1. Articles from Murray Johnstone

    1-12 of 12
    1. Aqueous outflow regulation: Optical coherence tomography (OCT) imaging implicates pressure-dependent tissue motion

      Aqueous outflow regulation: Optical coherence tomography (OCT) imaging implicates pressure-dependent tissue motion

      Glaucoma is a leading cause of blindness worldwide and results from damage to the optic nerve. Currently, intraocular pressure is the only treatable risk factor. Changes in aqueous outflow regulate pressure; regulation becomes abnormal in glaucoma. From inside the eye aqueous flows out through the trabecular meshwork into a venous sinus called Schlemm's canal, next into collector channels and finally returns to the episcleral vessels of the venous system. The location of aqueous outflow regulation is unknown. Ex vivo and in vivo studies implicate both pressure-dependent trabecular tissue motion and tissues distal to Schlemm's canal in regulation of ...

      Read Full Article
    2. Wide-field optical coherence tomography based microangiography for retinal imaging

      Wide-field optical coherence tomography based microangiography for retinal imaging

      Optical coherence tomography angiography (OCTA) allows for the evaluation of functional retinal vascular networks without a need for contrast dyes. For sophisticated monitoring and diagnosis of retinal diseases, OCTA capable of providing wide-field and high definition images of retinal vasculature in a single image is desirable. We report OCTA with motion tracking through an auxiliary real-time line scan ophthalmoscope that is clinically feasible to image functional retinal vasculature in patients, with a coverage of more than 60 degrees of retina while still maintaining high definition and resolution. We demonstrate six illustrative cases with unprecedented details of vascular involvement in retinal ...

      Read Full Article
    3. Pulsatile motion of trabecular meshwork in a patient with iris cyst by phase-sensitive optical coherence tomography: a case report

      Pulsatile motion of trabecular meshwork in a patient with iris cyst by phase-sensitive optical coherence tomography: a case report

      45-year-old man was diagnosed with a 3 mm × 3 mm iris cyst located at 9 o’clock behind iris and protruding into temporal angle by slit lamp examination, gonioscopy, and ultrasound biomicroscopy (UBM). Phase-sensitive optical coherence tomography (PhS-OCT) was applied on this case for the quantitative measurements of trabecular meshwork (TM) motion. The frequency of TM motion was with the same rhythm of the patient’s peripheral pulse. Its amplitude on the closed angle region showed significant smaller than the open angle region. PhS-OCT can be a useful tool for the diagnosis and follow-up in ocular diseases surrounding iridocorneal angle.

      Read Full Article
    4. Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the ...

      Read Full Article
    5. Full anterior segment biometry with extended imaging range spectral domain optical coherence tomography at 1340 nm

      Full anterior segment biometry with extended imaging range spectral domain optical coherence tomography at 1340 nm

      We demonstrate an extended-imaging-range anterior-segment optical coherence tomography (eAS-OCT) system for the biometric assessment of full AS in human eye. This newly developed eAS-OCT operating at 1340-nm wavelength band is simultaneously capable of an imaging speed of 120 kHz A-line scan rate, an axial resolution of 7.2 μ m, and an extended imaging range of up to 16 mm in air. Imaging results from three healthy subjects and one subject with a narrow-angle demonstrate the instrument’s utility. With this system, it can provide anatomical dimensions of AS, including central corneal thickness, anterior chamber width, anterior chamber depth, crystalline lens ...

      Read Full Article
    6. Pulsatile motion of the trabecular meshwork in healthy human subjects quantified by phase-sensitive optical coherence tomography

      Pulsatile motion of the trabecular meshwork in healthy human subjects quantified by phase-sensitive optical coherence tomography

      Aqueous leaves the anterior chamber of eye by passing through the trabecular meshwork (TM), a tissue thought to be responsible for increased outflow resistance in glaucoma. Motion assessment could permit characterization of TM biomechanical properties necessary to maintain intra-ocular pressure (IOP) within a narrow homeostatic range. In this paper, we report the first in vivo identification of TM motion in humans. We use a phase-sensitive optical coherence tomography (PhS-OCT) system with sub-nanometer sensitivity to detect and image dynamic pulse-induced TM motion. To permit quantification of TM motion and relationships we develop and apply a phase compensation algorithm permitting removal of ...

      Read Full Article
    7. Noninvasive imaging of pulsatile movements of the optic nerve head in normal human subjects using phase-sensitive spectral domain optical coherence tomography

      Noninvasive imaging of pulsatile movements of the optic nerve head in normal human subjects using phase-sensitive spectral domain optical coherence tomography

      We report use of high-speed spectral domain optical coherence tomography to noninvasively image pulsatile axial movement of the optic nerve head (ONH) in normal human subjects. Time-lapse B-scan mode is used to image the ONH at 500 frames per second. Capture of phase differences between adjacent B-scans permits extraction of axial ONH movement. We find the ONH experiences continuous oscillatory axial motion that is strongly correlated with simultaneously measured pulsatile blood flow in the central retinal artery.

      Read Full Article
    8. Methods And Systems For Imaging Tissue Motion Using Optical Coherence Tomography

      Methods And Systems For Imaging Tissue Motion Using Optical Coherence Tomography

      A system and method for measuring tissue motion within a living tissue of the anterior segment and aqueous outflow system of the eye in a subject are provided. Tissue movements are extracted from a plurality of images acquired from the living tissue using an optical coherence tomography system. The images may be corrected using motion compensation. To extract the tissue movements from the images, waves from a cardiac pulse or other externally induced pulses from the subject are acquired, and a pulse wave is defined for a given time, which is then correlated with a velocity wave defined for a ...

      Read Full Article
    9. Extended imaging depth to 12 mm for 1050-nm spectral domain optical coherence tomography for imaging the whole anterior segment of the human eye at 120-kHz A-scan rate

      Extended imaging depth to 12 mm for 1050-nm spectral domain optical coherence tomography for imaging the whole anterior segment of the human eye at 120-kHz A-scan rate

      We demonstrate a 1050-nm spectral domain optical coherence tomography (OCT) system with a 12 mm imaging depth in air, a 120 kHz A-scan rate and a 10 μm axial resolution for anterior-segment imaging of human eye, in which a new prototype InGaAs linescan camera with 2048 active-pixel photodiodes is employed to record OCT spectral interferograms in parallel. Combined with the full-range complex technique, we show that the system delivers comparable imaging performance to that of a swept-source OCT with similar system specifications.

      Read Full Article
    10. Optical microangiography provides correlation between microstructure and microvasculature of optic nerve head in human subjects

      Optical microangiography provides correlation between microstructure and microvasculature of optic nerve head in human subjects

      It is demonstrated that optical microangiography (OMAG) is capable of imaging the detailed microstructure and microvasculature of the in vivo human optic nerve head (ONH), including the prelaminar tissue, the lamina cribrosa, the scleral rim and the vessels in the region of the circle of Zin-Haller. For demonstration, an ultrahigh sensitive OMAG system operating in the 850 nm wavelength region and a 500 kHz A-scan rate resulting in a spatial resolution of ∼ 6     μ m were used. It was shown that OMAG provides superior results for three-dimensional imaging of the ONH compared to conventional optical coherence tomography by simultaneously recording both ...

      Read Full Article
    11. Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes

      Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes

      Glaucoma is a blinding disease for which intraocular pressure (IOP) is the only treatable risk factor. The mean IOP is regulated through the aqueous outflow system, which contains the trabecular meshwork (TM). Considerable evidence indicates that trabecular tissue movement regulates the aqueous outflow and becomes abnormal during glaucoma; however, such motion has thus far escaped detection. The purpose of this study is to describe anovel use of a phase-sensitive optical coherence tomography (PhS-OCT) method to assess pulse-dependent TM movement. For this study, we used enucleated monkey eyes, each mounted in an anterior segment holder. A perfusion system was used to ...

      Read Full Article
    12. In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography

      In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography

      The corneo-scleral limbus contains several biological components, which are important constituents for understanding, diagnosing and managing several ocular pathologies, such as glaucoma and corneal abnormalities. An anterior segment optical coherence tomography (AS-OCT) system integrated with optical microangiography (OMAG) is used in this study to non-invasively visualize the three-dimensional microstructural and microvascular properties of the limbal region. Advantages include first the ability to correct optical distortion of microstructural images enabling quantification of relationships in the anterior chamber angle. Second, microvascular images enable the visualization of the microcirculation in the limbal area without the use of exogenous contrast agents. Third, by combining ...

      Read Full Article
    1-12 of 12
  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. Topics in the News

    1. (12 articles) University of Washington
    2. (12 articles) Ruikang K. Wang
    3. (6 articles) Peng Li
    4. (5 articles) Tueng T. Shen
    5. (4 articles) Lin An
    6. (3 articles) Roberto Reif
    7. (1 articles) Sepideh Hariri
    8. (1 articles) Zhongwei Zhi
    9. (1 articles) Douglas S. Malchow
    10. (1 articles) UTC Aerospace Systems
    11. (1 articles) British Columbia Cancer Agency
    12. (1 articles) Shanghai Jiao Tong University
    13. (1 articles) Singapore Eye Research Institute
    14. (1 articles) Simon Fraser University
    15. (1 articles) Columbia University
    16. (1 articles) Stephen Lam
    17. (1 articles) Pierre M. Lane
    18. (1 articles) Tien Yin Wong
    19. (1 articles) Giuseppe Querques
    20. (1 articles) Francesco Bandello
  3. Popular Articles

  4. Picture Gallery

    In vivo microstructural and microvascular imaging of the human corneo-scleral limbus using optical coherence tomography Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes Optical microangiography provides correlation between microstructure and microvasculature of optic nerve head in human subjects Extended imaging depth to 12 mm for 1050-nm spectral domain optical coherence tomography for imaging the whole anterior segment of the human eye at 120-kHz A-scan rate Noninvasive imaging of pulsatile movements of the optic nerve head in normal human subjects using phase-sensitive spectral domain optical coherence tomography Methods And Systems For Imaging Tissue Motion Using Optical Coherence Tomography Pulsatile motion of the trabecular meshwork in healthy human subjects quantified by phase-sensitive optical coherence tomography Full anterior segment biometry with extended imaging range spectral domain optical coherence tomography at 1340 nm Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography Wide-field optical coherence tomography based microangiography for retinal imaging Line-field confocal optical coherence tomography-Practical applications in dermatology and comparison with established imaging methods Optical coherence tomography detection of changes in inner retinal and choroidal thicknesses in patients with early retinitis pigmentosa