1. Articles in category: Ophthalmology

    553-576 of 6095 « 1 2 ... 21 22 23 24 25 26 27 ... 252 253 254 »
    1. Improving the cost-effectiveness of photographic screening for diabetic macular oedema: a prospective, multi-centre, UK study

      Improving the cost-effectiveness of photographic screening for diabetic macular oedema: a prospective, multi-centre, UK study

      Background/aims Retinal screening programmes in England and Scotland have similar photographic grading schemes for background (non-proliferative) and proliferative diabetic retinopathy, but diverge over maculopathy. We looked for the most cost-effective method of identifying diabetic macular oedema from retinal photographs including the role of automated grading and optical coherence tomography, a technology that directly visualises oedema. Methods Patients from seven UK centres were recruited. The following features in at least one eye were required for enrolment: microaneurysms/dot haemorrhages or blot haemorrhages within one disc diameter, or exudates within one or two disc diameters of the centre of the macula ...

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    2. Quantitative Optical Coherence Tomography Angiography of Choroidal Neovascularization in Age-related Macular Degeneration

      Quantitative Optical Coherence Tomography Angiography of Choroidal Neovascularization in Age-related Macular Degeneration

      Purpose To detect and quantify choroidal neovascularization (CNV) in patients with age-related macular degeneration (AMD) using optical coherence tomography (OCT) angiography. Design Observational, cross-sectional study. Participants A total of 5 normal subjects and 5 subjects with neovascular AMD were included. Methods A total of 5 eyes with neovascular AMD and 5 normal age-matched controls were scanned by a high-speed (100 000 A-scans/seconds) 1050-nm wavelength swept-source OCT. The macular angiography scan covered a 3×3-mm area and comprised 200×200×8 A-scans acquired in 3.5 seconds. Flow was detected using the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm. Motion artifacts were ...

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    3. Evidence of early ultrastructural photoreceptor abnormalities in light-induced retinal degeneration using spectral domain optical coherence tomography

      Evidence of early ultrastructural photoreceptor abnormalities in light-induced retinal degeneration using spectral domain optical coherence tomography

      Background To study spatiotemporal in vivo changes in retinal morphology and quantify thickness of retinal layers in a mouse model of light-induced retinal degeneration using spectral domain optical coherence tomography (SD-OCT). Methods BALB/c mice were exposed to 5000 lux of constant light for 3 h. SD-OCT images were taken 3 h, 24 h, 3 days, 1 week and 1 month after light exposure and were compared with histology at the same time points. SD-OCT images were also taken at 0, 1 and 2 h after light exposure in order to analyse retinal changes at the earliest time points. The ...

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    4. Circumpapillary Choroidal Hemorrhage Masquerading As Melanoma—Enhanced Depth Imaging Optical Coherence Tomography Features

      Circumpapillary Choroidal Hemorrhage Masquerading As Melanoma—Enhanced Depth Imaging Optical Coherence Tomography Features

      Purpose: To illustrate the distinguishing findings of choroidal hemorrhage on enhanced depth imaging optical coherence tomography. Methods: Case report. Results: An 81-year-old man on a daily aspirin with well-controlled hypertension noted blurred visual acuity and was diagnosed with presumed choroidal melanoma based on the clinical appearance and generalized hyperfluorescence on angiography. Upon referral, visual acuity was 20/100 in the right eye and 20/30 in the otherwise unremarkable left eye. Clinical examination revealed a choroidal mass of velvety-brown color with ill-defined margins, suggestive of hemorrhage. Ultrasonography disclosed a thin echogenic mass of 2.1 mm in thickness. Fluorescein angiography ...

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    5. Optical system with multiple scanners for ophthalmic surgical laser

      Optical system with multiple scanners for ophthalmic surgical laser

      An ophthalmic surgical laser system includes a laser engine, to generate a laser beam, a first Z scanner, to receive the generated laser beam, and to scan a focal spot of the laser system over a first Z interval along an optical axis of the laser system an XY scanner, to receive the laser beam output by the first Z scanner, and to scan the focal spot of the laser system in a direction essentially transverse to the optical axis of the laser system, and a second Z scanner, to receive the scanned laser beam from the XY scanner, and ...

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      Mentions: LenSx
    6. Patency of small laser iridotomy evaluated using anterior-segment optical coherence tomography

      Patency of small laser iridotomy evaluated using anterior-segment optical coherence tomography

      We report the case of a patient with recurrent acute angle-closure glaucoma who had undergone a previous laser iridotomy. Because the initial iridotomy was small, patency could not be determined by slit-lamp examination. Therefore, anterior-segment optical coherence tomography was used to evaluate the patency. Cross-sectional images showed the presence of a membrane with an anterior bowing configuration at the base of the iridotomy, suggesting that recurrent pupillary block was the causative mechanism. A repeat laser iridotomy was performed, with a resultant decrease in the intraocular pressure and widening of the anterior chamber angle. Anterior-segment optical coherence tomography may be helpful ...

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    7. A Pilot Quantitative Study of Topographic Correlation between Reticular Pseudodrusen and the Choroidal Vasculature Using En Face Optical Coherence Tomography

      A Pilot Quantitative Study of Topographic Correlation between Reticular Pseudodrusen and the Choroidal Vasculature Using En Face Optical Coherence Tomography

      Purpose To analyze the topographic correlation between reticular pseudodrusen (RPD) visualized on infrared reflectance (IR) and choroidal vasculature using en-face volumetric spectral-domain optical coherence tomography (SD-OCT). Methods A masked observer marked individual RPD on IR images using ImageJ (NIH, Bethesda, MD). Using the macular volume scan (Cirrus, Carl Zeiss Meditec Inc, Dublin, CA), the RPE slab function was used to generate a C-scan of the most superficial choroidal vasculature. An independent masked grader created a topographic binary map of the choroidal vasculature by thresholding the en-face image, which was overlaid onto the IR map of RPD. For each IR image ...

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    8. Swept-source optical coherence tomography imaging of the cortical vitreous and the vitreoretinal interface in proliferative diabetic retinopathy: assessment of vitreoschisis, neovascularisation and the internal limiting membrane

      Swept-source optical coherence tomography imaging of the cortical vitreous and the vitreoretinal interface in proliferative diabetic retinopathy: assessment of vitreoschisis, neovascularisation and the internal limiting membrane

      Anomalous posterior vitreous detachment leads to shrinkage of the inner vitreous with the outer precortical vitreous cortex remaining attached to the macula and retina, resulting in vitreoschisis. 1 Sebag and coworkers have reported vitreoschisis in macular disorders, and vitreoschisis has been demonstrated using ultrasonography and histopathology. 2–4 Swept-source OCT (SS-OCT) is a new imaging technology (Atlantis DRI-OCT-1, Topcon, Japan). We demonstrate for the first time in vivo the microstructural tomographic features of and spatial vitreoretinal relationships between vitreoschisis, retinal and optic nerve head neovascularisation, detachment of the internal limiting membrane (ILM) and traction on the neuroretina in proliferative diabetic ...

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    9. 3D graph-based automated segmentation of corneal layers in anterior-segment optical coherence tomography images of mice

      3D graph-based automated segmentation of corneal layers in anterior-segment optical coherence tomography images of mice

      Anterior segment optical coherence tomography (AS-OCT) is a non-invasive imaging modality that allows for the quantitative assessment of corneal thicknesses. Automated approaches for these measurements are not readily available and therefore measurements are often obtained manually. While graph-based approaches that enable the optimal simultaneous segmentation of multiple 3D surfaces have been proposed and applied to 3D optical coherence tomography volumes of the back of the eye, such approaches have not been applied for the segmentation of the corneal surfaces. In this work we propose adapting this graph-based method for the automated 3D segmentation of three corneal surfaces in AS-OCT images ...

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    10. Groundbreaking Zeiss Kit Used in First Eye Surgeries

      Groundbreaking Zeiss Kit Used in First Eye Surgeries

      Combination of optical coherence tomography with surgical microscope gives surgeons 'unprecedented' views. Combination kit used in live surgery A new kind of surgical microscope from Zeiss that features integrated intra-operative optical coherence tomography (OCT) is now being used by ophthalmic surgeons. Said to provide those surgeons with unprecedented views of transparent ocular structures during operations, the visualization tool combines two “gold standard” techniques into a single system for the first time. According to the Germany-based optics and optical technology giant's Meditec subsidiary, as well as being able to see transparent structures of the eye during surgery, surgeons can also ...

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    11. Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT

      Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT

      AIM: To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography (OCT). METHODS: Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length:low and medium myopia group (LMMG), high myopia group (HMG) and super high myopia group (SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness, central subfield thickness, inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson ...

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    12. Morphological Characteristics of Macular Complications of a Dome-Shaped Macula Determined by Swept-Source Optical Coherence Tomography

      Morphological Characteristics of Macular Complications of a Dome-Shaped Macula Determined by Swept-Source Optical Coherence Tomography

      Purpose To investigate the morphological characteristics of macular complications of dome-shaped maculas using Swept-Source Optical Coherence Tomography (OCT). Design Retrospective observational case series. Methods Axial length measurements and Swept-Source OCT were performed in 49 highly myopic eyes (in five males and 30 females) with dome-shaped maculas. We classified the dome patterns and measured the central retinal thickness, central choroidal thickness, central scleral thickness and the macular bulge height, and assessed the associations of these parameters with macular complications. Results The central scleral thickness was significantly negatively correlated with age and the axial length. We classified the eyes into three groups ...

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    13. Ocular fundus reference images from optical coherence tomography

      Ocular fundus reference images from optical coherence tomography

      Two-dimensional images computed from three-dimensional optical coherence tomography (OCT) data are intrinsically aligned with it, allowing to accurately position a retinal OCT scan within the ocular fundus. In this work, we aim to compute an OCT fundus reference image with improved retinal vasculature extension and contrast over traditional approaches. Based on the shadow casted by hemoglobin on the outer layers of the retina, we compute three independent images from the OCT volumetric data (including the traditional fundus reference image). Combining these images, a fourth one is created that is able to outperform the other three, both quantitatively and qualitatively (as ...

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    14. Monitoring Keratitis Resolution with Optical Coherence Tomography

      Monitoring Keratitis Resolution with Optical Coherence Tomography

      Purpose: Biomicroscopy is generally used, sometimes in conjunction with photography or ultrasound pachymetry, to monitor conditions involving stromal keratitis and edema. Spectral-domain optical coherence tomography (SD-OCT), a technology typically used to examine the posterior segment, may be useful in monitoring the therapeutic interventions for conditions involving corneal edema such as disciform keratitis. Case Reports: Two cases of disciform keratitis were followed to resolution using SD-OCT with anterior segment imaging software (Cirrus 4000; Carl Zeiss Meditec, Dublin, CA) to quantify decreasing edema throughout treatment. The thickest area of the cornea was located and measured across time using SD-OCT until resolution was ...

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    15. Corneal stroma demarcation line after standard and high-intensity collagen crosslinking determined with anterior segment optical coherence tomography

      Corneal stroma demarcation line after standard and high-intensity collagen crosslinking determined with anterior segment optical coherence tomography

      Purpose To use anterior segment optical coherence tomography (AS-OCT) to compare corneal stroma demarcation line depth after corneal collagen crosslinking (CXL) with 2 treatment protocols. Setting Vardinoyiannion Eye Institute of Crete, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. Design Prospective comparative interventional case series. Methods Corneal collagen crosslinking was performed in all eyes using the same ultraviolet-A (UVA) irradiation device (CCL-365). Eyes were treated for 30 minutes with 3 mW/cm 2 according to the standard Dresden protocol (Group 1) or for 10 minutes with 9 mW/cm 2 of UVA irradiation intensity (Group 2). One month postoperatively ...

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    16. Spectral-domain optical coherence tomography evaluation of choroidal melanoma and nevus fine-needle aspiration biopsy incision sites

      Spectral-domain optical coherence tomography evaluation of choroidal melanoma and nevus fine-needle aspiration biopsy incision sites

      The authors present three cases in which spectral-domain optical coherence tomography was used to identify fine-needle aspiration biopsy incision sites. These biopsies were performed to obtain tissue for gene expression profiling of choroidal tumors. A transvitreal route into the apex of the tumors was utilized for the biopsies while the patients underwent pars plana vitrectomy, membrane peel, laser ablation, phacoemulsification with posterior chamber intraocular lens implantation, and intravitreal triamcinolone acetonide. To the best of the authors’ knowledge, this is the first report documenting fine-needle aspiration biopsy incision wound architecture of the posterior segment with optical coherence tomography.

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    17. Efficacy of Intraoperative Anterior Segment Optical Coherence Tomography during Descemet's Stripping Automated Endothelial Keratoplasty

      Efficacy of Intraoperative Anterior Segment Optical Coherence Tomography during Descemet's Stripping Automated Endothelial Keratoplasty

      Purpose . To examine the graft-host interface during Descemet's stripping automated endothelial keratoplasty (DSAEK) surgery with optical coherence tomography (OCT). Design . Prospective, interventional case series. Patients and Methods . Eight patients who underwent a DSAEK were included. A handheld OCT was used intraoperatively to examine the presence of interface fluid between the host cornea and the graft. Results . In 3 patients, no interface fluid was detected between the host cornea and the graft after the graft was attached by air injection. In 4 patients, interface fluid was detected after the graft was attached by air injection. The remaining interface fluid was ...

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    18. Spectral-domain optical coherence tomography imaging of macula-off rhegmatogenous retinal detachment

      Spectral-domain optical coherence tomography imaging of macula-off rhegmatogenous retinal detachment

      The timing of repair and the utility of spectral-domain optical coherence tomography (SD-OCT) for macula-off retinal detachment remains a controversial issue. Four patients who presented with macula-off retinal detachment underwent repair at various time points after symptom onset. Postoperative SD-OCT of the macula demonstrated correlation with final visual acuity

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    19. Anatomic vs. Acquired Image Frame Discordance in Spectral Domain Optical Coherence Tomography Minimum Rim Measurements

      Anatomic vs. Acquired Image Frame Discordance in Spectral Domain Optical Coherence Tomography Minimum Rim Measurements

      Purpose To quantify the effects of using the fovea to Bruch's membrane opening (FoBMO) axis as the nasal-temporal midline for 30° sectoral (clock-hour) spectral domain optical coherence tomography (SDOCT) optic nerve head (ONH) minimum rim width (MRW) and area (MRA) calculations. Methods The internal limiting membrane and BMO were delineated within 24 radial ONH B-scans in 222 eyes of 222 participants with ocular hypertension and glaucoma. For each eye the fovea was marked within the infrared reflectance image, the FoBMO angle (θ) relative to the acquired image frame (AIF) horizontal was calculated, the ONH was divided into 30°sectors using ...

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    20. Optical quality assessment in normal and forme fruste keratoconus eyes with a double-pass system: a comparison and variability study

      Optical quality assessment in normal and forme fruste keratoconus eyes with a double-pass system: a comparison and variability study

      Purpose To comparatively evaluate the image quality in normal and forme fruste keratoconus patients using a double-pass system. Methods Fourteen normal eyes and 15 eyes with forme fruste keratoconus were included. Corneal tomographic parameters were obtained with optical coherence tomography. Image quality characteristics were determined by an optical quality analysis system (OQAS). Two readings were obtained from each eye. The following parameters were analysed: modulation transfer function cutoff frequency (MTF), Strehl ratio and OQAS values (OV) at contrasts of 100% (OV-100), 20% (OV-20) and 9% (OV-9). Repeatability coefficient (RC), coefficient of variation (CVw) and intraclass correlation coefficient (ICC) were evaluated ...

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    21. Optical Coherence Tomography Shape Analysis of the Peripapillary Retinal Pigment Epithelium Layer in Presumed Optic Nerve Sheath Meningiomas

      Optical Coherence Tomography Shape Analysis of the Peripapillary Retinal Pigment Epithelium Layer in Presumed Optic Nerve Sheath Meningiomas

      Background: Geometric morphometrics (GM) was used to compare the shape of the peripapillary retinal pigment epithelium-Bruch's membrane (ppRPE) layer imaged on spectral domain optical coherence tomography (SD-OCT) of patients with presumed optic nerve sheath meningiomas (pONSM) and normal subjects. Methods: We compared 2 groups: 30 normals to 10 patients (11 eyes) with pONSM. We digitized 20 equidistant semi-landmarks on OCT images of the ppRPE-layer, spanning 2500 [mu]m on each side of the neural canal opening (NCO). Data were analyzed using standard GM techniques including a generalized least squares Procrustes superimposition, principal component analysis (PCA), thin-plate spline, and permutation ...

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    22. Towards a comprehensive eye model for zebrafish retinal imaging using full range spectral domain optical coherence tomography

      Towards a comprehensive eye model for zebrafish retinal imaging using full range spectral domain optical coherence tomography

      In regenerative medicine, the zebrafish is a prominent animal model for studying degeneration and regeneration processes, e.g. of photoreceptor cells in the retina. By means of optical coherence tomography (OCT), these studies can be conducted over weeks using the same individual and hence reducing the variability of the results. To allow an improvement of zebrafish retinal OCT imaging by suitable optics, we developed a zebrafish eye model using geometrical data obtained by in vivo dispersion encoded full range OCT as well as a dispersion comprising gradient index (GRIN) lens model based on refractive index data found in the literature ...

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    23. Reliability and validity of Cirrus and Spectralis optical coherence tomography for detecting retinal atrophy in Alzheimer’s disease

      Reliability and validity of Cirrus and Spectralis optical coherence tomography for detecting retinal atrophy in Alzheimer’s disease

      Background To evaluate and compare the ability of two Fourier-domain optical coherence tomography (OCT) devices to detect retinal and retinal nerve fibre layer (RNFL) atrophy in patients with Alzheimer’s disease (AD) compared with healthy subjects; to test the intra-session reliability of two OCT devices in AD patients and healthy subjects. Methods AD patients (n = 75) and age-matched healthy subjects (n = 75) underwent three Macular Cube 200 × 200 protocols using the Cirrus and Spectralis OCT devices and three 360° circular scans centred on the optic disc using the Cirrus OCT device, the classic glaucoma application, and the new Nsite Axonal ...

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