1. Articles in category: Ophthalmology

    11569-11592 of 11968 « 1 2 ... 480 481 482 483 484 485 486 ... 497 498 499 »
    1. Line-Field Optical Coherence Tomography Using Frequency-Sweeping Source

      In this paper, we propose a line-field optical coherence tomography (OCT) with frequency-sweeping source, which uses imaging optics to form a line focus on the sample and obtains cross-sectional OCT images of biological tissues without any mechanical scanning. Therefore, real-time imaging becomes possible even when the sweeping rate of the source is not high. Moreover, a full 3-D volume image can be acquired by simply incorporating 1-D mechanical scanning. Our line-field OCT using frequency-sweeping source has a sensitivity of $sim$ 88 dB, an axial resolution of 8.3 $mu$m, and an acquisition speed of 45 fps.
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    2. Anterior segment imaging: ultrasound biomicroscopy and anterior ...

      Abstract: Purpose of review: Recent advances in ocular imaging have included high-resolution techniques for visualizing the anterior segment and angle structures. This review will describe the two main anterior segment imaging modalities and summarize their applications, strengths and weaknesses. Recent findings: Ultrasound biomicroscopy and more recently anterior segment optical coherence tomography are imaging modalities that can be used to obtain two-dimensional images of the angle and surrou
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    3. New developments in optical coherence tomography for glaucoma.

      Abstract: Purpose of review: Structural imaging is becoming a powerful adjunct for the diagnosis and progression of glaucoma. There are several competing technologies in this arena. Optical coherence tomography continues to evolve at a fast pace, so it can be challenging to keep up with the latest information. This review covers the recent papers relevant to optical coherence tomography for glaucoma. Recent findings: Retinal nerve fiber layer imaging by optical coherence tomography is reliable.
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    4. Relationships of Retinal Vessel Diameters with Optic Disc, Macular and Retinal Nerve Fiber Layer Parameters in 6-year old Children.

      Purpose: To describe the normal anatomical relationships of retinal vessel diameters with optic disc, macula, and retinal nerve fiber layer parameters in young children. Methods: We conducted a population-based, cross-sectional study of 1,204 healthy children aged 6 years participating in the Sydney Childhood Eye Study. Retinal arteriolar and venular diameters were measured from fundus photographs using standardized computer-based METHODS: Optical coherence tomography was performed to obtain measurements of the optic disc, macular, and retinal nerve fiber layer parameters. Results: In multivariate analysis, each standard deviation (SD) decrease in optic disc area was associated with 0.14 pixel decrease (p ...
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    5. Spectrometer based Fourier domain optical coherence tomography of the mouse retina

      We present a custom Fourier Domain Optical Coherence Tomography (FDOCT) system adapted to imaging the retinal structures in mice. The FDOCT system utilized spectrometer detection, and operated at a central wavelength of 826nm with a FWHM spectral bandwidth of 72nm, corresponding to an axial resoluti ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 684731 (2008)] published Mon Feb 18, 2008.
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    6. Retinal blood flow measurement by using optical coherence tomography

      Shuichi Makita, Tapio Fabritius, Masahiro Miura et al. Quantification of the three-dimensional (3D) retinal vessel structure and blood flow is demonstrated. 3D blood flow distribution is obtained by Doppler optical coherence angiography (D-OCA). Vessel parameters, i.e. diameter, orientation, and position, are determined in an en face vessel image. The D ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68470J (2008)] published Mon Feb 18, 2008.
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    7. In vivo retinal blood flow measurement by Fourier domain Doppler optical coherence tomography

      The measurement of ocular blood flow is important in studying the pathophysiology and treatment of several leading causes of blindness. We present a method for in vivo human retinal flow measurement using Fourier domain optical coherence tomography. A double circular scanning pattern was used to sca ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 68470G (2008)] published Mon Feb 18, 2008.

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    8. Segmentation of the retinal pigment epithelium by polarization sensitive optical coherence tomography

      Christoph K. Hitzenberger, Erich Gotzinger, Michael Pircher et al. We report on a new method for segmenting the retinal pigment epithelium (RPE) in polarization sensitive optical coherence tomography (PS-OCT) images of the human retina. Contrary to previous segmentation algorithms that were based on variations of backscattered intensity between individual layers, o ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 684705 (2008)] published Mon Feb 18, 2008.
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    9. Finite difference time-domain model of light scattering from retinal photoreceptors

      Samer Abdallah, Alex Iolov, Omar M. Ramahi et al. Functional ultra high resolution optical coherence tomography (fUHROCT) was used to non-invasively probe the functional response of retinal photoreceptors. Using this technique, time dependent changes in light reflectivity of the retinal photoreceptor layer were measured after external white light s ... [Proc. SPIE Int. Soc. Opt. Eng. 6864, 68640H (2008)] published Fri Feb 15, 2008.
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    10. Reviewing the AC Cornea OCT

      New optical coherence technology on the horizon may allow surgeons a better way to image opaque corneas he AC Cornea OCT (Ophthalmic Technologies Inc., Toronto, Canada) was reviewed by researchers at The New York Eye & Ear Infirmary Retina Center, and found to be useful in a variety of ways, although there were some drawbacks. “Its noninvasive technique allows imaging of eyes following trauma, after surgery, or with active infections,” wrote lead study author Julian P. S. Garcia Jr., M.D., New Y
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    11. OCT identifies poor wound architecture

      Study finds poor wound architecture and endophthalmitis risk is more common with low IOP n investigation of clear corneal incision (CCI) architecture in the immediate post-op period with optical coherence tomography (OCT) identified shortcomings such as endothelial gaping and loss of coaptation. Those problems—more common at low intraocular pressure—could represent significant endophthalmitis risk factors. The study of the popular type of cataract incision comes as the rate of endophthalmitis af
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    12. Spectral Optical Coherence Tomography in Video-Rate and 3D Imaging of Contact Lens Wear

      Optometry & Vision Science. 84(12):E1104-E1109, December 2007. KALUZNY, BARTLOMIEJ J. MD, PhD; FOJT, WOJCIECH Dipl Ing; SZKULMOWSKA, ANNA MSc; BAJRASZEWSKI, TOMASZ MSc; WOJTKOWSKI, MACIEJ PhD; KOWALCZYK, ANDRZEJ PhD Abstract: Purpose. To present the applicability of spectral optical coherence tomography (SOCT) for video-rate and three-dimensional imaging of a contact lens on the eye surface. Methods. The SOCT prototype instrument constructed at Nicolaus Copernicus University (Torun, Poland) is b
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    13. Die Rolle des Stratus-OCT bei der Anti-VEGF-Therapie

      Background The evaluation of OCT3 during anti-VEGF therapy. Methods A total of 29 patients with choroidal neovascularization secondary to AMD received 3 intravitreal injections of ranibizumab. OCT examination and visual acuity testing (ETDRS) were performed before therapy onset, after 1 week and after 1, 2 and 3 months. Results The central retinal thickness (CRT) was assessed correctly by OCT in 128 out of 145 measurements. There was a distinct (84%) but not significant correlation between decrease in central retinal thickness and increase in visual acuity. Incorrect retinal layer segmentation and inadequate CRT measurements were a significant technical limitation. Conclusion During ...

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    14. Dynamics of small-incision clear cornea wounds after phacoemulsification surgery using optical coherence tomography in the early postoperative period.

      Dynamics of small-incision clear cornea wounds after phacoemulsification surgery using optical coherence tomography in the early postoperative period. J Refract Surg. 2008 Jan;24(1):46-9 Authors: Behrens A, Stark WJ, Pratzer KA, McDonnell PJ PURPOSE: To evaluate wound dynamics in the immediate postoperative period after phacoemulsification surgery using a small-incision clear cornea approach. METHODS: Eight patients underwent standard postoperative evaluation 24 hours after uneventful phacoemulsification surgery performed through a temporal or nasal clear corneal incision. Additional screening was performed with non-contact optical coherence tomography (Visante Anterior Segment OCT) to examine the corneal wounds. RESULTS: One patient showed partial spontaneous ...
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    15. Automated method for RNFL segmentation in spectral domain OCT

      Amit S. Paranjape, Badr Elmaanaoui, Jordan Dewelle et al. We introduce a method based on optical reflectivity changes to segment the retinal nerve fiber layer (RNFL) in images recorded using swept source spectral domain optical coherence tomography (OCT). The segmented image is used to determine the RNFL thickness. Simple filtering followed by edge detecti ... [Proc. SPIE Int. Soc. Opt. Eng. 6848, 68480N (2008)] published Tue Feb 12, 2008.
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    16. Optical coherence tomography imaging for evaluating the photo biomodulation effects on tissue regeneration in the oral cavity

      Craig B. Gimbel Optical Coherence Tomography (OCT) is a noninvasive method for imaging dental microstructure which has the potential of evaluating the health of periodontal tissue. OCT provides an "optical biopsy" of tissue 2-3 mm in depth. Optical biopsy is a measurement of the localized optical properties based o ... [Proc. SPIE Int. Soc. Opt. Eng. 6846, 68460H (2008)] published Tue Feb 12, 2008.
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    17. High-penetration imaging of retinal and choroidal pathologies by 1 um swept-source OCT and optical coherence angiography

      Yoshiaki Yasuno, Masahiro Miura, Fumiki Okamoto et al. Two pathologic cases are evaluated by high-penetration optical coherence tomography (HP-OCT) to demonstrate its clinical significance. The HP-OCT is based on a swept-source OCT (SS-OCT) technology with a probe wavelength of 1.06 [mu]m. The depth resolution is 10.4 [mu]m in tissue, and the measuremen ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68441H (2008)] published Mon Feb 11, 2008.
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    18. Direct visualization of tear film on soft contact lens using ultra-high resolution spectral domain optical coherence tomography

      Jianhua Wang, Shuliang Jiao, Marco Ruggeri et al. The integrity of the tear film on the surface of contact lenses is essential to maintaining visual clarity and the overall health of the superficial structures of the eye (cornea and conjunctiva) for contact lens wearers. It is very critical to evaluate pre- and post-lens tear films in contact lens ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68441E (2008)] published Mon Feb 11, 2008.
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    19. Imaging the anterior eye segment by polarization-sensitive spectral-domain and swept-source optical coherence tomography

      Masahiro Miura, Masahiro Yamanari, Toyohiko Yatagai et al. Polarization-sensitive optical coherence tomography (PS-OCT) has been developed to measure the birefringent properties of the human eye. In the retina, retinal nerve fiber layer and retinal pigment epitherial layer have the characteristic birefringent properties. In addition to such normal tissue, a ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68441C (2008)] published Mon Feb 11, 2008.
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    20. Frequency encoded optical assessment of human retinal physiology

      Rainer A. Leitgeb, Roland Michaely, Adrian Bachmann et al. We demonstrate in-vivo functional imaging of the human retina with Fourier domain optical coherence tomography employing frequency encoding of an excitation pattern. The principle is based on projecting a modulated rectangular pattern across the foveal region and acquiring a time series of B-Scans a ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440I (2008)] published Mon Feb 11, 2008.

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    21. Improved sensitivity measurement of the human eye length in vivo with Fourier domain optical coherence tomography

      Branislav Grajciar, Michael Pircher, Christoph K. Hitzenberger et al. We present a system for intraocular distance measurement of the human eye in vivo with high sensitivity. The instrument is based on Fourier domain low coherence interferometry (FD-LCI). State-of-the-art FD-LCI systems are capable to image a depth range of only a few mm, because the depth range is de ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440L (2008)] published Mon Feb 11, 2008.

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    22. Retinal blood flow analysis using joint spectral and time domain optical coherence tomography

      Anna Szkulmowska, Maciej Szkulmowski, Tomasz Bajraszewski et al. We propose a new technique of measuring and analysis of OCT signals: joint Spectral and Time domain Optical Coherence Tomography (STdOCT). This technique is based on a multiple spectral interferogram registration in time increments. The analysis of a single spectral interferogram provides an axial s ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440K (2008)] published Mon Feb 11, 2008.
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    23. Mapping of photoreceptor dysfunction using high resolution three-dimensional spectral optical coherence tomography

      B. L. Sikorski, M. Szkulmowski, J. J. Kaluzny et al. The ability to obtain reliable information on functional status of photoreceptor layer is essential for assessing vision impairment in patients with macular diseases. The reconstruction of three-dimensional retinal structure in vivo using Spectral Optical Coherence Tomography (Spectral OCT) became p ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440J (2008)] published Mon Feb 11, 2008.
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    11569-11592 of 11968 « 1 2 ... 480 481 482 483 484 485 486 ... 497 498 499 »
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