1. Articles from iovs.org

  2. 1-24 of 602 1 2 3 4 ... 23 24 25 »
    1. Cardiac-Gated En Face Doppler Measurement of Retinal Blood Flow Using Swept Source Optical Coherence Tomography at 100,000 Axial Scans per Second

      Cardiac-Gated En Face Doppler Measurement of Retinal Blood Flow Using Swept Source Optical Coherence Tomography at 100,000 Axial Scans per Second

      Purpose: To develop and demonstrate a cardiac gating method for repeatable in vivo measurement of total retinal blood flow (TRBF) in humans using en face Doppler optical coherence tomography (OCT) at commercially available imaging speeds. Methods: A prototype swept-source OCT system operating at 100 kHz axial scan rate was developed and interfaced with a pulse oximeter. Using the plethysmogram measured from the earlobe, Doppler OCT imaging of a 1.5 mm×2 mm area at the optic disc at 1.8 volumes/sec was synchronized to cardiac cycle to improve sampling of pulsatile blood flow. Post-processing algorithms were developed to ...

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    2. Association between Systemic Hypertension and Macular Thickness Measured by Optical Coherence Tomography

      Association between Systemic Hypertension and Macular Thickness Measured by Optical Coherence Tomography

      Purpose: This study aimed to evaluate an association between hypertension and macular thickness. Methods: Eight hundreds and twenty-seven Korean adults composed of 163 pairs of twins and their family members were included in this population-based cross-sectional study. Macular thickness was measured with optical coherence tomography at nine macular subfields defined by the Early Treatment of Diabetic Retinopathy Study. Cardiometabolic risk factors, including body mass index (BMI), hypertension, diabetes, lipid profiles, and smoking status, were assessed. Linear mixed regression analysis was conducted with consideration of familial correlations and adjustment for covariates. Results: Age-, sex-, and axial length-adjusted analysis showed that systemic ...

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    3. Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System

      Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System

      Purpose. To evaluate the capability of a novel, coaligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ. Methods. Low-amplitude elastic deformations in young and mature rabbit lenses were measured by an US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system coaligned with a focused ultrasound system used to produce a transient force on the lens surface. Uniaxial compressional tests were used to validate the OCE data. Results. The OCE measurements showed that the maximum displacements of the young rabbit lenses were significantly larger than ...

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    4. Morphometry of the trabecular meshwork in vivo in a healthy population using Fourier domain optical coherence tomography

      Morphometry of the trabecular meshwork in vivo in a healthy population using Fourier domain optical coherence tomography

      Purpose: To measure the length, thickness and area of the trabecular meshwork (TM) in vivo using Fourier domain optical coherence tomography (FD-OCT) in a Caucasian population of healthy subjects. Methods: Cross-sectional study of 1,006 healthy subjects. Left eyes were randomly selected. Age, gender, intraocular pressure and spherical refractive error were noted down. The depth and volume of the anterior chamber and the central corneal thickness were measured with Pentacam®, while IOL Master® was used to measure the axial length. The length, thickness and area of the TM were measured through FD-OCT RTVue®. A study was carried out to determine ...

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    5. Agreement Among Spectral-Domain Optical Coherence Tomography, Standard Automated Perimetry, and Stereophotography in the Detection of Glaucoma Progression

      Agreement Among Spectral-Domain Optical Coherence Tomography, Standard Automated Perimetry, and Stereophotography in the Detection of Glaucoma Progression

      Purpose. The purpose of this study was to evaluate the agreement among spectral-domain optical coherence tomography, standard automated perimetry (SAP), and optic disc stereo photography in the detection of glaucomatous progression. Methods. This was an observational cohort study enrolling 246 eyes (148 patients) followed for an average of 31.8 ± 9 months. Images were obtained every 6 to 12 months with optical coherence tomography (OCT), visual field test, and optic disc stereo photography. Progression was determined with OCT using guided progression analysis (GPA) software, in perimetry with Humphrey field analyzer GPA, and by masked assessment of stereo photograph series. Agreement ...

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    6. Measurement of retinal blood flow in normal Chinese American subjects by Doppler Fourier-domain optical coherence tomography

      Measurement of retinal blood flow in normal Chinese American subjects by Doppler Fourier-domain optical coherence tomography

      PURPOSE: To measure total retinal blood flow (TRBF) in normal, healthy Chinese-Americans using semi-automated analysis of Doppler Fourier-domain optical coherence tomography (FD-OCT) scans. METHODS: Two hundred sixty-six normal, healthy Chinese-American participants (266 eyes) were enrolled from The Chinese American Eye Study (CHES). All participants underwent complete ophthalmic examination, including best-corrected visual acuity, indirect ophthalmoscopy and Doppler FD-OCT imaging, using the circumpapillary double circular scan protocol. TRBF and other vascular parameters (e.g. venous and arterial cross-sectional area and their velocities) were calculated using Doppler OCT of Retinal Circulation software. Associations between TRBF and other clinical parameters were assessed using bivariate ...

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    7. Aqueous Cell Differentiation in Anterior Uveitis Using Fourier-domain Optical Coherence Tomography

      Aqueous Cell Differentiation in Anterior Uveitis Using Fourier-domain Optical Coherence Tomography

      Purpose: The differential diagnosis of a patient presenting with anterior uveitis is broad and can present a diagnostic challenge. In this study, we evaluate the characteristic findings of inflammatory cells on optical coherence tomography (OCT) both in vitro and in vivo. Methods: Blood from two healthy volunteers was prepared using standardized methods for cell sorting with a flow cytometer (FASCAria; BD Biosciences). Neutrophils, lymphocytes, monocytes, and red blood cells were placed in suspension and scanned with a 26 kHz Fourier-domain OCT system (RTVue; Optovue, Inc.) with 5 µm axial resolution. Custom software algorithms were used to identify cells based on ...

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    8. Adaptive Optics Microperimetry and OCT Images Show Preserved Function and Recovery of Cone Visibility in Macular Telangiectasia Type 2 Retinal Lesions

      Adaptive Optics Microperimetry and OCT Images Show Preserved Function and Recovery of Cone Visibility in Macular Telangiectasia Type 2 Retinal Lesions

      Purpose. To evaluate visual function and disease progression in the retinal structural abnormalities of three patients from two unrelated families with macular telangiectasia (MacTel) type 2. Methods. Adaptive optics scanning laser ophthalmoscopy (AOSLO) and AOSLO microperimetry (AOMP) were used to evaluate the structure and function of macular cones in three eyes with MacTel type 2. Cone spacing was estimated using histogram analysis of intercone distances, and registered spectral-domain optical coherence tomography (SD-OCT) scans were used to evaluate retinal anatomy. AOMP was used to assess visual sensitivity in and around areas of apparent cone loss. Results. Although overall lesion surface area ...

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    9. Assessing age-related changes in the biomechanical properties of rabbit lens using a co-aligned ultrasound and optical coherence elastography system

      Assessing age-related changes in the biomechanical properties of rabbit lens using a co-aligned ultrasound and optical coherence elastography system

      Purpose: To evaluate the capability of a novel co-aligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ. Methods: Low-amplitude elastic deformations in young and mature rabbit lenses were measured by the US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system co-aligned with focused ultrasound used to produce a transient force on the lens surface. Uniaxial compressional tests were used to confirm the OCE data. Results: The OCE measurements showed that the maximum displacements of the young rabbit lenses were significantly larger than those of ...

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    10. Agreement between SD-OCT, Standard Automated Perimetry and Stereophotography in the detection of glaucomatous progression

      Agreement between SD-OCT, Standard Automated Perimetry and Stereophotography in the detection of glaucomatous progression

      PURPOSE. To evaluate the agreement between spectral domain optical coherence tomography, standard automated perimetry and optic disc stereophotos in the detection of glaucomatous progression. METHODS. Observational cohort study enrolling 246 eyes (148 patients) followed-up for an average of 31.8 ± 9 months. Images were obtained every 6-12 months with optical coherence tomography, visual field and optic disc stereophotos. Progression was determined in OCT with the Glaucoma Progression Analysis software (GPA), in perimetry with the Humphrey Field Analyzer GPA and by masked assessment of stereophotographs series. Agreement among methods was reported using the Kappa coefficient (K), PABAK (prevalence-adjusted bias-adjusted kappa), Gwet ...

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    11. Change in drusen area over time compared using spectral-domain optical coherence tomography and color fundus imaging

      Change in drusen area over time compared using spectral-domain optical coherence tomography and color fundus imaging

      Purpose. To investigate the relationship between drusen areas measured with color fundus images (CFIs) and those with spectral-domain optical coherence tomography (SDOCT). Methods. Forty-two eyes from thirty patients with drusen in the absence of geographic atrophy were recruited to a prospective study. Digital color fundus images and SDOCT images were obtained at baseline and at follow-up visits at 3 and 6 months. Registered, matched circles centered on the fovea with diameters of 3 mm and 5 mm were identified on both CFIs and SDOCT images. Spectral-domain OCT drusen measurements were obtained using a commercially available proprietary algorithm. Drusen boundaries on ...

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    12. Evaluation of a Method for Estimating Retinal Ganglion Cell Counts Using Visual Fields and Optical Coherence Tomography

      Evaluation of a Method for Estimating Retinal Ganglion Cell Counts Using Visual Fields and Optical Coherence Tomography

      Purpose : To evaluate the accuracy and generalizability of a published model that derives estimates of retinal ganglion cell (RGC) counts and relates structural and functional changes due to glaucoma. Methods : Both the Harwerth et al. non−linear model (H−NLM) and the Hood and Kardon linear model (HK−LM) were applied to an independent dataset of frequency−domain optical coherence tomography and visual fields, consisting of 48 eyes of 48 healthy controls, 100 eyes of 77 glaucoma patients and suspects, and 18 eyes of 14 non−arteritic anterior ischemic optic neuropathy (ION) patients with severe vision loss. Using the coefficient ...

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    13. Lamina Cribrosa Visibility using Optical Coherence Tomography: Comparison of Devices and Effects of Image Enhancement Techniques

      Lamina Cribrosa Visibility using Optical Coherence Tomography: Comparison of Devices and Effects of Image Enhancement Techniques

      Purpose: To compare the visibility of the lamina cribrosa (LC) in optic disc images acquired from 60 glaucoma and 60 control subjects using three optical coherence tomography (OCT) devices, with and without enhanced depth imaging (EDI) and adaptive compensation (AC). Methods: A horizontal B-scan was acquired through the centre of the disc using two spectral-domain (Spectralis and Cirrus; with and without EDI) and a swept-source (DRI) OCT. AC was applied post-acquisition to improve image quality. To assess LC visibility, four masked observers graded the 1,200 images in a randomised sequence. The anterior LC was graded from 0 to 4 ...

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    14. Analysis of Retinal Nonperfusion Using Depth-Integrated Optical Coherence Tomography Images in Eyes with Branch Retinal Vein Occlusion

      Analysis of Retinal Nonperfusion Using Depth-Integrated Optical Coherence Tomography Images in Eyes with Branch Retinal Vein Occlusion

      PURPOSE: To assess the morphology of areas of complete retinal nonperfusion in eyes with branch retinal vein occlusion (BRVO) by enface images of optical coherence tomography (OCT). METHODS: Forty-six eyes with BRVO which underwent swept-source OCT (SS-OCT) and fluorescein angiography were enrolled. Depth-integrated images of the neural retina delineated by automated segmentation algorithm were obtained using SS-OCT. The findings in a 6 x 6-mm area on enface SS-OCT scans at the area of retinal nonperfusion were evaluated. RESULTS: Retinal nonperfusion was detected in twenty-five eyes. Of these, twenty (80%) eyes had multiple concaves of low reflectivity within an area of ...

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    15. The use of time-lapse optical coherence tomography to image the effects of microapplied toxins on the retina

      The use of time-lapse optical coherence tomography to image the effects of microapplied toxins on the retina

      Purpose: We developed a novel technique using a drug microperfusion device and time-lapse optical coherence tomography (OCT) for accelerated drug screening and retinotoxin characterization. Methods: Using an ex vivo rabbit eyecup preparation, we studied retinotoxin effects in real-time by microperfusing small retinal areas under a transparent fluoropolymer tube. Known retinotoxic agents were applied to the retina for 5 minute periods while changes in retinal structure, thickness, and reflectance were monitored with OCT. The OCT images of two agents with dissimilar mechanisms, cyanide and kainic acid, were compared with their structural changes seen histologically. Results: We found the actions of retinotoxic ...

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    16. Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral Domain Optical Coherence Tomography

      Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral Domain Optical Coherence Tomography

      Purpose: To report the retinal nerve fiber layer (RNFL) defect volume deviation according to structural RNFL loss in RNFL thickness maps Methods: RNFL defect is defined in RNFL thickness maps by the degree of RNFL loss. A 20% to 70% degree of RNFL loss was set with a 1% interval as the reference level for determining the boundary of RNFL defects. Each individual RNFL thickness map was compared to a normative database map and the region below the reference level was identified as an RNFL defect. The RNFL defect volume was calculated by summing the volumes of each pixel inside ...

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    17. Intereye Comparison of Cirrus OCT in Early Glaucoma Diagnosis and Detecting Photographic Retinal Nerve Fiber Layer Abnormalities

      Intereye Comparison of Cirrus OCT in Early Glaucoma Diagnosis and Detecting Photographic Retinal Nerve Fiber Layer Abnormalities

      Purpose: To compare the ability of various maps constructed using Cirrus optical coherence tomography (OCT), including the "intereye comparison" derived from the temporal-superior-inferior-nasal-temporal (TSNIT) map, in terms of glaucoma diagnosis and detection of RNFL defects identified in red-free fundus photographs. Methods: This cross-sectional study was conducted on a total of 131 open-angle glaucoma patients with early-stage visual field defects (mean deviation ≤ -6.0 dB) and 56 normal controls. Intereye differences were identified on TSNIT maps constructed by comparing the RNFL thickness curves of both eyes of individual patients and a separation of the RNFL thickness curves of either eye (by ...

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    18. Diagnostic ability of macular nerve fiber layer thickness using a new segmentation software in glaucoma suspects

      Diagnostic ability of macular nerve fiber layer thickness using a new segmentation software in glaucoma suspects

      Purpose. To assess the capacity of internal retinal layer thickness measurements made at the macula using new spectral domain OCT software (Spectralis OCT, Heidelberg Engineering) to distinguish between healthy subjects and those with suspected glaucoma. The diagnostic performance of such measurements was also compared with that of conventional peripapillary retinal nerve fiber layer (RNFL) thickness measurements. Methods. The study included 38 subjects with suspected glaucoma and 38 age-matched healthy subjects. In one randomly selected eye of each participant, thickness measurements at the level of the macula were made of the nerve fiber layer (mRNFL), the ganglion cell layer (GCL) and ...

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    19. Additive Diagnostic Role of Imaging in Glaucoma: Optical Coherence Tomography and Retinal Nerve Fiber Layer Photography

      Additive Diagnostic Role of Imaging in Glaucoma: Optical Coherence Tomography and Retinal Nerve Fiber Layer Photography

      Purpose: To investigate the additive diagnostic role of spectral-domain optical coherence tomography (SD-OCT) and red-free retinal nerve fiber layer photography (RNFLP) in making clinical glaucoma diagnosis. Methods: Four diagnostic combination sets, including the most recent image from each measurement of 196 glaucoma eyes (including the 44 preperimetric glaucoma eyes) and 101 healthy eyes, were prepared: (1) stereo disc photography and Humphrey visual field (SH); (2) SH and SD-OCT (SHO); (3) SH and RNFLP (SHR); 4) SHR and SD-OCT (SHRO). Each randomly sorted set was serially presented at one-month intervals to five glaucoma specialists who were asked to evaluate them in ...

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    20. Optical Coherence Tomography Study of Retinal Changes in Normal Aging and after Ischemia

      Optical Coherence Tomography Study of Retinal Changes in Normal Aging and after Ischemia

      Purpose. Age-related thinning of the retinal ganglion cell axons in the nerve fiber layer has been measured in humans using optical coherence tomography (OCT). In this study, we used OCT to measure inner retinal changes in 3-months-, one-year, and two-year-old mice and after experimental anterior ischemic optic neuropathy (AION). Methods. We used OCT to quantify retinal thickness in over 200 eyes at different ages before and after photochemical thrombosis model of AION. The scans were manually or automatically segmented. Results. In normal aging, there was 1.3 µm thinning of the ganglion cell complex (GCC) between 3-months and 1-year (P ...

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    21. Monitoring of strain-dependent responsiveness to TLR activation in the mouse anterior segment using SD-OCT

      Monitoring of strain-dependent responsiveness to TLR activation in the mouse anterior segment using SD-OCT

      Purpose: To determine whether spectral-domain optical coherence tomography (SD-OCT) can be used to longitudinally monitor inflammation in the mouse anterior segment and to identify any strain-dependent differences in responsiveness to distinct toll-like receptor ligands. Methods: Corneal inflammation was induced in BALB/c and C57BL/6 mice following central corneal abrasions and topical application of saline, toll-like receptor (TLR)-4 ligand, lipopolysaccharide (LPS) or TLR9 ligand, CpG-ODN (CpG). Anterior-segment images were captured using SD-OCT at baseline, 24 hours and one-week post-treatment. Corneal thickness, stromal haze and the number of keratic precipitates (KP) and anterior chamber (AC) cells were longitudinally compared to ...

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    22. Baseline OCT Measurements in the Idiopathic Intracranial Hypertension Treatment Trial: Part II. Correlations and Relationship to Clinical Features

      Baseline OCT Measurements in the Idiopathic Intracranial Hypertension Treatment Trial: Part II. Correlations and Relationship to Clinical Features

      Purpose: The accepted method to evaluate and monitor papilledema, Frisén grading, is an ordinal approach based on descriptive features. Part I showed spectral domain (SD) optical coherence tomography (OCT) in a clinical trial setting provides reliable measurement of the effects of papilledema on the optic nerve head (ONH) and peripapillary retina, particularly if a 3D-segmentation method is used for analysis.1 We evaluated how OCT parameters are interrelated and how they correlate with vision and other clinical features in idiopathic intracranial hypertension (IIH). Methods: 126 subjects in the IIH Treatment Trial (IIHTT) OCT substudy had Cirrus SD-OCT optic disc ...

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    23. Baseline OCT Measurements in the Idiopathic Intracranial Hypertension Treatment Trial: Part I. Quality Control,Comparisons and Variability

      Baseline OCT Measurements in the Idiopathic Intracranial Hypertension Treatment Trial: Part I. Quality Control,Comparisons and Variability

      Purpose: Optical coherence tomography (OCT) has been utilized to investigate papilledema in single site, mostly retrospective studies. We investigated whether spectral domain OCT (SD-OCT), which provides thickness and volume measurements of the optic nerve and retina, could reliably demonstrate structural changes due to papilledema in a prospective multi-site clinical trial setting. Methods: At entry, 126 subjects in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) with mild visual field loss had optic disc and macula scans using the Cirrus SD-OCT. Images were analyzed using the proprietary commercial and custom 3-D segmentation algorithms to calculate retinal nerve fiber layer (RNFL), total retinal ...

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    24. Optical coherence tomography and confocal microscopy following 3 different protocols of corneal collagen-crosslinking in keratoconus.

      Optical coherence tomography and confocal microscopy following 3 different protocols of corneal collagen-crosslinking in keratoconus.

      Purpose: To compare the efficacy and early morphological changes in the cornea following conventional (C-CXL), transepithelial by iontophoresis (I-CXL), and accelerated collagen cross-linking (A-CXL) in keratoconus. Methods: 45 eyes of 45 patients with progressive keratoconus who underwent corneal collagen crosslinking (CXL) were divided into 3 groups: C-CXL (n=15), A-CXL (n=15) and I-CXL (n=15). Patients were examined before surgery and at 1-month, 3-month, and 6-month intervals following surgery. Density of corneal sub-basal nerves, anterior and posterior keratocytes, corneal endothelium, demarcation line depth and maximal simulated keratometry values (Kmax) were all assessed. Results: Compared with preoperative values, the mean ...

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