1. Articles from iovs.org

  2. 241-264 of 554 « 1 2 ... 8 9 10 11 12 13 14 ... 21 22 23 »
    1. Morphometric Analysis of Aqueous Humor Outflow Structures with Spectral Domain Optical Coherence Tomography

      Morphometric Analysis of Aqueous Humor Outflow Structures with Spectral Domain Optical Coherence Tomography

      Purpose: To describe morphometric details of the human aqueous humor (AH) outflow microvasculature visualized with 360 degree virtual castings during active AH outflow in cadaver eyes and comparing these structures with corrosion casting studies. Methods: The conventional AH outflow pathways of donor eyes (N=7) and eyes in vivo (N=3) were imaged with spectral-domain optical coherence tomography (SD-OCT) and wide-bandwidth super luminescent diode array during active AH outflow. Digital image contrast was adjusted to isolate AH microvasculature and images were viewed in a 3D viewer. Additional eyes (N=3) were perfused with mock AH containing fluorescent tracer microspheres to ...

      Read Full Article
    2. Factors associated with anterior chamber narrowing with age: an optical coherence tomography study

      Factors associated with anterior chamber narrowing with age: an optical coherence tomography study

      Purpose: To evaluate the effect of age on various anterior segment (AS) parameters in healthy eyes using AS optical coherence tomography (OCT), and to examine their relationship to anterior chamber angle (ACA) narrowing with age. Methods: Three hundred-and-eighty-eight consecutive Korean subjects aged 30 to 89 years were imaged by AS OCT (Visante, version 2.0; Carl Zeiss Meditec, Dublin, CA). Anterior chamber depth (ACD), iris cross-sectional area (IA), iris thickness at 750 and 1,500 microns from the scleral spur (IT750, 1500), iris curvature (IC), lens vault (LV), and anterior chamber area (AA) were determined using Image J software (version ...

      Read Full Article
    3. Relationship among visual field, blood flow, and neural structure measurements in glaucoma

      Relationship among visual field, blood flow, and neural structure measurements in glaucoma

      Purpose:To determine the relationship among visual field, neural structural, and blood flow measurements in glaucoma. Methods:Case-control study. Forty-seven eyes of 42 patients with perimetric glaucoma were age-matched with 27 normal eyes of 27 patients. All patients underwent Doppler Fourier-domain optical coherence tomography to measure retinal blood flow and standard glaucoma evaluation with visual field testing and quantitative structural imaging. Linear regression analysis was performed to analyze the relationship among visual field, blood flow, and structure, after all variables were converted to logarithmic decibel scale. Results:Retinal blood flow was reduced in glaucoma eyes compared to normal eyes (p

      Read Full Article
    4. Structure-Function Relationships between Spectral-Domain OCT and Standard Achromatic Perimetry

      Structure-Function Relationships between Spectral-Domain OCT and Standard Achromatic Perimetry

      Purpose: To explore structure-function relationships in early glaucoma with spectral-domain optical coherence tomography (SD-OCT) and standard achromatic perimetry. Methods: One hundred thirty-six eyes of 97 patients with suspected or early glaucoma were enrolled from the clinical database at UCLA's Glaucoma Division. All patients had good-quality peripapillary retinal nerve fiber layer (RNFL)/optic disc measurements (Optic Disc Cube 200x200, Cirrus HD-OCT) and a reliable 24-2 SITA-Standard Humphrey visual field (VF) within a 6-month period. Correlations of global and sectoral RNFL thickness and rim area (RA) measurements with corresponding global and regional VF sensitivities (both in logarithmic [dB] and 1/Lambert ...

      Read Full Article
    5. Scanning Laser Polarimetry Reveals Status of Retinal Nerve Fiber Layer (RNFL) Integrity in Eyes with Optic Nerve Head Swelling by OCT

      Scanning Laser Polarimetry Reveals Status of Retinal Nerve Fiber Layer (RNFL) Integrity in Eyes with Optic Nerve Head Swelling by OCT

      Purpose OCT shows retinal nerve fiber layer (RNFL) thickening in optic nerve head (ONH) swelling, but does not provide information on acute axonal disruption. We hypothesized that scanning laser polarimetry (SLP) in comparison with OCT might reveal the status of axon integrity and visual prognosis in acute RNFL swelling. Methods We used threshold perimetry, OCT, and SLP to prospectively study eyes with papilledema (24), optic neuritis (13), NAION (21), and ONH swelling (defined as having average RNFL by OCT > 95th percentile of controls at presentation). Regional RNFL was judged reduced if the OCT or SLP measure in a quadrant was < 5th percentile of controls. Results At presentation, average RNFL by OCT was similar for eyes with papilledema and NAION (p=0.97), and less for optic neuritis. Average RNFL by SLP was less often increased, similar for papilledema and optic neuritis, but less for NAION (p=0.02) eyes. The RNFL by SLP was reduced in at least 1 quadrant in 1/24 eyes with papilledema, 1/14 eyes with optic neuritis, and in 13/21 eyes with NAION. In NAION eyes, quadrants with reduced SLP had corresponding visual field loss that did not recover at 1 or 6 months. By 1 month, eyes with NAION showed RNFL thinning by OCT (7/17 eyes) and by SLP in14/16 eyes) in contrast to optic neuritis (by OCT, 0/12; p=0.006 and by SLP, 1/12; p=0.0004). Conclusion OCT and SLP reveal different aspects of RNFL changes associated with ONH swelling. OCT reveals thickening, due to edema. SLP reveals a decrease in retardance in eyes with axonal injury associated with visual field loss, which is unlikely to recover. This study provides evidence that SLP may be predictive of regions of permanent axon dysfunction and visual field loss in eyes with optic disc edema.

      Read Full Article
    6. Optical Coherence Tomography as a Rapid, Accurate, Noncontact Method of Visualizing the Palisades of Vogt

      Optical Coherence Tomography as a Rapid, Accurate, Noncontact Method of Visualizing the Palisades of Vogt

      Purpose. This study explored the efficacy of optical coherence tomography (OCT) as a high-resolution, noncontact method for imaging the palisades of Vogt by correlating OCT and confocal microscopy images. Methods. Human limbal rims were acquired and imaged with OCT and confocal microscopy. The area of the epithelial basement membrane in each of these sets was digitally reconstructed, and the models were compared. Results. OCT identified the palisades within the limbus and exhibited excellent structural correlation with immunostained tissue imaged by confocal microscopy. Conclusions. OCT successfully identified the limbal palisades of Vogt that constitute the corneal epithelial stem cell niche. These ...

      Read Full Article
    7. Signal quality assessment of retinal optical coherence tomography (OCT) images

      Signal quality assessment of retinal optical coherence tomography (OCT) images

      Purpose: To assess signal quality of retinal OCT images from multiple devices using subjective and quantitative measurements. Methods: 120 multi-frame OCT images from 4 SD OCT devices (Cirrus, RTVue, Spectralis, and 3D OCT-1000) were evaluated subjectively by trained graders, and measured quantitatively using a derived parameter, maximum tissue contrast index (mTCI). An intensity histogram decomposition model was proposed to separate the foreground and background information of OCT images and to calculate the mTCI. The mTCI results were compared to the manufacturer signal index (MSI) provided by the respective devices, and to the subjective grading scores (SGS). Results: Statistically significant correlations ...

      Read Full Article
    8. 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 scattering properties of the RNFL, we used a model that normalized the reflectivity of the RNFL by the retinal pigment epithelium. The analysis was performed at 4 preset locations at ...

      Read Full Article
    9. Classification Algorithms Enhance the Discrimination of Glaucoma from Normal eyes in High Definition Optical Coherence Tomography

      Classification Algorithms Enhance the Discrimination of Glaucoma from Normal eyes in High Definition Optical Coherence Tomography

      Purpose: To evaluate the diagnostic performance of classification algorithms based on Linear Discriminant Analysis (LDA) and Classification And Regression Tree (CART) methods, compared to optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters measured by high-definition optical coherence tomography (Cirrus HD-OCT Version 4.5.1.1, Carl Zeiss Meditec Inc., CA) for discriminating glaucoma subjects. Methods: Consecutive glaucoma subjects (Training data=184; Validation data=102) were recruited from an eye center and normal subjects (n=508) from an ongoing Singaporean Chinese population based study. ONH and RNFL parameters were measured using Optic Disc Cube 200x200 scan protocol. LDA ...

      Read Full Article
    10. Repeatability and reproducibility of manual choroidal volume measurements using enhanced depth imaging optical coherence tomography

      Repeatability and reproducibility of manual choroidal volume measurements using enhanced depth imaging optical coherence tomography

      Purpose: To evaluate the repeatability and reproducibility of manual choroidal volume (CV) measurements on spectral-domain optical coherence tomography (SD-OCT) using enhanced depth imaging (EDI). Methods: Sixty eyes of 32 patients with or without any ocular chorio-retinal diseases were enrolled prospectively. Thirty-one choroidal scans were performed on each eye centered at the fovea using a raster protocol. Two masked observers demarcated choroidal boundaries using the built-in automated retinal segmentation software on two separate sessions. The observers were masked to each other's and their own previous readings. A standardized grid centered on the fovea was positioned automatically by the Spectralis OCT ...

      Read Full Article
    11. Theoretical, Experimental and Optical Coherence Tomography Studies of Graft Apposition and Adhesion in Descemets Stripping Endothelial Keratoplasty

      Theoretical, Experimental and Optical Coherence Tomography Studies of Graft Apposition and Adhesion in Descemets Stripping Endothelial Keratoplasty

      Purpose To investigate the effects of adhesion promoting surgical adjuncts in Descemets stripping automated endothelial kertaoplasty (DSAEK). The effects of air-fill pressure, duration, use of venting incisions and stromal roughening on fluid dispersion and donor adhesion strength were examined in theoretical, optical coherence tomography (OCT) and strain gauge models of DSAEK. Methods OCT analysis: DSAEK modeled using a microkeratome prepared lenticule inserted under a 'recipient' corneo-scleral rim mounted on an artificial anterior chamber. Pressure of 18mmHg (n=6) or 60mmHg (n=6) was applied. The area of interface fluid was measured sequentially. The area of interface fluid before and after ...

      Read Full Article
    12. Reliability and reproducibility of assessment of corneal epithelial thickness by Fourier domain optical coherence tomography

      Reliability and reproducibility of assessment of corneal epithelial thickness by Fourier domain optical coherence tomography

      Purpose: To analyze the intra-user reliability and inter-user reproducibility of assessment of corneal epithelial thickness by Fourier domain optical coherence tomography. Method: In this consecutive cross sectional case series performed at a tertiary ocular care institution 210 eyes of 210 subjects underwent anterior segment Fourier domain optical coherence tomography (FDOCT) with Cirrus HD-OCT. 'Caliper tool' was used to measure the corneal thickness. For reproducibility measures, the examination was done by two examiners (user 1, user 2) within 30 minutes of each other. For reliability measure, the re-test was done by user 1 on the next day, within 30 minutes of ...

      Read Full Article
    13. Glaucoma Diagnostic Ability of Quadrant and Clock-Hour Neuroretinal Rim Assessment Using Cirrus HD Optical Coherence Tomography

      Glaucoma Diagnostic Ability of Quadrant and Clock-Hour Neuroretinal Rim Assessment Using Cirrus HD Optical Coherence Tomography

      Purpose: To investigate the glaucoma diagnostic ability of quadrant and clock-hour neuroretinal rim assessment by Cirrus HD spectral-domain optical coherence tomography (OCT). Methods: Eighty eyes of 80 glaucoma patients and eighty eyes of 80 healthy subjects were enrolled. Peripapillary retinal nerve fiber layer (RNFL) thickness was measured by Cirrus HD-OCT. Quadrant and clock-hour rim areas and thicknesses were obtained from optic nerve head images and 360o circumferential rim thickness curve of Cirrus HD-OCT, respectively. Area under receiver operating characteristic curves (AUCs) and sensitivities of RNFL thicknesses, rim areas, and rim thicknesses at a 90% specificity level were calculated. Results: Quadrant ...

      Read Full Article
    14. Influence of Clinically Invisible, but Optical Coherence Tomography Detected, Optic Disc Margin Anatomy on Neuroretinal Rim Evaluation

      Influence of Clinically Invisible, but Optical Coherence Tomography Detected, Optic Disc Margin Anatomy on Neuroretinal Rim Evaluation

      Purpose: We previously demonstrated that most eyes have regionally variable extensions of Bruch's membrane (BM) inside the clinically identified disc margin (DM) that are clinically and photographically invisible. We studied the impact of these findings on DM and BM opening (BMO) derived neuroretinal rim parameters. Methods: Disc stereo-photography and spectral domain optical coherence tomography (SD-OCT, 24 radial B-scans centred on the optic nerve head) were performed on 30 glaucoma patients and 10 age-matched controls. Photographs were co-localized to SD-OCT data such that the DM and BMO could be visualized in each B-scan. Three parameters were computed: (1) DM-horizontal rim ...

      Read Full Article
    15. Image inversion spectral-domain optical coherence tomography optimizes choroidal thickness and detail through improved contrast

      Image inversion spectral-domain optical coherence tomography optimizes choroidal thickness and detail through improved contrast

      Purpose: To determine whether there were significant differences in choroidal thickness, contrast, outer choroidal vessel (OCV) and choroidal-scleral junction (CSJ) visualization in inverted versus upright spectral-domain optical coherence tomography (SD-OCT). Methods: Images were captured on Bioptigen SD-OCT (Bioptigen Inc., Research Triangle Park, North Carolina), Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc, Dublin, CA), and Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) in 42 eyes of 21 healthy subjects. Average choroidal thickness across a fovea-centered 4 mm segment was determined with MATLAB. Quantitative measures of choroidal contrast were measured and CSJ assessed by applying a 0-3 score. OCV was determined by counting ...

      Read Full Article
    16. Analysis of Progression of Reticular Pseudodrusen by Spectral Domain–Optical Coherence Tomography

      Analysis of Progression of Reticular Pseudodrusen by Spectral Domain–Optical Coherence Tomography

      Purpose. To analyze reticular pseudodrusen progression using spectral domain–optical coherence tomography (SD-OCT). Methods. Thirty-three consecutive patients (48 eyes) underwent SD-OCT using the eye-tracked follow-up protocol 24 ± 2 months after baseline examination. Each pair of B-scans (only one per eye was evaluated among those showing pseudodrusen progression) was compared with respect to pseudodrusen appearance and retinal layer structure. Stage 1 pseudodrusen was defined as granular material between the RPE and the inner segment/outer segment (IS/OS), stage 2 as mounds of material sufficient to alter the contour of the IS/OS, stage 3 as thicker material adopting a conical ...

      Read Full Article
    17. The Physiological Variation of the Retinal Nerve Fiber Layer Thickness and Macular Volume in Humans as Assessed by Spectral Domain–Optical Coherence Tomography

      The Physiological Variation of the Retinal Nerve Fiber Layer Thickness and Macular Volume in Humans as Assessed by Spectral Domain–Optical Coherence Tomography

      Purpose. With the introduction of spectral domain–optical coherence tomography (SD-OCT), changes in retinal nerve fiber layer (RNFL) thickness and macular volume (MV) can be detected with high precision. The aim of this study was to determine whether there is a physiological quantifiable degree of variation of these structures in humans. Methods. This study took place during a 10-km charity run at VU University Medical Center Amsterdam. Weight, height, hydration status, RNFL thickness (ring scan, 12° around the optic nerve head), and MV (20° × 20°) were assessed in 69 subjects (44 runners, 25 controls) using SD-OCT with eye-tracking function. The ...

      Read Full Article
    18. Transsynaptic Retinal Degeneration in Optic Neuropathies: Optical Coherence Tomography Study

      Transsynaptic Retinal Degeneration in Optic Neuropathies: Optical Coherence Tomography Study

      Purpose. Recently demonstrated neuronal loss in the inner nuclear layer of the retina in multiple sclerosis (MS) and glaucoma raises the question of a primary (possibly immune-mediated) or secondary (transsynaptic) mechanism of retinal damage in these diseases. In the present study we used optical coherence tomography to investigate retrograde retinal transsynaptic degeneration in patients with long-standing and severe loss of ganglion cells due to optic neuropathy. Methods. Fifteen eyes of glaucoma patients with visual field defect limited to upper hemifield and 15 eyes of MS patients with previous episode of optic neuritis (ON) and extensive loss of ganglion cells were ...

      Read Full Article
    19. In vivo Assessment of Thickness and Reflectivity in a Rat Outer Retinal Degeneration Model with Ultrahigh Resolution Optical Coherence Tomography

      In vivo Assessment of Thickness and Reflectivity in a Rat Outer Retinal Degeneration Model with Ultrahigh Resolution Optical Coherence Tomography

      Purpose: To provide in vivo quantitative assessment of sodium iodate-induced retinal damage in a rat model of outer retina degeneration using ultrahigh resolution optical coherence tomography (UHR-OCT). Methods: Outer retinal degeneration was induced in 4 female Long Evans rats via tail vein injection of sodium iodate (40 mg/kg). Changes in the thickness and optical reflectivity of individual retinal layers were extracted using a semi-automatic segmentation algorithm and were assessed in vivo at 6 hours, days 1, 3 and 7 and up to 3 months post-injection with UHR-OCT. H & E histology was used to confirm the morphological changes observed in ...

      Read Full Article
    20. Imaging of the Iridocorneal Angle with the RTVue Spectral Domain Optical Coherence Tomography

      Imaging of the Iridocorneal Angle with the RTVue Spectral Domain Optical Coherence Tomography

      Purpose: To determine the ability of the RTVue spectral domain optical coherence tomography (SDOCT) to image the anterior chamber angle (ACA). Methods: Consecutive subjects prospectively underwent ophthalmic evaluation including gonioscopy by an ophthalmologist and anterior chamber imaging with SDOCT (Optovue, Fremont, CA), adapted with a corneal lens adapter (CAM-L module) and anterior segment OCT (ASOCT, Visante, Carl Zeiss Meditec, Dublin, CA), both performed by a technician. Two different ophthalmologists, masked to gonioscopy findings assessed visualization of the scleral spur (SS), Schwalbe's line (SL) and trabecular meshwork (TM) by the two modalities. The ability to detect a closed angle was ...

      Read Full Article
    21. Precision of High Definition Spectral-Domain Optical Coherence Tomography for Measuring Central Corneal Thickness

      Precision of High Definition Spectral-Domain Optical Coherence Tomography for Measuring Central Corneal Thickness

      Purpose: To assess the reliability of central corneal thickness (CCT) measurements using Cirrus high-definition optical coherence tomography (HD-OCT) in healthy subjects and its accuracy compared with ultrasonic pachymetry. Methods: Seventy-seven consecutive subjects were recruited for evaluating repeatability, and agreement between two examiners. To analyze repeatability, one examiner measured 77 eyes four times in succession. To study agreement between two observers, a second independently-trained examiner obtained another CCT measurement. We also measured eyes in a subgroup of 20 patients using standard ultrasonic pachymetry. Within-subject standard deviation (Sw), coefficient of variation (CV), limits of agreement (LoA), and intraclass correlation coefficient (ICC) data ...

      Read Full Article
    22. Repeatability and Reproducibility of Subfoveal Choroidal Thickness in Normal Eyes of Japanese Using Different SD-OCT Devices

      Repeatability and Reproducibility of Subfoveal Choroidal Thickness in Normal Eyes of Japanese Using Different SD-OCT Devices

      Purpose. To compare subfoveal choroidal thickness (SCT) measurements of three different commercially available spectral-domain optical coherence tomography instruments with healthy eyes of Japanese. Methods. A prospective, cross-sectional study was performed at a single institution. SCT of the right eye of 43 normal subjects was measured using three different SD-OCTs: Heidelberg Spectralis-OCT (Spectralis), Cirrus HD-OCT (Cirrus), and Topcon 3D OCT-1000 Mark II (Topcon). Two separate measurements were performed for the same eye with a maximum by a single examiner. SCT was defined as the distance from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction. After manual ...

      Read Full Article
    23. Effect of Spectrum Bias on the Diagnostic Accuracy of Spectral-Domain Optical Coherence Tomography in Glaucoma

      Effect of Spectrum Bias on the Diagnostic Accuracy of Spectral-Domain Optical Coherence Tomography in Glaucoma

      Purpose. To evaluate the influence of a control group on the diagnostic accuracy of spectral-domain optical coherence tomography (SD-OCT) in early glaucoma. Methods. In a diagnostic, case–control study, 119 eyes of 60 normal subjects with no findings suspicious for glaucoma (control cohort 1); 76 eyes of 41 subjects referred by general ophthalmologists as glaucoma suspects based on optic disc morphology, but found by glaucoma experts to be normal but with physiological variations in their optic nerves (control cohort 2); and 65 eyes of 46 early-glaucoma patients (cases) underwent imaging of the optic nerve head (ONH), retinal nerve fiber layer ...

      Read Full Article
    24. Relationships among Multifocal Electroretinogram Amplitude, Visual Field Sensitivity, and SD-OCT Receptor Layer Thicknesses in Patients with Retinitis Pigmentosa

      Relationships among Multifocal Electroretinogram Amplitude, Visual Field Sensitivity, and SD-OCT Receptor Layer Thicknesses in Patients with Retinitis Pigmentosa

      Purpose. To compare local functional measures, the multifocal electroretinogram (mfERG) and visual field sensitivity, with a local structural measure, spectral domain (SD) optical coherence tomography (OCT), of receptor damage in patients with retinitis pigmentosa (RP). Methods. MfERGs, visual fields, and SD-OCT scans were obtained from 10 patients with RP, ranging in age from 23 to 59 years. Average amplitudes, average linear sensitivities, and average layer thicknesses were measured from within the central 3° and from three concentric annuli located between 3° and 8°, 8° and 15°, and 15° and 24°. A computer program aided manual segmentation and calculated OCT thickness ...

      Read Full Article
    241-264 of 554 « 1 2 ... 8 9 10 11 12 13 14 ... 21 22 23 »
  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