1. Koen A. Vermeer

    0 Comments Leave a Comment

    1-15 of 19 1 2 »
    1. Mentioned In 19 Articles

    2. Attenuation Coefficients from SD-OCT Data: Structural Information Beyond Morphology on RNFL Integrity in Glaucoma

      Attenuation Coefficients from SD-OCT Data: Structural Information Beyond Morphology on RNFL Integrity in Glaucoma
      Purpose: To explore the attenuation coefficient (AC) of the retinal nerve fiber layer (RNFL) in spectral domain optical coherence tomography (OCT) images, in healthy eyes and eyes affected by glaucoma. To assess the relation between RNLF AC, disease severity, RNFL thickness, visual field sensitivity threshold, spatial location and age. Patients and Methods: We analyzed peripapillary circle scans of a clinical OCT device (Spectralis OCT, Heidelberg Engineering, Heidelberg, Germany) in 102 ...
      Read Full Article
    3. Joint Segmentation of Retinal Layers and Focal Lesions in 3-D OCT Data of Topologically Disrupted Retinas

      Joint Segmentation of Retinal Layers and Focal Lesions in 3-D OCT Data of Topologically Disrupted Retinas
      Accurate quantification of retinal structures in 3-D optical coherence tomography data of eyes with pathologies provides clinically relevant information. We present an approach to jointly segment retinal layers and lesions in eyes with topology-disrupting retinal diseases by a loosely coupled level set framework. In the new approach, lesions are modeled as an additional space-variant layer delineated by auxiliary interfaces. Furthermore, the segmentation of interfaces is steered by local differences in ...
      Read Full Article
    4. Automatic estimation of retinal nerve fiber bundle orientation in SD-OCT images using a structure-oriented smoothing filter

      Automatic estimation of retinal nerve fiber bundle orientation in SD-OCT images using a structure-oriented smoothing filter
      Optical coherence tomography (OCT) yields high-resolution, three-dimensional images of the retina. A better understanding of retinal nerve fiber bundle (RNFB) trajectories in combination with visual field data may be used for future diagnosis and monitoring of glaucoma. However, manual tracing of these bundles is a tedious task. In this work, we present an automatic technique to estimate the orientation of RNFBs from volumetric OCT scans. Our method consists of several ...
      Read Full Article
    5. Loosely coupled level sets for simultaneous 3D retinal layer segmentation in optical coherence tomography

      Loosely coupled level sets for simultaneous 3D retinal layer segmentation in optical coherence tomography
      Optical coherence tomography (OCT) yields high-resolution, three-dimensional images of the retina. Reliable segmentation of the retinal layers is necessary for the extraction of clinically useful information. We present a novel segmentation method that operates on attenuation coefficients and incorporates anatomical knowledge about the retina. The attenuation coefficients are derived from in-vivo human retinal OCT data and represent an optical property of the tissue. Then, the layers in the retina are ...
      Read Full Article
    6. Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

      Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions
      In polarization-sensitive optical coherence tomography (PS-OCT) the use of single-mode fibers causes unpredictable polarization distortions which can result in increased noise levels and erroneous changes in calculated polarization parameters. In the current paper this problem is addressed by a new Jones matrix analysis method that measures and corrects system polarization distortions as a function of wavenumber by spectral analysis of the sample surface polarization state and deeper located birefringent tissue ...
      Read Full Article
    7. Systems, methods and computer-readable medium for determining depth-resolved physical and/or optical properties of scattering media by analyzing measured data over a range of depths

      Systems, methods and computer-readable medium for determining depth-resolved physical and/or optical properties of scattering media by analyzing measured data over a range of depths
      In depth-resolved imaging of scattering media, incident light interacts with tissue in a complex way before the signal reaches the detector: Light interacts with media between the light source and a specific depth, then scatters at that depth and the backscattered light again interacts with media on its way to the detector. The resulting depth-resolved signal therefore likely does not directly represent a physical or optical property of the media ...
      Read Full Article
    8. Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans

      Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans
      In conventional phase-resolved OCT blood flow is detected from phase changes between successive A-scans. Especially in high-speed OCT systems this results in a short evaluation time interval. This method is therefore often unable to visualize complete vascular networks since low flow velocities cause insufficient phase changes. This problem was solved by comparing B-scans instead of successive A-scans to enlarge the time interval. In this paper a detailed phase-noise analysis of ...
      Read Full Article
    9. Fully-funded medical image analysis PhD student position: Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases

      Fully-funded medical image analysis PhD student position: Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases
      ...d a sample of a written report in English, should be sent to Koen Vermeer (k.vermeer@eyehospital.nl). For more information about this position, please contact Koen Vermeer by e-mail or by phone (+31-650503833)....
      Read Full Article
    10. Fully-funded biomedical optics PhD student position: Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases

      Fully-funded biomedical optics PhD student position: Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases
      Project description Current clinical ophthalmic practice focuses on assessing the (chorio)retinal condition based on various imaging techniques that are incapable of quantitatively determining the state of the retina. In this project, we will develop techniques to quantitatively assess various optical properties of the retina and its separate layers, thereby providing information about the health status of the retina. These properties are the attenuation coefficient, polarization properties and the spectral ...
      Read Full Article
    11. Challenges in estimating the accuracy of imaging-based detection methods for glaucomatous progression

      Challenges in estimating the accuracy of imaging-based detection methods for glaucomatous progression
      The accuracy of glaucoma diagnosis by imaging devices that are commonly used in clinical practice, such as the GDx, the Heidelberg retinal tomograph and optical coherence tomography (OCT) is at a very high level, often surpassing the accuracy of trained ophthalmologists. 1 Because glaucoma specialists are considered to be the gold standard that imaging devices are tested against, the interobserver and intraobserver agreement of these specialists impose a limit on ...
      Read Full Article
      Mentions: Koen A. Vermeer
    12. Real-time eye motion correction in phase-resolved OCT angiography with tracking SLO

      Real-time eye motion correction in phase-resolved OCT angiography with tracking SLO
      In phase-resolved OCT angiography blood flow is detected from phase changes in between A-scans that are obtained from the same location. In ophthalmology, this technique is vulnerable to eye motion. We address this problem by combining inter-B-scan phase-resolved OCT angiography with real-time eye tracking. A tracking scanning laser ophthalmoscope (TSLO) at 840 nm provided eye tracking functionality and was combined with a phase-stabilized optical frequency domain imaging (OFDI) system at ...
      Read Full Article
    13. RPE-normalized RNFL attenuation coefficient maps derived from volumetric OCT imaging for glaucoma

      RPE-normalized RNFL attenuation coefficient maps derived from volumetric OCT imaging for glaucoma
      Purpose: We present spatial retinal nerve fiber layer (RNFL) attenuation coefficient maps for healthy and glaucomatous eyes based on optical coherence tomography (OCT) measurements. Quantitative analyses of differences between healthy and glaucomatous eyes were performed. Methods: Peripapillary volumetric images of 10 healthy and 8 glaucomatous eyes were acquired by a Spectralis OCT system (Heidelberg Engineering, Germany). Per A-line, the RNFL's attenuation coefficient was determined based on a method that ...
      Read Full Article
    14. The Effect of Glaucoma on the Optical Attenuation Coefficient of the Retinal Nerve Fiber Layer in Spectral Domain Optical Coherence Tomography Images

      The Effect of Glaucoma on the Optical Attenuation Coefficient of the Retinal Nerve Fiber Layer in Spectral Domain Optical Coherence Tomography Images
      Purpose: To demonstrate the effect of glaucoma on the optical attenuation coefficient of the retinal nerve fiber layer (RNFL) in Spectral Domain Optical Coherence Tomography (SD-OCT) images. Methods: We analyzed images of the peripapillary areas in 10 healthy and 30 glaucomatous eyes (mild, moderate and advanced glaucoma, 10 eyes each), scanned with the Spectralis OCT (Heidelberg Engineering GmbH, Dossenheim, Germany). To calculate the RNFL attenuation coefficient (µatt), determined by the ...
      Read Full Article
    15. 1-15 of 19 1 2 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. About Koen A. Vermeer

    Koen A. Vermeer is with the Rotterdam Ophthalmic Institute, The Netherlands.