1. Articles from David Huang

    1-24 of 264 1 2 3 4 ... 9 10 11 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. 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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    15. 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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    16. 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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    17. 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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    18. Comparison of Central Macular Fluid Volume With Central Subfield Thickness in Patients With Diabetic Macular Edema Using Optical Coherence Tomography Angiography

      Comparison of Central Macular Fluid Volume With Central Subfield Thickness in Patients With Diabetic Macular Edema Using Optical Coherence Tomography Angiography

      Importance: Diabetic macular edema (DME) is the predominant cause of visual impairment in patients with type 1 or 2 diabetes. Automated fluid volume measurements using optical coherence tomography (OCT) may improve the diagnostic accuracy of DME screening. Objective: To assess the diagnostic accuracy of an automated central macular fluid volume (CMFV) quantification using OCT for DME. Design, setting, and participants: A cross-sectional observational study was conducted at a tertiary academic center among 215 patients with diabetes (1 eye each) enrolled from January 26, 2015, to December 23, 2019. All participants underwent comprehensive examinations, 6 × 6-mm macular structural OCT horizontal raster ...

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    19. Plexus-specific retinal vascular anatomy and pathologies as seen by projection-resolved optical coherence tomographic angiography

      Plexus-specific retinal vascular anatomy and pathologies as seen by projection-resolved optical coherence tomographic angiography

      Optical coherence tomographic angiography (OCTA) is a novel technology capable of imaging retinal vasculature three-dimensionally at capillary scale without the need to inject any extrinsic dye contrast. However, projection artifacts cause superficial retinal vascular patterns to be duplicated in deeper layers, thus interfering with the clean visualization of some retinal plexuses and vascular pathologies. Projection-resolved OCTA (PR-OCTA) uses post-processing algorithms to reduce projection artifacts. With PR-OCTA, it is now possible to resolve up to 4 distinct retinal vascular plexuses in the living human eye. The technology also allows us to detect and distinguish between various retinal and optic nerve diseases ...

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    20. Plexus-specific retinal capillary avascular area in exudative age-related macular degeneration with projection-resolved OCT angiography

      Plexus-specific retinal capillary avascular area in exudative age-related macular degeneration with projection-resolved OCT angiography

      Objective To detect the plexus-specific retinal capillary avascular area in exudative age-related macular degeneration (EAMD) with projection-resolved optical coherence tomography angiography (PR-OCTA). Methods and analysis In this prospective cross-sectional single centre study, eyes with treatment-naïve EAMD underwent macular 3×3 mm OCTA with AngioVue system. OCTA scans were analysed and processed including three-dimensional projection artefact removal, retinal layer semi-automated segmentation and en face angiogram generation. Automated quantification of extrafoveal (excluding the central 1 mm circle) avascular area (EAA) were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP) and deep capillary plexus (DCP), respectively. Results Nineteen eyes ...

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    21. Optical Instrumentation Position Opening at Oregon Health & Science University

      Optical Instrumentation Position Opening at Oregon Health & Science University

      Two postdoctoral research fellowship/research associate positions are immediately available in the Center for Ophthalmic Optics and Lasers www.COOLLab.net, Casey Eye Institute, Oregon Health & Science University. The fellowship will focus on interdisciplinary project in the field of optical imaging and image processing. Ph.D. in Optics, Biomedical Engineering, Electrical Engineering, Computing Science or a related field is required. Demonstrated excellence in one or more of the following areas is preferred: expertise in Optical Coherence Tomography, Scanning Laser Ophthalmoscope and Adaptive Optics, optical/electrical system design, prototyping and simulation, data acquisition and system control/synchronization, and C++/GPU programming ...

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    22. Keratoconus Detection using OCT Corneal and Epithelial Thickness Map Parameters and Patterns

      Keratoconus Detection using OCT Corneal and Epithelial Thickness Map Parameters and Patterns

      Purpose: To detect keratoconus using optical coherence tomography (OCT) corneal map parameters and patterns. Setting: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA DESIGN:: Cross-sectional observational study. Methods: A spectral-domain OCT was used to acquire corneal and epithelial thickness maps in normal, manifest keratoconic, subclinical keratoconic, and forme fruste keratoconic (FFK) eyes. A two-step decision tree was designed. An eye will be classified as keratoconus if both decision tree conditions are met: First, at least one of the four quantitative corneal thickness (minimum, minimum-maximum, superonasal-inferotemporal) and epithelial thickness (standard deviation) map parameters exceed cutoff values. Second, presence of ...

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    23. A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps

      A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps

      PURPOSE: To develop a coincident thinning (CTN) index to differentiate between keratoconic and healthy corneas using optical coherence tomography (OCT) measurements of pachymetry and epithelial thickness. METHODS: Pattern deviation maps of pachymetry and epithelial thickness were generated using Fourier-domain OCT images of the cornea. The co-localized thinning of the two maps was quantified using a novel CTN index, which was calculated from Gaussian fits of the regions of maximum relative thinning. The CTN index was validated using k-fold cross-validation, and its classification performance was compared to minimum pachymetry and maximum keratometry. RESULTS: A total of 82 normal eyes and 133 ...

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    1-24 of 264 1 2 3 4 ... 9 10 11 »
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