1. Articles from Jonathan Liu

    1-13 of 13
    1. Characterization of Choroidal Layers in Normal Aging Eyes Using Enface Swept-Source Optical Coherence Tomography

      Characterization of Choroidal Layers in Normal Aging Eyes Using Enface Swept-Source Optical Coherence Tomography

      Purpose To characterize qualitative and quantitative features of the choroid in normal eyes using enface swept-source optical coherence tomography (SS-OCT). Methods Fifty-two eyes of 26 consecutive normal subjects were prospectively recruited to obtain multiple three-dimensional 12x12mm volumetric scans using a long-wavelength high-speed SS-OCT prototype. A motion-correction algorithm merged multiple SS-OCT volumes to improve signal. Retinal pigment epithelium (RPE) was segmented as the reference and enface images were extracted at varying depths every 4.13μm intervals. Systematic analysis of the choroid at different depths was performed to qualitatively assess the morphology of the choroid and quantify the absolute thicknesses as ...

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    2. Systems Engineer Position Opening at Topcon Medical Systems in Oakland, New Jersey

      Systems Engineer Position Opening at Topcon Medical Systems in Oakland, New Jersey

      An exciting opportunity for a highly motivated system engineer to work creatively within a dedicated R&D laboratory (Topcon Advanced Biomedical Imaging Laboratory, Oakland, NJ) contributing to interdisciplinary projects with global impact. Primary responsibilities include system development for ophthalmic imaging devices, supporting both prototype and commercial system development efforts. The position requires diverse engineering and programming experience including system integration, data acquisition and test equipment control, signal and image processing, and image analysis algorithm development. While this position has an emphasis on system development, the successful candidate is also expected to participate in advanced ophthalmic imaging techniques and imaging analysis ...

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    3. Cardiac-Gated En Face Doppler Measurement of Retinal Blood Flow Using Swept Source Optical Coherence Tomography at 100,000 Axial Scans per Second

      Cardiac-Gated En Face Doppler Measurement of Retinal Blood Flow Using Swept Source Optical Coherence Tomography at 100,000 Axial Scans per Second

      Purpose: To develop and demonstrate a cardiac gating method for repeatable in vivo measurement of total retinal blood flow (TRBF) in humans using en face Doppler optical coherence tomography (OCT) at commercially available imaging speeds. Methods: A prototype swept-source OCT system operating at 100 kHz axial scan rate was developed and interfaced with a pulse oximeter. Using the plethysmogram measured from the earlobe, Doppler OCT imaging of a 1.5 mm×2 mm area at the optic disc at 1.8 volumes/sec was synchronized to cardiac cycle to improve sampling of pulsatile blood flow. Post-processing algorithms were developed to ...

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    4. AGREEMENT AND REPRODUCIBILITY OF RETINAL PIGMENT EPITHELIAL DETACHMENT VOLUMETRIC MEASUREMENTS THROUGH OPTICAL COHERENCE TOMOGRAPHY

      AGREEMENT AND REPRODUCIBILITY OF RETINAL PIGMENT EPITHELIAL DETACHMENT VOLUMETRIC MEASUREMENTS THROUGH OPTICAL COHERENCE TOMOGRAPHY

      Purpose: To assess the agreement and reproducibility of retinal pigment epithelial detachment (RPED) volumetric measurements using a commercially available optical coherence tomography software available for the Zeiss Cirrus HD-OCT. Methods: Twelve eyes of 10 patients with a diagnosis of neovascular age-related macular degeneration with RPED, seen at the New England Eye Center between October 2012 and December 2012, were enrolled in the study. Three separate scans per affected eye were obtained using the "Macular Cube 512 x 128" protocol. "Retinal pigment epithelial (RPE) elevation analysis" software was used to measure RPED volumes in the central 3-mm and 5-mm circles by ...

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    5. Depth-encoded all-fiber swept source polarization sensitive OCT

      Depth-encoded all-fiber swept source polarization sensitive OCT

      Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of conventional OCT and can assess depth-resolved tissue birefringence in addition to intensity. Most existing PS-OCT systems are relatively complex and their clinical translation remains difficult. We present a simple and robust all-fiber PS-OCT system based on swept source technology and polarization depth-encoding. Polarization multiplexing was achieved using a polarization maintaining fiber. Polarization sensitive signals were detected using fiber based polarization beam splitters and polarization controllers were used to remove the polarization ambiguity. A simplified post-processing algorithm was proposed for speckle noise reduction relaxing the demand for phase stability. We ...

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    6. In-Vivo Lamina Cribrosa Microarchitecture in Healthy and Glaucomatous Eyes as Assessed by Optical Coherence Tomography

      In-Vivo Lamina Cribrosa Microarchitecture in Healthy and Glaucomatous Eyes as Assessed by Optical Coherence Tomography

      Purpose: Lamina cribrosa (LC) is a leading location of glaucomatous damage. The purpose of this study is to compare LC 3-dimensional microarchitecture between healthy and glaucomatous eyes in-vivo using optical coherence tomography (OCT). Methods: Sixty-eight eyes (19 healthy and 49 glaucomatous) from 47 subjects were scanned in a 3.5x3.5x3.64mm volume (400x400x896 pixels) at the optic nerve head using swept-source OCT. The LC microarchitecture parameters were measured on the visible LC by an automated segmentation algorithm. The LC parameters were compared to diagnosis and visual field mean deviation (MD) using a linear mixed effects model accounting for age ...

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    7. Documentation of Intraretinal Retinal Pigment Epithelium Migration via High-Speed Ultrahigh-Resolution Optical Coherence Tomography

      Documentation of Intraretinal Retinal Pigment Epithelium Migration via High-Speed Ultrahigh-Resolution Optical Coherence Tomography

      Purpose: To describe the features of intraretinal retinal pigment epithelium (RPE) migration documented on a prototype spectral-domain, high-speed, ultrahigh-resolution optical coherence tomography (OCT) device in a group of patients with early to intermediate dry age-related macular degeneration (AMD) and to correlate intraretinal RPE migration on OCT to RPE pigment clumping on fundus photographs. Design: Retrospective, noncomparative, noninterventional case series. Participants: Fifty-five eyes of 44 patients seen at the New England Eye Center between December 2007 and June 2008 with early to intermediate dry AMD. Methods: Three-dimensional OCT scan sets from all patients were analyzed for the presence of intraretinal RPE ...

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    8. Ultrahigh-speed volumetric ophthalmic OCT imaging at 800nm and 1050nm

      Ultrahigh-speed volumetric ophthalmic OCT imaging at 800nm and 1050nm
      The performance and imaging characteristics of ultrahigh speed ophthalmic optical coherence tomography (OCT) are investigated. In vivo imaging results are obtained at 850nm and 1050nm using different configurations of spectral and swept source / Fourier domain OCT. A spectral / Fourier domain instrument using a high speed CMOS linescan camera with SLD light source centered at 850nm achieves speeds of ~91,000 axial scans per second with ~3µm axial resolution in tissue. A spectral / Fourier domain instrument using an InGaAs linescan camera with SLD light source centered at 1050nm achieves ~47,000 axial scans per second with ~7µm resolution in tissue. A ...
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    9. Clinical Assessment of Mirror Artifacts in Spectral Domain Optical Coherence Tomography

      Clinical Assessment of Mirror Artifacts in Spectral Domain Optical Coherence Tomography
      Purpose: To investigate the characteristics of a spectral domain Optical Coherence Tomography (SD OCT) image artifact known as the "mirror artifact", calculate its prevalence, analyze potential risk factors, measure severity, and correlate it to spherical equivalent and central visual acuity (VA). Methods: Cirrus HD-OCT Macular Cube 512x128 scans taken between January 2008 and February 2009 at the New England Eye Center were analyzed for the presence of mirror artifacts. Artifact severity was analyzed by the degree of segmentation breakdown that it causes on the macular map. A retrospective medical records review was conducted for patients with artifacts and for a ...
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    10. Ultrahigh speed spectral/Fourier domain OCT imaging in ophthalmology

      Ultrahigh speed Spectral/Fourier domain ophthalmic OCT imaging at 70,000-312,500 axial scans per second is demonstrated using a high speed CMOS camera at 800 nm. Comparative imaging results of the fovea illustrate the performance tradeoffs between different imaging speeds and spectrometer configurations. Dense 3D volumetric acquisitions show minimal motion artifacts when acquired at 250,000 axial scans per second. The porous structure of the lamina cribrosa is shown in en face images extracted from a dense volumetric acquisition of the optical nerve head acquired at 106, 382 axial scans per second. Rapid repeated volume imaging (4D-OCT) shows blood ...
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    11. Assessment of Artifacts and Reproducibility across Spectral- and Time-Domain Optical Coherence Tomography Devices

      Purpose: To report the frequency of optical coherence tomography (OCT) scan artifacts and to compare macular thickness measurements, interscan reproducibility, and interdevice agreeability across 3 spectral-domain (SD) OCT (also known as Fourier domain; Cirrus HD-OCT, RTVue-100, and Topcon 3D-OCT 1000) devices and 1 time-domain (TD) OCT (Stratus OCT) device.Design: Prospective, noncomparative, noninterventional case series.Participants: Fifty-two patients seen at the New England Eye Center, Tufts Medical Center Retina Service, between February and August 2008.Methods: Two scans were performed for each of the SD OCT protocols: Cirrus macular cube 512×128 (software version 3.0; Carl Zeiss Meditec, Inc ...
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    12. Three-dimensional ultrahigh resolution optical coherence tomography imaging of age-related macular degeneration

      Three-dimensional ultrahigh resolution optical coherence tomography imaging of age-related macular degeneration

      Ultrahigh resolution optical coherence tomography (OCT) enhances the ability to visualize different intra retinal layers. In age-related macular degeneration (AMD), pathological changes in individual retinal layers, including photoreceptor inner and outer segments and retinal pigment ... [Opt. Express 17, 4046-4060 (2009)]

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    13. Ultrahigh speed spectral/Fourier domain ophthalmic OCT imaging

      Ultrahigh speed spectral / Fourier domain optical coherence tomography (OCT) imaging using a CMOS line scan camera with acquisition rates of 70,000 - 312,500 axial scans per second is investigated. Several design configurations are presented to illustrate trade-offs between acquisition speed, sensit ... [Proc. SPIE 7163, 716307 (2009)] published Wed Feb 18, 2009.
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    1-13 of 13
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  2. Topics in the News

    1. (12 articles) Massachusetts Institute of Technology
    2. (12 articles) James G. Fujimoto
    3. (10 articles) Tufts University
    4. (10 articles) Jay S. Duker
    5. (9 articles) Jonathan J. Liu
    6. (6 articles) University of Pittsburgh
    7. (6 articles) Yueli L. Chen
    8. (6 articles) Joel S. Schuman
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    Three-dimensional ultrahigh resolution optical coherence tomography imaging of age-related macular degeneration Clinical Assessment of Mirror Artifacts in Spectral Domain Optical Coherence Tomography Ultrahigh-speed volumetric ophthalmic OCT imaging at 800nm and 1050nm Documentation of Intraretinal Retinal Pigment Epithelium Migration via High-Speed Ultrahigh-Resolution Optical Coherence Tomography In-Vivo Lamina Cribrosa Microarchitecture in Healthy and Glaucomatous Eyes as Assessed by Optical Coherence Tomography Depth-encoded all-fiber swept source polarization sensitive OCT Systems Engineer Position Opening at Topcon Medical Systems in Oakland, New Jersey Direct inverse linearization of piezoelectric actuator’s initial loading curve and its applications in full-field optical coherence tomography (FF-OCT) Peripapillary Retinal and Choroidal Perfusion in Nonarteritic Ischemic Optic Neuropathy Using Optical Coherence Tomography Angiography Reliability of foveal avascular zone measurements in eyes with retinal vein occlusion using optical coherence tomography angiography SD-OCT parameters and visual field defect in chiasmal compression and the diagnostic value of neural network model Visualization of deep choroidal vasculatures and measurement of choroidal vascular density: a swept-source optical coherence tomography angiography approach