1. Articles from alexander c. walsh

    1-24 of 36 1 2 »
    1. Error Correction and Quantitative Subanalysis of Optical Coherence Tomography Data Using Computer-Assisted Grading

      Error Correction and Quantitative Subanalysis of Optical Coherence Tomography Data Using Computer-Assisted Grading

      purpose. To demonstrate feature subanalysis and error correction of optical coherence tomography (OCT) data by using computer-assisted grading. methods. The raw exported StratusOCT (Carl Zeiss Meditec, Inc., Dublin, CA) scan data from 20 eyes of 20 patients were analyzed using custom software (termed OCTOR) designed to allow the user to define manually the retinal borders on each radial line scan. Measurements calculated by the software, including thickness of the nine standard macular subfields, foveal center point (FCP), and macular volume, were compared between two graders and with the automated Stratus analysis. Mean and range of differences for each parameter were ...

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    2. Errors in Retinal Thickness Measurements Obtained by Optical Coherence Tomography

      Errors in Retinal Thickness Measurements Obtained by Optical Coherence Tomography

      Objective To report the frequency and severity of optical coherence tomography (OCT) retinal thickness measurement errors and to describe parameters that predict these errors. Design Observational case series. Participants Two hundred consecutive patients undergoing OCT imaging. Methods One eye (primary) from each of 200 consecutive patients undergoing Stratus OCT imaging (Carl Zeiss Meditec, Dublin, CA) with radial lines or fast macular thickness-based acquisition protocols was selected for review by 2 graders. On each of the line scans, graders evaluated the position of the automated retinal boundary lines (inner retinal surface and retinal pigment epithelium band) used by the OCT machine ...

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    3. Inflatable medical interfaces and other medical devices, systems, and methods

      Inflatable medical interfaces and other medical devices, systems, and methods

      An inflatable mask with two ocular cavities can seal against a user's face by forming an air-tight seal around the periphery of the user's eye socket. The sealed air-tight ocular cavity can be pressurized to take ocular measurements. The mask can conform to the contours of a user's face by inflating or deflating the mask. In addition, the distance between the user and a medical device (e.g. an optical coherence tomography instrument) can be adjusted by inflating or deflating the mask. Also disclosed herein is an electronic encounter portal and an automated eye examination. Other embodiments ...

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    4. Inflatable Medical Interfaces And Other Medical Devices, Systems, And Methods

      Inflatable Medical Interfaces And Other Medical Devices, Systems, And Methods

      An inflatable mask with two ocular cavities can seal against a user's face by forming an air-tight seal around the periphery of the user's eye socket. The sealed air-tight ocular cavity can be pressurized to take ocular measurements. The mask can conform to the contours of a user's face by inflating or deflating the mask. In addition, the distance between the user and a medical device (e.g. an optical coherence tomography instrument) can be adjusted by inflating or deflating the mask. Also disclosed herein is an electronic encounter portal and an automated eye examination. Other embodiments ...

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    5. Atypical Outer Retinal Fluid Accumulation in Choroidal Neovascularization: A Novel OCT Finding

      Atypical Outer Retinal Fluid Accumulation in Choroidal Neovascularization: A Novel OCT Finding

      BACKGROUND AND OBJECTIVE: To report a novel optical coherence tomography (OCT) finding in choroidal neovascularization (CNV). PATIENTS AND METHODS: The authors identified seven eyes with CNV demonstrating the atypical pattern of fluid accumulation within the outer retina on OCT. Patient demographics, best corrected visual acuity and spectral-domain OCT (SD-OCT) images were collected for all available follow-up visits. Volume and area of the fluid were measured on SD-OCT. Microperimetry was performed in one case. RESULTS: The outer retinal fluid was located between the external limiting membrane (ELM) and the outer photoreceptor band on SD-OCT. Within this area, the outer segments of ...

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    6. The Retinal Disease Screening Study: Retrospective Comparison of Nonmydriatic Fundus Photography and Three-Dimensional Optical Coherence Tomography for Detection of Retinal Irregularities

      The Retinal Disease Screening Study: Retrospective Comparison of Nonmydriatic Fundus Photography and Three-Dimensional Optical Coherence Tomography for Detection of Retinal Irregularities

      Purpose. To determine the sensitivity of three-dimensional optical coherence tomography (3D-OCT) versus single field nonmydriatic fundus photography (FP) for detection of a variety of retinal abnormalities. Methods. Images from consecutive patients in a retina clinic undergoing simultaneous 3D-OCT (512×128) and single, foveal nonmydriatic 45° color fundus imaging with 3D-OCT-1000 in a 4 month-period were retrospectively collected. Findings from each modality were graded independently by two graders as present, questionable, or absent. Irregularities were separated into three categories for intermodality comparisons: epiretinal, retinal/subretinal, and RPE/choroidal irregularities. The approximate location of findings in relation to the 3D-OCT field was ...

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    7. Optical Coherence Tomography Device, Method, And System

      Optical Coherence Tomography Device, Method, And System

      In accordance with one aspect of the present invention, an optical coherence tomography instrument comprises an eyepiece for receiving at least one eye of a user is provided; a light source that outputs light that is directed through the eyepiece into the user's eye; an interferometer configured to produce optical interference using light reflected from the user's eye; an optical detector disposed so as to detect said optical interference; and electronics coupled to the detector. The electronics can be configured to perform a risk assessment analysis based on optical coherence tomography measurements obtained using the interferometer. An output ...

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    8. Comparison of Non-Mydriatic Fundus Photography and Three Dimensional Optical Coherence Tomography for Detection of Retinal Irregularities

      Comparison of Non-Mydriatic Fundus Photography and Three Dimensional Optical Coherence Tomography for Detection of Retinal Irregularities

      Purpose:To determine the sensitivity of detection for retinal abnormalities using 3D-OCT versus single field fundus imaging. Methods:Images from consecutive patients in a retina clinic undergoing simultaneous 3D-OCT (512x128) and single, foveal non-mydriatic 45 degree color fundus imaging with 3D-OCT-1000 (Topcon Corp, Tokyo, Japan) in a 4 months period were retrospectively collected. Findings for each modality were graded independently by two graders as present, questionable or absent. Findings were separated into 3 categories for intermodality comparisons: epiretinal, retinal/subretinal, and RPE/choroidal. The approximate location of findings in relation to the 3D-OCT field was noted as infield and out ...

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    9. Different phenotypes of the appearance of the outer plexiform layer on optical coherence tomography

      Different phenotypes of the appearance of the outer plexiform layer on optical coherence tomography

      Purpose To present a selected case series of different phenotypes of the normal outer plexiform layer (OPL) visualized by optical coherence tomography (OCT). Methods Five cases were selected to represent the spectrum of appearances of the OPL in this case series. Categorical descriptions of each manifestation were then developed. Additional SD-OCT scans were obtained from a normal volunteer to further support the hypothesis. Results The inner one-third of the OPL typically appears hyperreflective on OCT, while the outer two-thirds (Henle fiber layer) may have a more varied appearance. Six different phenotypes of Henle fiber layer reflectivity were noted in this ...

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    10. Evaluation of the Axial Location of Cystoid Spaces in Retinal Vein Occlusion Using Optical Coherence Tomography

      Evaluation of the Axial Location of Cystoid Spaces in Retinal Vein Occlusion Using Optical Coherence Tomography

      Purpose: To analyze the axial distribution of intraretinal cystoid changes in patients with retinal vein occlusion (RVO), incorporating a new hypothesis about the optical coherence tomographic boundary between the outer nuclear layer and the outer plexiform layer. Methods: Data were collected from patients with RVO who underwent spectral domain coherence tomography imaging. For each image set, certified graders evaluated each retinal layer for cystoid macular edema, defined as hyporeflective intraretinal cystoid spaces. Subretinal fluid, if present, was also noted. Results: Forty-eight eyes were evaluated (24 branch RVO, 18 central RVO, 6 hemiretinal vein occlusion). Cystoid macular edema was present in ...

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    11. The Retinal Disease Screening Study: Prospective Comparison of Nonmydriatic Fundus Photography and Optical Coherence Tomography for Detection of Retinal Irregularities

      The Retinal Disease Screening Study: Prospective Comparison of Nonmydriatic Fundus Photography and Optical Coherence Tomography for Detection of Retinal Irregularities

      Purpose. To compare the sensitivity of volume scanning with optical coherence tomography (OCT) to nonmydriatic color fundus photography (FP) for the detection of retinal irregularities in asymptomatic populations. Methods. Asymptomatic subjects without known ocular disease were recruited over a 6-month period. For each eye, two undilated 45° fundus images and four undilated volume OCT image sets covering the macula and optic nerve were obtained. Color images were evaluated for irregularities both inside and outside the area covered by OCT. OCT image sets were evaluated for internal limiting membrane irregularities, abnormal retinal thickness, hyper/hyporeflective features, and photoreceptor/retinal pigment epithelium ...

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    12. The Retinal Disease Screening Study: Prospective Comparison of Non-Mydriatic FP and Optical Coherence Tomography for Detection of Retinal Irregularities

      The Retinal Disease Screening Study: Prospective Comparison of Non-Mydriatic FP and Optical Coherence Tomography for Detection of Retinal Irregularities

      Purpose:To compare the sensitivity of volume scanning with optical coherence tomography (OCT), to non-mydriatic fundus photography, for the detection of retinal abnormalities in asymptomatic populations. Methods:Asymptomatic subjects without known ocular disease recruited over a six-month period .For each eye, two undilated 45º fundus images, and four undilated volume OCT image sets covering the macula and optic nerve, were obtained. Fundus photographs were evaluated for abnormalities both inside and outside the fundal area covered by OCT. OCT image sets were evaluated for internal limiting membrane irregularities, abnormal retinal thickness, hyper/hyporeflective foci, and photoreceptor/retinal pigment epithelium irregularities. Detection ...

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    13. Juxtapapillary Pigment Epithelium Detachment Observed in Asymptomatic Participants using Optical Coherence Tomograph

      Juxtapapillary Pigment Epithelium Detachment Observed in Asymptomatic Participants using Optical Coherence Tomograph

      Purpose. To use three-dimensional optical coherence tomography (3D-OCT) to assess the prevalence of juxtapapillary retinal pigment epithelial detachments (jPED) in an asymptomatic population. Methods. Asymptomatic participants (i.e. family members of patients) were prospectively recruited over a six-month period. Each subject completed a questionnaire prior to the acquisition of two undilated 45º fundus images and two undilated raster 3D-OCT scans (512x128) covering the macula and optic nerve from each eye using 3D-OCT-1000 (Topcon Co, Tokyo). Fundus images were graded for the presence of peripapillary atrophy (PPA), peripapillary pigment (PPP), drusen in the macula and drusen elsewhere; while 3D-OCT scans were ...

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    14. Optical coherence tomography device, method, and system

      Optical coherence tomography device, method, and system

      In accordance with one aspect of the present invention, an optical coherence tomography instrument comprises an eyepiece for receiving at least one eye of a user is provided; a light source that outputs light that is directed through the eyepiece into the user's eye; an interferometer configured to produce optical interference using light reflected from the user's eye; an optical detector disposed so as to detect said optical interference; and electronics coupled to the detector. The electronics can be configured to perform a risk assessment analysis based on optical coherence tomography measurements obtained using the interferometer. An output ...

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    15. Impact of scanning density on spectral domain optical coherence tomography assessments in neovascular age-related macular degeneration

      Impact of scanning density on spectral domain optical coherence tomography assessments in neovascular age-related macular degeneration

      Purpose:  To determine the effect of optical coherence tomography (OCT) B-scan density on the qualitative assessment of neovascular age-related macular degeneration (AMD). Methods:  Data were collected from 59 patients imaged with Topcon 3D OCT-1000 (128 B-scans × 512 A-scans). Custom software was used to generate less dense subsets of scans: 1/16 (eight B-scans), 1/8 (16 B-scans), 1/4 (32 B-scans) and 1/2 (64 B-scans). At each B-scan density, scans were assessed for cystoid spaces, subretinal fluid (SRF), subretinal tissue (SRT) and pigment epithelium detachment (PED). For each sampling density, sensitivity, specificity and predictive values were calculated using the ...

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    16. Assessment of Differential Pharmacodynamic Effects using Optical Coherence Tomography in Neovascular Age-Related Macular Degeneration

      Assessment of Differential Pharmacodynamic Effects using Optical Coherence Tomography in Neovascular Age-Related Macular Degeneration

      Purpose: To assess the differential pharmacodynamic effects of bevacizumab (Avastin), pegaptanib (Macugen), and verteporfin photodynamic therapy (PDT), using novel OCT parameters, in a recently completed phase III/IV clinical trial. Methods: Data from 122 patients participating in the Avastin (Bevacizumab) for Choroidal neovascularization (ABC) trial, were evaluated. Stratus OCT images were analyzed using custom software - changes in volume of the neurosensory retina, subretinal fluid (SRF), pigment epithelium detachment (PED), and subretinal tissue, were calculated over the 54-week trial period. Results: Reductions in retinal oedema were more than twice as great from bevacizumab than pegaptanib (-0.82 mm3 versus -0.31 ...

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    17. Clinical Significance of B-Scan Averaging With SD-OCT

      Clinical Significance of B-Scan Averaging With SD-OCT
      Averaging multiple scans is a potential advantage of optical coherence tomography. The authors evaluate the qualitative benefits of B-scan averaging on the visualization of outer retinal structures. A retrospective analysis was performed on Cirrus OCT (Carl Zeiss Meditec, Dublin, CA) B-scans from 1 eye of 35 patients referred to the imaging unit who underwent three types of scan acquisitions: no averaging, 4× averaging, and 20× averaging. Masked assessment of quality was made using a qualitative scale of 0 (worst) to 3 according to the ability to identify structure, brightness, and continuity. Quality scores consistently improved with 4× averaging, but improved ...
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    18. Simple Estimation of Clinically-Relevant Lesion Volumes using Spectral Domain-Optical Coherence Tomography in Neovascular Age-Related Macular Degeneration

      Simple Estimation of Clinically-Relevant Lesion Volumes using Spectral Domain-Optical Coherence Tomography in Neovascular Age-Related Macular Degeneration

      Purpose: To evaluate simple methods of estimating the volume of clinically-relevant features in neovascular age-related macular degeneration (NVAMD) using spectral domain OCT (SD-OCT). Methods: Using a database of NVAMD cases imaged with macular cube (512 x 128) SD-OCT scans from either a Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) or a 3D-OCT-1000 (Topcon, Inc., Tokyo, Japan), we retrospectively selected visits where CME, SRF or a PED were evident. Patients with single visits were analyzed in the cross-sectional analysis (CSA) and those with a baseline visit and 3 or more follow-up visits in the longitudinal analysis (LA). The volume of ...

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    19. Binocular Optical Coherence Tomography

      Binocular Optical Coherence Tomography
      The use of optical coherence tomography (OCT) in the field of ophthalmology has increased rapidly in recent years and may continue on this trajectory as more indications for OCT imaging are described. Recent pressures on the healthcare system, such as rising costs, increasing demand, and decreasing reimbursements, suggest that continued growth in OCT use may be unsustainable unless cheaper and more efficient methods are developed. Binocular OCT has the potential to decrease the cost, increase the quality, and improve the efficiency not just of OCT imaging, but of eye care as a whole. Binocular OCT devices should be cheaper to ...
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    20. Spatial Distribution of Posterior Pole Choroidal Thickness by Spectral Domain Optical Coherence Tomography

      Spatial Distribution of Posterior Pole Choroidal Thickness by Spectral Domain Optical Coherence Tomography
      Purpose: To study the spatial distribution of posterior pole choroidal thickness (CT) in healthy eyes using spectral domain optical coherence tomography (OCT). Methods: Fifty-nine eyes from 30 subjects with no retinal or choroidal disease were examined with the Cirrus HD-OCT (Carl Zeiss Meditec) using macular volume cube scanning protocols. A randomly chosen-subset also had multi-field analysis performed (volume scans centered on and surrounding the optic nerve head (ONH)). CT was manually quantified using a validated reading center tool (“3D-OCTOR”). For macular scans, mean CT was calculated for each Early Treatment Diabetic Retinopathy Study (ETDRS) subfield. Compound “posterior pole” CT maps ...
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    21. Comparison of manually corrected retinal thickness measurements from multiple spectral-domain optical coherence tomography instruments

      Comparison of manually corrected retinal thickness measurements from multiple spectral-domain optical coherence tomography instruments

      Background/aims To compare retinal thickness measurements from three different spectral domain optical coherence instruments when manual segmentation is employed to standardise retinal boundary locations. Methods 40 eyes of 21 healthy subjects were scanned on the Cirrus HD-OCT, Topcon 3D-OCT-2000 and Heidelberg Spectralis-OCT. Raw data were imported into custom grading software (3D-OCTOR). Manual segmentation was performed on every data set, and retinal thickness values in the foveal central subfield were computed. Results 37 eyes of 20 subjects were gradable on every machine. The average retinal thicknesses for these eyes were 236.7 µm (SD 20.1), 235.7 µm (SD ...

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    22. Relationship between Optical Coherence Tomography Retinal Parameters and Visual Acuity in Diabetic Macular Edema

      Relationship between Optical Coherence Tomography Retinal Parameters and Visual Acuity in Diabetic Macular Edema

      Purpose: To investigate the relationship between optical coherence tomography (OCT)-derived measurements of retinal morphology and visual acuity in patients with diabetic macular edema.Design: Retrospective cross-sectional study.Participants: A total of 67 consecutive patients (67 eyes) with diabetic macular edema (DME) who underwent Stratus OCT imaging (Carl Zeiss Meditec, Inc., Dublin, CA).Methods: Best-corrected Snellen visual acuity was recorded for each patient. Raw exported Stratus OCT images for each patient were analyzed using custom software entitled “OCTOR,” which allows the precise positioning of prespecified boundaries on individual B-scans. Thickness, volume, and intensity were calculated for neurosensory retina and subretinal ...

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    23. Detection of Cystoid Macular Edema with Three-Dimensional Optical Coherence Tomography versus Fluorescein Angiography

      Purpose: To compare the sensitivity and reproducibility of three-dimensional optical coherence tomography (3D-OCT) and fluorescein angiography (FA) for the detection of cystoid macular edema (CME). Methods: Data from all patients who underwent digital FA (Topcon 50IX, Topcon Corp.) and 512x128 horizontal raster 3D-OCT scans (3D-OCT-1000, Topcon Corp.) on the same day in a retina subspecialty clinic were retrospectively collected. Images were reviewed independently by four reading center graders and adjudicated as a group to render a single result for each eye and each imaging modality. Kappa statistics were used to determine the level of agreement between graders for each modality ...

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    24. Optical Coherence Tomography Device, Method, And System (Wo 2010/009450)

      Optical Coherence Tomography Device, Method, And System (Wo 2010/009450)
      In accordance with one aspect of the present invention, an optical coherence tomography-based ophthalmic testing center system includes an optical coherence tomography instrument comprising an eyepiece for receiving at least one eye of a user or subject; a light source that outputs light that is directed through the eyepiece into the user's or subject's eye, an interferometer configured to produce optical interference using light reflected from the user's/subject's eye, an optical detector disposed so as to detect said optical interference; and a processing unit coupled to the detector. The ophthalmic testing center system can be ...
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