50 healthy participants and 305 patients with diabetes. Retina specialists labeled the eyes as non-referable (nrDR), referable (rDR), or vision threatening DR (vtDR). Each eye underwent a 3 × 3-mm scan using a commercial 70 kHz spectral-domain OCT system. We developed a ...

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    8. Measuring Corneal Astigmatism Using Optical Coherence Tomography in Keratoconus

      Measuring Corneal Astigmatism Using Optical Coherence Tomography in Keratoconus

      Purpose: To measure net corneal astigmatism using optical coherence tomography (OCT, Avanti, Optovue) in individuals with keratoconus and compare its repeatability and accuracy with those obtained using Scheimpflug imaging (Pentacam HR, Oculus). Setting: Casey Eye Institute, Portland, Oregon, USA. Design: Prospective cross-sectional observational study. Methods: Net corneal astigmatism was calculated in keratoconic and normal eyes with OCT and Scheimpflug imaging using four settings - pupil or vertex centration settings with a 3 or 4 mm circular analytical zone. Corneal elevation maps were obtained from OCT images and fitted with Zernike polynomials to obtain net corneal astigmatism. Manifest refraction astigmatism was used ...

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    9. Automated detection of shadow artifacts in optical coherence tomography angiography

      Automated detection of shadow artifacts in optical coherence tomography angiography

      Disclosed herein are methods and systems for automated detection of shadow artifacts in optical coherence tomography (OCT) and/or OCT angiography (OCTA). The shadow detection includes applying a machine-learning algorithm to the OCT dataset and the OCTA dataset to detect one or more shadow artifacts in the sample. The machine-learning algorithm is trained with first training data from first training samples that include manufactured shadows and no perfusion defects and second training data from second training samples that include perfusion defects and no manufactured shadows. The shadow artifacts in the OCTA dataset and/or OCT dataset may be suppressed to ...

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    10. Postdoctoral Research Position at Oregon Health & Science University

      Postdoctoral Research Position at Oregon Health & Science University

      A postdoctoral research fellow/research associate position is immediately available at the Center for Ophthalmic Optics and Lasers ( www.COOLLab.net ), Casey Eye Institute, Oregon Health & Science University. The postdoc will develop novel ophthalmic imaging instruments and analytic algorithms to advance the measurement of ocular structure and function. Ph.D. in Optics, Electrical Engineering, Computer Science, Biomedical Engineering, or a related field is required. The successful applicant will demonstrate a strong motivation for innovative, translational research that can positively impact the care and management of eye diseases. The candidate is expected to have demonstrated strong expertise in one or more ...

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    11. Postdoctoral Research Fellowship in Anterior Eye OCT Image Processing and Machine Learning at Oregon Health & Science University.

      Postdoctoral Research Fellowship in Anterior Eye OCT Image Processing and Machine Learning at Oregon Health & Science University.

      A postdoctoral research fellow position is immediately available in the Center for Ophthalmic Optics & Lasers Lab ( www.coollab.net ), Casey Eye Institute, Oregon Health & Science University. The fellowship will focus on interdisciplinary projects in the field of biomedical image processing, visual optics, and machine learning. PhD in Biomedical Engineering, Electrical Engineering, Computer Science, Optics, or related field of research is required. The position is supported by NIH/NEI research grants to apply optical coherence tomography (OCT), OCT angiography, and optical coherence elastography on anterior eye disease evaluation. Machine learning approaches will be used for disease classification. Demonstrated excellence in one ...

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    12. Differentiating Between Contact Lens Warpage and Keratoconus Using OCT Maps of Corneal Mean Curvature and Epithelial Thickness

      Differentiating Between Contact Lens Warpage and Keratoconus Using OCT Maps of Corneal Mean Curvature and Epithelial Thickness

      Purpose: To formulate an Epithelial Modulation index to differentiate between eyes with contact lens warpage and keratoconus. Methods: Normal eyes and eyes with either contact lens warpage or keratoconus were scanned by a Fourier-domain optical coherence tomography (OCT) system. Maps of epithelial thickness and anterior surface mean curvature were generated and converted to deviation maps by subtracting the average maps from a healthy population. The Epithelial Modulation index was defined as the covariance between the two types of deviation maps. A logistic regression model was used to classify eyes as non-keratoconus (normal or warp-age) or keratoconus (manifest, subclinical, or forme ...

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    13. Peripheral OCT Assisted by Scleral Depression in Retinopathy of Prematurity

      Peripheral OCT Assisted by Scleral Depression in Retinopathy of Prematurity

      Objective: To determine whether handheld widefield optical coherence tomography (OCT) can be used to document retinopathy of prematurity (ROP) stage while using scleral depression to improve peripheral views. Design: Prospective observational study. Participants: Consecutive neonates admitted to the neonatal intensive care unit (NICU) in a single academic medical center who also met criteria for ROP screening and consented for research imaging. Methods: Scleral depression was combined with widefield OCT using an investigational 400-kHz, 55-degree field of view handheld OCT during routine ROP screening from October 28, 2020 to March 03, 2021. Main outcome measures: Acquisition of en face and B-scan ...

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    14. Advantages of Widefield Optical Coherence Tomography in the Diagnosis of Retinopathy of Prematurity

      Advantages of Widefield Optical Coherence Tomography in the Diagnosis of Retinopathy of Prematurity

      Recent advances in portable optical coherence tomography (OCT) and OCT angiography (OCTA) have resulted in wider fields of view (FOV) and shorter capture times, further expanding the potential clinical role of OCT technology in the diagnosis and management of retinopathy of prematurity (ROP). Using a prototype, handheld OCT device, retinal imaging was obtained in non-sedated infants in the neonatal intensive care unit (NICU) as well as sedated infants in the operating room of Oregon Health & Science University (OHSU) Hospital. In this observational study, we provide an overview of potential advantages of OCT-based disease assessment in ROP. We observed that next-generation ...

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    15. High speed, long range, deep penetration swept source OCT for structural and angiographic imaging of the anterior eye

      High speed, long range, deep penetration swept source OCT for structural and angiographic imaging of the anterior eye

      This study reports the development of prototype swept-source optical coherence tomography (SS-OCT) technology for imaging the anterior eye. Advances in vertical-cavity surface-emitting laser (VCSEL) light sources, signal processing, optics and mechanical designs, enable a unique combination of high speed, long range, and deep penetration that addresses the challenges of anterior eye imaging. We demonstrate SS-OCT with a 325 kHz A-scan rate, 12.2 µm axial resolution (in air), and 15.5 mm depth range (in air) at 1310 nm wavelength. The ultrahigh 325 kHz A-scan rate not only facilitates biometry measurements by minimizing acquisition time and thus reducing motion, but ...

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    16. Volumetric directional optical coherence tomography

      Volumetric directional optical coherence tomography

      Photoreceptor loss and resultant thinning of the outer nuclear layer (ONL) is an important pathological feature of retinal degenerations and may serve as a useful imaging biomarker for age-related macular degeneration. However, the demarcation between the ONL and the adjacent Henle’s fiber layer (HFL) is difficult to visualize with standard optical coherence tomography (OCT). A dedicated OCT system that can precisely control and continuously and synchronously update the imaging beam entry points during scanning has not been realized yet. In this paper, we introduce a novel imaging technology, Volumetric Directional OCT (VD-OCT), which can dynamically adjust the incident beam ...

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    17. 105° field of view non-contact handheld swept-source optical coherence tomography

      105° field of view non-contact handheld swept-source optical coherence tomography

      We demonstrate a handheld swept-source optical coherence tomography (OCT) system with a 400 kHz vertical-cavity surface-emitting laser (VCSEL) light source, a non-contact approach, and an unprecedented single shot 105° field of view (FOV). We also implemented a spiral scanning pattern allowing real-time visualization with improved scanning efficiency. To the best of our knowledge, this is the widest FOV achieved in a portable non-contact OCT retinal imaging system to date. Improvements to the FOV may aid the evaluation of retinal diseases such as retinopathy of prematurity, where important vitreoretinal changes often occur in the peripheral retina.

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    18. Prospective evaluation of optical coherence tomography for disease detection in the Casey mobile eye clinic

      Prospective evaluation of optical coherence tomography for disease detection in the Casey mobile eye clinic

      This study was designed to evaluate iVue Spectral-domain optical coherence tomography (SD-OCT) effectiveness in screening for eye disease compared to clinical examination. Subjects were recruited from the Casey Eye Community Outreach Program Mobile Clinic during its routinely scheduled outreach clinics to indigent, underserved populations throughout Oregon. Macular optical coherence tomography interpretation and automated optical coherence tomography analysis were compared to the clinical examination, with specific attention to findings indicative of retinal abnormalities, risks for glaucoma, and narrow angles. As a result, a total of 114 subjects were included in this study. In diabetics, optical coherence tomography and clinical exam were ...

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    19. High-Speed, Long-Range Swept-Source Optical Coherence Tomography for the Anterior Segment of the Eye

      High-Speed, Long-Range Swept-Source Optical Coherence Tomography for the Anterior Segment of the Eye

      Purpose : The anterior segment (AS) of the eye is of interest in multiple diseases and procedures, including glaucoma, ocular surface inflammation, and refractive / cataract surgeries. Visualizing the anterior eye using optical coherence tomography (OCT) has unique challenges, and AS OCT technology is less developed than retinal imaging. We developed next generation swept-source OCT (SS-OCT) technology to enable high-speed and long-range AS structural and angiographic imaging in clinical settings. Methods : We designed a SS-OCT prototype instrument using wavelength-tunable, vertical-cavity surface-emitting laser (VCSEL) with linearized frequency sweep. The OCT wavelength centers at 1310 nm with a 105 nm bandwidth. The A-scan rate ...

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    20. 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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    21. Accuracy of OCT-derived net corneal astigmatism measurement

      Accuracy of OCT-derived net corneal astigmatism measurement

      Purpose: To assess the repeatability and accuracy of corneal astigmatism measurement with a spectral-domain optical coherence tomography (OCT) system (Avanti, Optovue) and compare them with Scheimpflug imaging (Pentacam HR, Oculus) and swept-source optical biometry (IOLMaster 700, Carl Zeiss Mediatec AG). Setting: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA. Design: Prospective cross-sectional observational study. Methods: Sixty pseudophakic eyes with monofocal non-toric intraocular lens that previously had refractive surgery were analyzed. To assess accuracy, simulated keratometric (SimK) and net corneal astigmatism, obtained from each device were compared with subjective manifest refraction astigmatism. Repeatability for corneal astigmatism was assessed for ...

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    22. Effect of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography

      Effect of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography

      Purpose: To assess the effects of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography (OCTA). Methods: In this prospective cross-sectional study, one eye each of 36 normal controls and 64 patients with glaucoma underwent 4.5 mm disc-centred and 6 mm macula-centred OCTA scans. The peripapillary nerve fibre layer plexus capillary density (NFLP-CD) and macular superficial vascular complex vessel density (SVC-VD) were measured using both a commercial algorithm (AngioAnalytics) and a custom algorithm (Center for Ophthalmic Optics & Lasers Angiography Reading Toolkit (COOL-ART)). The nerve fibre layer and ganglion cell complex thicknesses were measured on structural OCT. Results ...

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    23. Cognitive decline in older adults: What can we learn from optical coherence tomography (OCT)-based retinal vascular imaging?

      Cognitive decline in older adults: What can we learn from optical coherence tomography (OCT)-based retinal vascular imaging?

      Introduction: Accumulated vascular damage contributes to the onset and progression of vascular dementia and possibly to Alzheimer's disease. Here we evaluate the feasibility and utility of using retinal imaging of microvascular markers to identify older adults at risk of cognitive disease. Methods: The "Eye Determinants of Cognition" (EyeDOC) study recruited a biracial, population-based sample of participants from two sites: Jackson, MS, and Washington Co, MD. Optical coherence tomographic angiography (OCTA) was used to capture vessel density (VD) from a 6 × 6 mm scan of the macula in several vascular layers from 2017 to 2019. The foveal avascular zone (FAZ ...

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    24. High-speed and widefield handheld swept-source OCT angiography with a VCSEL light source

      High-speed and widefield handheld swept-source OCT angiography with a VCSEL light source

      Optical coherence tomography (OCT) and OCT angiography (OCTA) enable noninvasive structural and angiographic imaging of the eye. Portable handheld OCT/OCTA systems are required for imaging patients in the supine position. Examples include infants in the neonatal intensive care unit (NICU) and operating room (OR). The speed of image acquisition plays a pivotal role in acquiring high-quality OCT/OCTA images, particularly with the handheld system, since both the operator hand tremor and subject motion can cause significant motion artifacts. In addition, having a large field of view and the ability of real-time data visualization are critical elements in rapid disease ...

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