1. Articles in category: Ophthalmology

    1-24 of 6246 1 2 3 4 ... 259 260 261 »
    1. Choroidal thickness measurement by enhanced depth imaging and swept-source optical coherence tomography in central serous chorioretinopathy

      Choroidal thickness measurement by enhanced depth imaging and swept-source optical coherence tomography in central serous chorioretinopathy

      Background We evaluated subfoveal choroidal thickness measured with two different forms of optical coherence tomography (OCT), enhanced-depth imaging (EDI) and swept-source (SS) OCT, in central serous chorioretinopathy (CSC). Methods Fifty-six eyes of 48 patients diagnosed with acute or chronic CSC, were studied prospectively. Subfoveal choroidal thickness was measured as the distance between the outer border of the retinal pigment epithelium-Bruch's membrane complex, and the chorioscleral border under the fovea. Subfoveal choroidal thickness was measured using EDI-OCT and SS-OCT. We also measured serous retinal detachment (SRD) only with SS-OCT. The Pearson correlation coefficient was used to assess the correlation between ...

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    2. Application of anterior segment optical coherence tomography to identify eyes with posterior polar cataract at high risk for posterior capsule rupture

      Application of anterior segment optical coherence tomography to identify eyes with posterior polar cataract at high risk for posterior capsule rupture

      Purpose To use anterior segment optical coherence tomography (AS-OCT) to identify eyes with posterior polar cataract at high risk for posterior capsule rupture (PCR) during cataract extraction. Setting Hong Kong Eye Hospital, Hong Kong, China. Design Retrospective case series. Methods Eyes with clinically diagnosed posterior polar cataract that had AS-OCT imaging and phacoemulsification were included. Each eye was graded according to the features of the posterior lens opacity and the underlying capsule. Eyes were categorized as having grade 1 or grade 2 cataract depending on the amount of clearance between the posterior opacity and the capsule (≥50% clearance and <50 ...

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    3. Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

      Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

      To extend our understanding of tear film dynamics for the management of dry eye disease, we propose a method to optically sense the tear film and estimate simultaneously the thicknesses of the lipid and aqueous layers. The proposed method, SDT-OCT, combines ultra-high axial resolution optical coherence tomography (OCT) and a robust estimator based on statistical decision theory (SDT) to achieve thickness measurements at the nanometer scale. Unlike conventional Fourier-domain OCT where peak detection of layers occurs in Fourier space, in SDT-OCT thickness is estimated using statistical decision theory directly on the raw spectra acquired with the OCT system. In this ...

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    4. SPARSE AND LOW RANK DECOMPOSITION BASED BATCH IMAGE ALIGNMENT FOR SPECKLE REDUCTION OF RETINAL OCT IMAGES

      SPARSE AND LOW RANK DECOMPOSITION BASED BATCH IMAGE ALIGNMENT FOR SPECKLE REDUCTION OF RETINAL OCT IMAGES

      Optical Coherence Tomography (OCT) in an emerging technique in the field of biomedical imaging, with applications in ophthalmology, dermatology, coronary imaging etc. Due to the underlying physics, OCT images usually suffer from a granular pattern, called speckle noise, which restricts the process of interpretation. Here, a sparse and low rank decomposition based method is used for speckle reduction in retinal OCT images. In this technique, at first, several OCT images of the same location (to some extent) are acquired and stacked together. The next step is the batch alignment of the images using a sparse and low-rank decomposition based technique ...

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    5. Evaluation of Corneal Stromal Demarcation Line after Two Different Protocols of Accelerated Corneal Collagen Cross-Linking Procedures Using Anterior Segment Optical Coherence Tomography and Confocal Microscopy

      Evaluation of Corneal Stromal Demarcation Line after Two Different Protocols of Accelerated Corneal Collagen Cross-Linking Procedures Using Anterior Segment Optical Coherence Tomography and Confocal Microscopy

      Purpose . To evaluate the depth of corneal stromal demarcation line using AS-OCT and confocal microscopy after two different protocols of accelerated corneal collagen cross-linking procedures (CXL). Methods . Patients with keratoconus were divided into two groups. Peschke CXL device (Peschke CCL-VARIO Meditrade GmbH) applied UVA light with an intended irradiance of 18.0 mW/cm 2 for 5 minutes after applying riboflavin for 20 minutes (group 1) and 30 minutes (group 2). One month postoperatively, corneal stromal demarcation line was measured using AS-OCT and confocal microscopy. Results . This study enrolled 34 eyes of 34 patients (17 eyes in group 1 and ...

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    6. Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking

      Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking

      Purpose . To compare the penetration of riboflavin using a microscope-integrated real time spectral domain optical coherence tomography (ZEISS OPMI LUMERA 700 and ZEISS RESCAN 700) in keratoconus patients undergoing accelerated collagen crosslinking (ACXL) between epithelium on (epi-on) and epithelium off (epi-off). Methods . Intraoperative images were obtained during each of the procedures. Seven keratoconus patients underwent epi-on ACXL and four underwent epi-off ACXL. A software tool was developed using Microsoft.NET and Open Computer Vision (OpenCV) libraries for image analysis. Pre- and postprocedure images were analyzed for changes in the corneal hyperreflectance pattern as a measure of the depth of riboflavin ...

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    7. Longitudinal Analysis of Reticular Drusen Associated with Age-Related Macular Degeneration Using Combined Confocal Scanning Laser Ophthalmoscopy and Spectral-Domain Optical Coherence Tomography Imaging

      Longitudinal Analysis of Reticular Drusen Associated with Age-Related Macular Degeneration Using Combined Confocal Scanning Laser Ophthalmoscopy and Spectral-Domain Optical Coherence Tomography Imaging

      Purpose: To evaluate longitudinal variations of reticular drusen (RDR) in age-related macular degeneration using confocal scanning laser ophthalmoscopy (cSLO), near-infrared reflectance (NIR) and spectral-domain optical coherence tomography (SD-OCT) imaging. Methods: Eighteen eyes of 12 patients with RDR (median observational time 5 months, range 3-10) were included. Changes over time in the en face cSLO NIR images, the identical SD-OCT B scan (simple approach) and the dense SD-OCT volume scans (11 µm between B scans, detailed approach) for 5 preselected RDR lesions were analysed, respectively. Results: Nineteen of 90 (21%) lesions were no longer detectable at the follow-up examination with the ...

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    8. 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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    9. 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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    10. 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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    11. International crew set for launch to space station Sunday

      International crew set for launch to space station Sunday

      “Now we’re finding that 60 percent of long duration fliers have vision (problems) and some of those don’t correct, I mean they can still see, but you have degraded vision,” he said. “So one of the main experiments I’m doing is going to be a pretty comprehensive study of vision. I’ll be doing ultrasound on my eyes, an OCT scan (optical coherence tomography), a fundascope, several different cameras looking inside the eye, some ultrasound of my brain and heart and pressure and blood flow into the eye. “So there’s a very intense focus on that ...

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    12. Diagnostic accuracy of the parameters from ganglion cell complex map, evaluated with SD-OCT in primary open-angle glaucoma

      Diagnostic accuracy of the parameters from ganglion cell  complex map, evaluated with SD-OCT in primary open-angle  glaucoma

      Purpose: To evaluate the sensitivity and specificity of ganglion cell complex (GCC) parameters, obtained with optical coherence tomography (OCT) and to determine their role in diagnosis of primary open-angle glaucoma patients. Materials and methods: The study included 84 eyes of patients with primary open-angle glaucoma (POAG) and 40 eyes of healthy individuals. All of them underwent complete eye examination, including standard automated perimetry (HFA II) and OCT (RTVue-100). Avg. GCC (average GCC), Sup. GCC (superior GCC), Inf. GCC (inferior GCC), GLV (globаl loss volume), FLV (focal loss volume) and RNFL (retinal nerve fiber layer — ONH map) were measured. ROC curves ...

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    13. Intraocular optical coherence tomography

      Intraocular optical coherence tomography

      Since its introduction as a diagnostic instrument, optical coherence tomography (OCT) has become an essential instrument for ophthalmologists as it offers accurate details on both the vitreoretinal interface and the retinal layers. Initially designed as a pre- and post-operative instrument, today we are attending to its introduction as an intraoperative tool. Inspired by the intravascular use of the OCT, we developed a prototype spectral domain OCT probe for intraocular use. It is therefore possible to make dynamic real-time scans from the vitreous and retina at the posterior pole and in the peripheral retina. This type of endo-OCT may therefore help ...

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    14. Application of Improved Homogeneity Similarity-Based Denoising in Optical Coherence Tomography Retinal Images

      Application of Improved Homogeneity Similarity-Based Denoising in Optical Coherence Tomography Retinal Images

      Image denoising is a fundamental preprocessing step of image processing in many applications developed for optical coherence tomography (OCT) retinal imaging—a high-resolution modality for evaluating disease in the eye. To make a homogeneity similarity-based image denoising method more suitable for OCT image removal, we improve it by considering the noise and retinal characteristics of OCT images in two respects: (1) median filtering preprocessing is used to make the noise distribution of OCT images more suitable for patch-based methods; (2) a rectangle neighborhood and region restriction are adopted to accommodate the horizontal stretching of retinal structures when observed in OCT ...

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    15. Optical coherence tomography shows early loss of the inferior temporal quadrant retinal nerve fiber layer in autosomal dominant optic atrophy

      Optical coherence tomography shows early loss of the inferior temporal quadrant retinal nerve fiber layer in autosomal dominant optic atrophy

      Purpose The aim of the study was to evaluate the relationship between visual function and retinal nerve fiber layer thickness (RNFLT) determined using Stratus optical coherence tomography (OCT) in patients with autosomal dominant optic atrophy (ADOA). Methods The study was a retrospective, institutional, and comparative case series. Thirty-six consecutive patients with ADOA and 72 age-matched normal controls were compared with regard to RNFLT, best-corrected visual acuity (BCVA), and visual field. Results The relative reduction of RNFLT of ADOA patients was most evident in the temporal quadrant (56.8 %), followed by the inferior (35.5 %), superior (27.2 %), and nasal quadrants ...

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    16. Applications of visual evoked potentials and Fourier-domain optical coherence tomography in Parkinson's disease: a controlled study

      Applications of visual evoked potentials and Fourier-domain optical coherence tomography in Parkinson's disease: a controlled study

      Purpose: The goal of this cross-sectional observational study was to quantify the pattern-shift visual evoked potentials (VEP) and the thickness as well as the volume of retinal layers using optical coherence tomography (OCT) across a cohort of Parkinson's disease (PD) patients and age-matched controls. Methods: Forty-three PD patients and 38 controls were enrolled. All participants underwent a detailed neurological and ophthalmologic evaluation. Idiopathic PD cases were included. Cases with glaucoma or increased intra-ocular pressure were excluded. Patients were assessed by VEP and high-resolution Fourier-domain OCT, which quantified the inner and outer thicknesses of the retinal layers. VEP latencies and ...

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    17. Assessment of Corneal Epithelial Thickness in Dry Eye Patients

      Assessment of Corneal Epithelial Thickness in Dry Eye Patients

      Purpose To investigate the features of corneal epithelial thickness topography with Fourier-domain optical coherence tomography (OCT) in dry eye patients. Methods In this cross-sectional study, 100 symptomatic dry eye patients and 35 normal subjects were enrolled. All participants answered the ocular surface disease index questionnaire and were subjected to OCT, corneal fluorescein staining, tear breakup time, Schirmer 1 test without anesthetic (S1t), and meibomian morphology. Several epithelium statistics for each eye, including central, superior, inferior, minimum, maximum, minimum − maximum, and map standard deviation, were averaged. Correlations of epithelial thickness with the symptoms of dry eye were calculated. Results The mean ...

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    18. Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG Capsulotomy: a case series

      Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG Capsulotomy: a case series

      Background Posterior capsule opacification (PCO) is the most common post-operative complication associated with cataract surgery and is mostly treated with Nd:YAG laser capsulotomy. Here, we demonstrate the use of high-resolution spectral-domain optical coherence tomography (OCT) as a technique for PCO analysis. Additionally, we evaluate the influence of PCO types and the distance between the intraocular lens (IOL) and the posterior capsule (PC), i.e., the IOL/PC distance, on the total-pulse energy required for the Nd:YAG laser posterior capsulotomy. Methods 47 eyes with PCO scheduled for the Nd:YAG procedure were examined and divided into four categories: fibrosis ...

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    19. Anterior chamber depth measurements using Scheimpflug imaging and optical coherence tomography: Repeatability, reproducibility, and agreement

      Anterior chamber depth measurements using Scheimpflug imaging and optical coherence tomography: Repeatability, reproducibility, and agreement

      Purpose To determine the repeatability, reproducibility, and agreement of anterior chamber depth (ACD) measurements obtained with 3 Scheimpflug cameras and an anterior segment optical coherence tomography (AS-OCT) device. Setting Eye Hospital of Wenzhou Medical University, Zhejiang, China. Design Observational cross-sectional study. Methods Two observers took 3 consecutive measurements in healthy right eyes using each device to assess intraoperator repeatability. The mean values obtained at different sessions by the first operator were used to determine the intersession reproducibility. Three consecutive measurements obtained by the first operator at the first session were averaged and used to assess agreement. Results The ACD measurements ...

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    20. Poppers Maculopathy: Complete Restitution of Macular Changes in OCT after Drug Abstinence

      Poppers Maculopathy: Complete Restitution of Macular Changes in OCT after Drug Abstinence

      Background : “ Poppers ” is a slang term for a group of alkyl nitrites that are used as recreational drugs . Their inhalative intoxication leads to muscle relaxation, analgesia, and euphoria. Maculopathy is a rare but serious side-effect. Patients/Methods : Clinical, imaging, and electrophysiological findings of seven patients with maculopathy after consumption of poppers were presented. Results : All seven patients were male with a median age of 35 years (range 28–45 years), the median duration of periodical poppers use until the onset of symptoms was 9.8 years (one day to 25 years). Five of seven patients were HIV-positive, one patient was ...

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    21. A New OCT-based Method to Generate Virtual Maps of Vitreomacular Interface Pathologies

      A New OCT-based Method to Generate Virtual Maps  of Vitreomacular Interface Pathologies

      Optical coherence tomography (OCT) is the most accurate modality for noninvasive assessment of vitreoretinal interface (VRI). The scientific objective of research presented in this paper was to develop a new OCT-based method for investigation of vitreomacular interface pathologies in human eyes. We propose a new approach for the automatic generation of virtual maps representing the distance between the posterior surface of the hyaloid (PSH) and the inner limiting membrane (ILM) in the vitreomacular traction (VMT) pathology. Volumetric data was acquired from 3 adult patients with VMT. OCT B-scans were processed frame-by-frame and refined by advanced digital imaging algorithms, including application ...

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    22. Glaucoma Module Premium Edition for SPECTRALIS to be Showcased at Annual Optometric Press Conference

      Glaucoma Module Premium Edition for SPECTRALIS to be Showcased at Annual Optometric Press Conference

      Heidelberg Engineering GmbH, the global ophthalmic imaging company, is presenting the Glaucoma Module Premium Edition for SPECTRALIS at the annual 2014 American Academy of Optometry Professional Press Conference in Denver, CO. The Glaucoma Module Premium Edition for SPECTRALIS* module combines a proprietary technology called Anatomic Positioning System (APS) with a series of unique scan patterns. The APS creates an anatomic map of each eye. The center of the optic nerve head and the fovea are detected via a short pre-scan function. The map is aligned according to these anatomical landmarks, individually for each eye. Subsequent scans are oriented to this ...

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