1. Articles from iovs.org

  2. 241-264 of 603 « 1 2 ... 8 9 10 11 12 13 14 ... 24 25 26 »
    1. Associations between Local Retinal Thickness and Function in Early Diabetes

      Associations between Local Retinal Thickness and Function in Early Diabetes

      Purpose. To investigate, using multifocal electroretinography (mfERG) and optical coherence tomography (OCT), potential spatial associations between local neuroretinal function and local retinal thickness in patients with diabetes. Methods. Forty-five patients without retinopathy (10 with Type 1 diabetes; 35 with Type 2 diabetes; 49.9 ± 10.9 years old) and 29 age-similar controls (47.0 ± 12.8 years old) were studied. N1-P1 amplitude (AMP) and P1 implicit time (IT) of mfERGs within the central approximately 20° diameter were compared to spatially corresponding full retinal thickness measurements acquired by Stratus OCT3. AMP and IT were converted to Z-scores and retinal thickness was ...

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    2. Retinal Nerve Fiber Layer Thickness Reproducibility Using Seven Different OCT Instruments

      Retinal Nerve Fiber Layer Thickness Reproducibility Using Seven Different OCT Instruments

      Purpose. The clinical utility of new optical coherence tomography (OCT) instruments strongly depends on measurements reproducibility. The aim of this study was to assess retinal nerve fiber layer (RNFL) thickness reproducibility using six different spectral-domain OCTs (SD-OCTs) and one time-domain OCT. Methods. RNFL thickness (average and four quadrant) from six SD-OCTs (Spectral OCT/SLO OPKO/OTI, 3D-OCT 2000 Topcon, RS-3000 NIDEK, Cirrus HD-OCT Zeiss, RTVue-100 Optovue, and Spectralis Heidelberg) and one time-domain OCT (Stratus OCT Zeiss) was measured twice in 38 right eyes of 38 randomly chosen healthy volunteers by two masked operators. Inter- and intraoperator reproducibility was evaluated by ...

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    3. Stimulus Specific Pupil Dynamics Measured in Birds (Gallus Gallus Domesticus) in vivo with Ultrahigh Resolution Optical Coherence Tomography

      Stimulus Specific Pupil Dynamics Measured in Birds (Gallus Gallus Domesticus) in vivo with Ultrahigh Resolution Optical Coherence Tomography

      Purpose:To demonstrate the ability of high speed, ultra-high resolution optical coherence tomography (UHR-OCT) to measure and characterize in vivo visual stimulus specific pupil dynamics in birds. Methods:Ten two-week old White Leghorn (Gallus gallus domesticus) chickens were imaged in this study. The chickens were dark adapted for one hour and anesthetized with 2% isoflurane prior to the imaging procedure. Blue, green, and red single flash visual stimuli of 7ms duration were used to evoke pupillary responses. UHR-OCT cross-sectional images of the pupil were acquired prior, during and for several seconds after the visual stimuli onset. Images were processed with ...

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    4. Behavior of SD-OCT–Detected Hyperreflective Foci in the Retina of Anti-VEGF–Treated Patients with Diabetic Macular Edema

      Behavior of SD-OCT–Detected Hyperreflective Foci in the Retina of Anti-VEGF–Treated Patients with Diabetic Macular Edema

      Purpose. Hyperreflective foci (HFs) are observable within the neurosensory retina in diabetic macular edema (DME) using spectral domain optical coherence tomography (SD-OCT). HFs have also been seen in wet age-related macular degeneration (AMD), although the origin is still unknown; however, they reduced significantly during anti-VEGF (vascular endothelial growth factor) therapy, and their baseline amount seemed to correlate with treatment success. In this study the behavior of HFs was evaluated during anti-VEGF therapy for DME. Methods. Fifty-one patients (mean age: 67 years) underwent SD-OCT before and one month after one anti-VEGF injection (ranibizumab: n = 30; bevacizumab: n = 21). The HFs were ...

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    5. Influence of Anterior Segment Power on the Scan Path and RNFL Thickness Using SD-OCT

      Influence of Anterior Segment Power on the Scan Path and RNFL Thickness Using SD-OCT

      Purpose. Retinal nerve fiber layer (RNFL) thickness measures with spectral domain-optical coherence tomography (SD-OCT) provide important information on the health of the optic nerve. As with most retinal imaging technologies, ocular magnification characteristics of the eye must be considered for accurate analysis. While effects of axial length have been reported, the effects of anterior segment optical power on RNFL thickness measures have not been described fully to our knowledge. The purpose of our study was to determine the influence of the optical power change at the anterior corneal surface, using contact lenses, on the location of the scan path and ...

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    6. Determinants of Ganglion Cell–Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Determinants of Ganglion Cell–Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Purpose. To determine the distribution, variation, and determinants of ganglion cell–inner plexiform layer (GC-IPL) thickness in nonglaucomatous eyes measured by high-definition optical coherence tomography (HD-OCT). Methods. Six hundred twenty-three Chinese adults aged 40 to 80 years were consecutively recruited from a population-based study. All subjects underwent a standardized interview, ophthalmic examination, and automated perimetry. HD-OCT with macular cube protocol was used to measure the GC-IPL thickness. Univariate and multiple linear regression analyses were performed to examine the relationship between GC-IPL thickness with ocular and systemic factors. Results. The mean (±SD) age of study subjects was 52.84 ± 6.14 ...

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    7. Correlation of SD-OCT Features and Retinal Sensitivity in Neovascular Age-related Macular Degeneration

      Correlation of SD-OCT Features and Retinal Sensitivity in Neovascular Age-related Macular Degeneration

      Purpose: To correlate retinal sensitivity in patients with neovascular age-related macular degeneration (AMD) with specific characteristics of retinal morphology. Methods: Thirty eyes of 30 patients presenting with active choroidal neovascularization were examined by spectral domain optical coherence tomography (SD-OCT) and microperimetry (MP1). Image processing software was used to match a fundus photographic (FP) MP1 image with an infrared+OCT SD-OCT image. Each MP test point for retinal sensitivity was positioned at the corresponding SD-OCT location, and the microperimetric results were evaluated. Results: An intact retinal configuration was associated with a median retinal sensitivity of 15.5 dB [quartiles: 12dB, 18dB ...

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    8. 'En face' OCT imaging of the IS/OS junction line in Type 2 Idiopathic Macular Telangiectasia

      'En face' OCT imaging of the IS/OS junction line in Type 2 Idiopathic Macular Telangiectasia

      Purpose: To investigate abnormalities of the photoreceptor inner/outer segment (IS/OS) junction layer viewed 'en face' and their functional correlates in Type 2 Idiopathic Macular Telangiectasia (type 2 MacTel). Methods: Segmentation and 'en face' imaging of the IS/OS lines in spectral domain optical coherence tomographic (SD-OCT) volumes were performed manually. Mesopic retinal sensitivity thresholds were determined using a Nidek MP1 microperimeter. 'En face' SD-OCT images and microperimetric data were superimposed over images of the fundus. Retinal structure and characteristics of type 2 MacTel were analyzed, associations of structural changes with function were investigated. Results: Forty-nine eyes of 28 ...

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    9. 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 utilizes the retinal pigment epithelium as a reference layer. The attenuation coefficient describes the attenuation of light in tissue due to scattering and absorption. En-face maps were constructed and visually ...

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    10. Measurement of Absolute Blood Flow Velocity and Blood Flow in the Human Retina by Dual-beam Bidirectional Doppler Fourier-Domain Optical Coherence Tomography

      Measurement of Absolute Blood Flow Velocity and Blood Flow in the Human Retina by Dual-beam Bidirectional Doppler Fourier-Domain Optical Coherence Tomography

      Purpose The present experiments were undertaken to evaluate the validity of absolute flow velocity measurements using a dual-beam bidirectional Doppler Fourier-domain optical coherence tomography (FD-OCT) system. Methods The flow velocities of diluted milk through a glass capillary were measured at 30 different preset velocities in the range of 0.9 to 39.3 mm/s by bidirectional Doppler FD-OCT. The flow through the capillary was controlled by two infusion pumps working in different flow ranges and based on different technical principles. In vivo the validity of the method for measuring blood flow in retinal vessels was tested at bifurcations. The ...

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    11. Characterization of vitreoretinal interface disorders using OCT in the interventional phase 3 trials of ocriplasmin

      Characterization of vitreoretinal interface disorders using OCT in the interventional phase 3 trials of ocriplasmin

      PURPOSE: To determine the reproducibility of a novel optical coherence tomography (OCT) protocol designed to formally evaluate vitreoretinal interface abnormalities on scans obtained during two phase3 studies of intravitreal ocriplasmin to treat symptomatic vitreomacular adhesion with or without macular hole. METHODS: Certified technicians obtained time-domain OCT scans that included a Macular Thickness Map (MTM), Fast MTM, and three high resolution linear scans: one 10 mm horizontal and one 10 mm vertical through the optic nerve head (ONH) and one 10 mm 5-degree-offset through the ONH and fovea. Reading Center teams graded all 3695 scans from 652 study eyes for pre-established ...

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    12. Enhanced depth imaging optical coherence tomography in type 2 diabetes

      Enhanced depth imaging optical coherence tomography in type 2 diabetes

      Purpose: To investigate the changes in macular choroidal thickness in eyes with various stages of diabetic retinopathy, using enhanced depth imaging optical coherence tomography (EDI OCT). Methods: Sixty-three consecutive diabetic patients without (NDR) or with diabetic retinopathy (non-proliferative diabetic retinopathy [NPDR] and no clinically significant macular edema [CSME-]; NDPR and clinically significant macular edema [CSME+]) underwent EDI OCT. Twenty-one age and sex matched healthy subjects (21 eyes) also underwent EDI OCT. Results: A total of 63 eyes of 63 consecutive diabetic patients (26 female (41.2%); mean age 65±9 years, range 48-83 years) were included in the analysis. Mean ...

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    13. Comparison of Two Spectral Domain Optical Coherence Tomography Devices for Angle-Closure Assessment

      Comparison of Two Spectral Domain Optical Coherence Tomography Devices for Angle-Closure Assessment

      Purpose. To compare two spectral domain optical coherence tomography (SD-OCT) devices for the identification of angle structures and the presence of angle closure. Methods. This was a prospective comparative study. Consecutive patients underwent gonioscopy and anterior segment imaging using two SD-OCT devices (iVue and Cirrus). Images were evaluated for the ability to detect angle structures such as Schwalbe's line (SL), trabecular meshwork (TM), Schlemm's canal (SC), and scleral spur (SS), and the presence of angle closure. Angle closure was defined as iris contact with the angle wall anterior to the SS on SD-OCT, and nonvisibility of the posterior ...

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    14. Effect Of Angle Of Incidence On Macular Thickness And Volume Measurements Obtained By Spectral-Domain Optical Coherence Tomography

      Effect Of Angle Of Incidence On Macular Thickness And Volume Measurements Obtained By Spectral-Domain Optical Coherence Tomography

      Purpose:To evaluate the effect of angle of incidence on macular thickness and volume measurements obtained by spectral-domain optical coherence tomography (SDOCT) Methods: 30 eyes from 15 healthy young subjects underwent macular cube volume scans (512 x 128 protocol) following dilation using the Cirrus SDOCT. Scans were obtained by positioning the scanning beam in the center of the dilated pupil, as well as in four eccentric positions (approximately 3 mm from the center), superior, inferior, nasal, and temporal, For creating oblique angles of incidence between the light beam and the retina. In all cases, the region scanned by the volume ...

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    15. Behaviour of SD-OCT detected hyperreflective foci in the retina of Anti-VEGF treated patients with Diabetic Macular Edema

      Behaviour of SD-OCT detected hyperreflective foci in the retina of Anti-VEGF treated patients with Diabetic Macular Edema

      Purpose:Hyperreflective foci (HF) are observable within the neurosensory retina in diabetic macular edema (DME) using spectral domain optical coherence tomography (SD-OCT). The HF behaviour was evaluated during Anti-VEGF therapy in DME. Methods: Fifty-one patients (mean age: 67 years) underwent SD-OCT (Heidelberg engineering, Germany) before and one month after one Anti-VEGF injection (Ranibizumab: n=30; Bevacizumab: n=21). The amount of HFs were semi-quantitatively counted, assigned to 3 groups (A: SDPs n=1-10; B: n=11-20; C: n>20) and correlated to the course of visual acuity and foveal thickness (paired t-test). Additionally the baseline HbA1c was categorized and correlated ...

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    16. Determinants of Ganglion Cell-Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Determinants of Ganglion Cell-Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Purpose. To determine the distribution, variation and determinants of ganglion cell-inner plexiform layer (GC-IPL) thickness in non-glaucomatous eyes measured by high-definition optical coherence tomography (HD-OCT). Methods. 623 Chinese adults aged 40-80 years were consecutively recruited from a population-based study. All subjects underwent a standardized interview, ophthalmic examination and automated perimetry. HD-OCT (Cirrus, software version 6.0, Carl Zeiss Meditec, Dublin, CA) with macular cube protocol was used to measure the GC-IPL thickness. Univariate and multiple linear regression analyses were performed to examine the relationship between GC-IPL thickness with ocular and systemic factors. Results. The mean (± SD) age of study subjects ...

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    17. Laminar Displacement and Prelaminar Tissue Thickness Change after Glaucoma Surgery Imaged with Optical Coherence Tomography

      Laminar Displacement and Prelaminar Tissue Thickness Change after Glaucoma Surgery Imaged with Optical Coherence Tomography

      Purpose: To study changes in lamina cribrosa position and prelaminar tissue thickness (PTT) after surgical intraocular pressure (IOP) reduction in glaucoma patients. Methods: Twenty-two patients (mean age, 71.4 years) were imaged with spectral domain optical coherence tomography (SD-OCT, 24 radial B-scans centered on the optic nerve head) before trabeculectomy or tube shunt implantation. Follow-up images were acquired 1 week, 1 month, 3 and 6 months post-surgery. Bruch's membrane opening (BMO), the internal limiting membrane (ILM) and the anterior laminar surface (ALS) were segmented with custom software. Surfaces were fitted to the ILM and ALS with the extracted 3D ...

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    18. A Novel Technique of Adjusting Segmentation Boundary Layers to Achieve Comparability of Retinal Thickness and Volumes between Spectral Domain and Time Domain OCT

      A Novel Technique of Adjusting Segmentation Boundary Layers to Achieve Comparability of Retinal Thickness and Volumes between Spectral Domain and Time Domain OCT

      Purpose: The quantitative assessment of retinal thickness and volume varies according to the Optical Coherence Tomography (OCT) machine used due to differences in segmentation lines. We describe a novel method of adjusting the segmentation lines of spectral-domain OCT (SD-OCT) to enable comparison with time-domain OCT (TD-OCT), and assess factors affecting its accuracy. Methods: In a prospective study, SD-OCT (Spectralis OCT) and TD-OCT (Stratus OCT) were sequentially performed on 200 eyes of 100 healthy individuals. Central retinal thickness (CRT), central point thickness (CPT) and 1mm volume of the ETDRS grid were compared between the 2 machines. The segmentation lines on SD-OCT ...

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    19. Comparison of two spectral domain optical coherence tomography devices for angle closure assessment

      Comparison of two spectral domain optical coherence tomography devices for angle closure assessment

      Purpose. To compare two spectral domain optical coherence tomography (SD-OCT) devices for the identification of angle structures and the presence of angle closure Methods. This was a prospective comparative study. Consecutive patients underwent gonioscopy and anterior segment imaging using 2 SD-OCT devices (iVue [Optovue Corporation, Fremont, Ca] and Cirrus [Carl Zeiss Meditec, Dublin, Ca]). Images were evaluated for the ability to detect angle structures such as Schwalbe's line (SL), trabecular meshwork (TM), Schlemm's canal (SC), and scleral spur (SS); and the presence of angle closure. Angle closure was defined as iris contact with the angle wall anterior to ...

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    20. Quantifying Structures in the Ocular Fundus

      Quantifying Structures in the Ocular Fundus

      Moghimi et al. showed that Heidelberg retinal tomography (HRT) and one brand of spectral domain optical coherence tomography (SD-OCT) do not give the same measurement of disc and neuro-retinal rim areas within the disc (http://dx.doi.org/10.1167/iovs.11-8362).1 The measurements correspond better with an attempt to correct for optical magnification (by taking into account axial length of the eye). However, the definition of “the edge of the disc,” which enters into calculations of the disc area and rim area, is not the same for these two instruments. It often is a boundary defined as the ...

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    21. Reproducibility of Macular, Retinal Nerve Fiber Layer, and ONH Measurements by OCT in Rhesus Monkeys: The Beijing Intracranial and Intraocular Pressure (iCOP) Study

      Reproducibility of Macular, Retinal Nerve Fiber Layer, and ONH Measurements by OCT in Rhesus Monkeys: The Beijing Intracranial and Intraocular Pressure (iCOP) Study

      Purpose. We evaluated repeatability and reproducibility of measurements of the retinal nerve fiber layer thickness (RNFLT), optic nerve head (ONH), and macular inner retinal layer (MIRL) by RTVue spectral-domain optical coherence tomography (OCT) in normal Rhesus monkeys. Methods. The experimental study included 15 adult Rhesus macaque monkeys. RNFLT, ONH parameters (area of disc, cup, and rim; volume of cup and rim; and cup-to-disc ratios), and MIRL thickness were imaged at three separate examinations within one month. Each eye was imaged three times at the first examination, and once at each of the two following examinations. We determined the intra-session and ...

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    22. Patterns of Ganglion Cell Complex and Nerve Fiber Layer Loss in Nonarteritic Ischemic Optic Neuropathy by Fourier-Domain Optical Coherence Tomography

      Patterns of Ganglion Cell Complex and Nerve Fiber Layer Loss in Nonarteritic Ischemic Optic Neuropathy by Fourier-Domain Optical Coherence Tomography

      Purpose. To characterize by Fourier-domain optical coherence tomography (FD-OCT) the loss of nerve fiber layer (NFL) and ganglion cell complex (GCC) in nonarteritic ischemic optic neuropathy (NAION). Methods. Patients diagnosed with NAION were enrolled and categorized into “superior field loss (SFL),” “inferior field loss (IFL),” and “bihemispheric field loss (BFL)” groups based on the Swedish interactive threshold algorithm 30‐2 achromatic visual field (VF) tests. Six months after presentation, they were scanned by FD-OCT to map peripapillary NFL and macular GCC thicknesses. Age-matched normals were selected from participants in the Advanced Imaging for Glaucoma Study (www.AIGStudy.net). Deviation maps ...

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    23. Assessment of Macular Function for Idiopathic Epiretinal Membranes Classified by Spectral-Domain Optical Coherence Tomography

      Assessment of Macular Function for Idiopathic Epiretinal Membranes Classified by Spectral-Domain Optical Coherence Tomography

      Purpose. To evaluate the functional changes in various morphologic types of idiopathic epiretinal membrane (ERM) by multifocal electroretinography (mfERG) and spectral-domain optical coherence tomography (SD-OCT). Methods. All patients (n = 71) with unilateral idiopathic ERM underwent complete ophthalmologic examination, including measurements of best-corrected visual acuity (BCVA), SD-OCT, and mfERG for both eyes. To classify idiopathic ERM by subtype, the morphologic characteristics of the foveal area on representative scanned images were assessed. The five subtypes by foveal SD-OCT morphology included fovea-attached ERM with outer retinal thickening and minimal inner retinal change (Group 1A), outer retinal inward projection and inner retinal thickening (Group ...

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    24. Does optic nerve head size variation affect circumpapillary retinal nerve fiber layer thickness measurement by optical coherence tomography?

      Does optic nerve head size variation affect circumpapillary retinal nerve fiber layer thickness measurement by optical coherence tomography?

      Purpose: To determine the relationship between retinal nerve fiber layer (RNFL) thickness, optic disc size and image magnification. Methods: The cohort consisted of 196 normal eyes of 101 participants in the Advanced Imaging for Glaucoma Study (AIGS), a multi-center, prospective, longitudinal study to develop advanced imaging technologies for glaucoma diagnosis. Scanning laser tomography (HRT II) was used to measure disc size. Optical coherence tomography (Stratus) was used to perform circumpapillary RNFL thickness measurements using the standard fixed 3.46 mm nominal scan diameter. A theoretical model of magnification effects was developed to relate RNFL thickness (overall average) with axial length ...

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