1. Articles in category: Ophthalmology

    577-600 of 5888 « 1 2 ... 22 23 24 25 26 27 28 ... 244 245 246 »
    1. Progress on Developing Adaptive Optics–Optical Coherence Tomography for In Vivo Retinal Imaging: Monitoring and Correction of Eye Motion Artifacts

      Progress on Developing Adaptive Optics–Optical Coherence Tomography for In Vivo Retinal Imaging: Monitoring and Correction of Eye Motion Artifacts

      Recent progress in retinal image acquisition techniques, including optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO), combined with improved performance of adaptive optics (AO) instrumentation, has resulted in improvement in the quality of in vivo images of cellular structures in the human retina. Here, we present a short review of progress on developing AO-OCT instruments. Despite significant progress in imaging speed and resolution, eye movements present during acquisition of a retinal image with OCT introduce motion artifacts into the image, complicating analysis and registration. This effect is especially pronounced in high-resolution datasets acquired with AO-OCT instruments. Several retinal tracking ...

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    2. A novel view of punctate inner choroidopathy: Characterizing the serial changes by high resolution spectrum-domain optical coherence tomography

      A novel view of punctate inner choroidopathy: Characterizing the serial changes by high resolution spectrum-domain optical coherence tomography

      Purpose We report a case of punctate inner choroidopathy (PIC) treated with oral prednisolone and intravitreous bevacizumab injection (IVB). Methods One case was studied and followed for 5 months by serial spectrum-domain optical coherence tomography (SD-OCT). Results At the early active phase of PIC, SD-OCT showed dome-shaped retinal pigment epithelium (RPE) elevation with underlying intact Bruch's membrane (BM), overlying photoreceptor inner/outer segment junction (PRJ) disappearance, and homogenous hyperreflective sub-RPE signals. After oral prednisolone and IVB, SD-OCT showed resolution of RPE changes with overlying intact PRJ. Further, the localized outer retinal layers were found to gradually move outward. Conclusions ...

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    3. Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror

      Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror

      We developed an ultrahigh speed, handheld swept source optical coherence tomography (SS-OCT) ophthalmic instrument using a 2D MEMS mirror. A vertical cavity surface-emitting laser (VCSEL) operating at 1060 nm center wavelength yielded a 350 kHz axial scan rate and 10 µm axial resolution in tissue. The long coherence length of the VCSEL enabled a 3.08 mm imaging range with minimal sensitivity roll-off in tissue. Two different designs with identical optical components were tested to evaluate handheld OCT ergonomics. An iris camera aided in alignment of the OCT beam through the pupil and a manual fixation light selected the imaging ...

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    4. Early Detection of Blinding Eye Disease Could be as Easy as Scanning a Barcode

      Early Detection of Blinding Eye Disease Could be as Easy as Scanning a Barcode

      New hand-held optical device to catch early signs of retinal disease WASHINGTON, Dec. 20, 2013—A new optical device puts the power to detect eye disease in the palm of a hand. The tool—about the size of a hand-held video camera—scans a patient’s entire retina in seconds and could aid primary care physicians in the early detection of a host of retinal diseases including diabetic retinopathy, glaucoma and macular degeneration. Researchers at the Massachusetts Institute of Technology (MIT) describe their new ophthalmic-screening instrument in a paper published today in the open-access journal Biomedical Optics Express , published by ...

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    5. Is Handheld Optical Coherence Tomography Reliable in Infants and Young Children With and Without Nystagmus?

      Is Handheld Optical Coherence Tomography Reliable in Infants and Young Children With and Without Nystagmus?

      Purpose. To evaluate the reliability of the spectral domain handheld OCT (HH-OCT) in assessing foveal morphology in children with and without nystagmus. Methods. Forty-nine subjects with nystagmus (mean age 43.83 months; range, 1–82 months) and 48 controls (mean age 43.02 months; range, 0 to 83 months) were recruited and scanned using HH-OCT. A minimum of two separate volumetric scans on the same examination day of the fovea were obtained. The images were imported into ImageJ software where manual retinal layer segmentation of the central foveal B-scan was performed. Agreement between scans was assessed by determining the intraclass ...

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    6. In Vivo Lamina Cribrosa Micro-Architecture in Healthy and Glaucomatous Eyes as Assessed by Optical Coherence Tomography

      In Vivo Lamina Cribrosa Micro-Architecture in Healthy and Glaucomatous Eyes as Assessed by Optical Coherence Tomography

      Purpose. The lamina cribrosa (LC) is a prime location of glaucomatous damage. The purpose of this study was to compare LC 3-dimensional micro-architecture between healthy and glaucomatous eyes in vivo by using optical coherence tomography (OCT). Methods. Sixty-eight eyes (19 healthy and 49 glaucomatous) from 47 subjects were scanned in a 3.5 × 3.5 × 3.64-mm volume (400 × 400 × 896 pixels) at the optic nerve head by using swept-source OCT. The LC micro-architecture parameters were measured on the visible LC by an automated segmentation algorithm. The LC parameters were compared to diagnosis and visual field mean deviation (VF MD ...

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    7. Ophthalmology, 4th Edition (Textbook)

      Ophthalmology, 4th Edition (Textbook)

      Get the quick answers you need on every aspect of clinical ophthalmology and apply them in your day-to-day practice . The latest edition of Ophthalmology by Drs. Yanoff and Duker presents practical, expert, concise guidance on nearly every ophthalmic condition and procedure, equipping you to efficiently overcome whatever clinical challenges you may face.

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    8. Choriocapillaris and Choroidal Microvasculature Imaging with Ultrahigh Speed OCT Angiography

      Choriocapillaris and Choroidal Microvasculature Imaging with Ultrahigh Speed OCT Angiography

      We demonstrate in vivo choriocapillaris and choroidal microvasculature imaging in normal human subjects using optical coherence tomography (OCT). An ultrahigh speed swept source OCT prototype at 1060 nm wavelengths with a 400 kHz A-scan rate is developed for three-dimensional ultrahigh speed imaging of the posterior eye. OCT angiography is used to image three-dimensional vascular structure without the need for exogenous fluorophores by detecting erythrocyte motion contrast between OCT intensity cross-sectional images acquired rapidly and repeatedly from the same location on the retina. En face OCT angiograms of the choriocapillaris and choroidal vasculature are visualized by acquiring cross-sectional OCT angiograms volumetrically ...

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    9. Effect of scan quality on diagnostic accuracy of spectral domain optical coherence tomography in glaucoma

      Effect of scan quality on diagnostic accuracy of spectral domain optical coherence tomography in glaucoma

      Purpose To evaluate the effect of scan quality on the diagnostic accuracies of optic nerve head (ONH), retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) parameters of spectral domain optical coherence tomography (SD-OCT) in glaucoma. Design Cross-sectional study. Methods 252 eyes of 183 control subjects (mean MD: -1.84 dB) and 207 eyes of 159 glaucoma patients (mean MD: -7.31 dB) underwent ONH, RNFL and GCC scanning with SD-OCT. Scan quality of SD-OCT images was based on signal strength index (SSI) values. Influence of SSI on diagnostic accuracy of SD-OCT was evaluated by receiver operating characteristic (ROC ...

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    10. A Comparison of Methods for Tracking Progression in X-Linked Retinitis Pigmentosa Using Frequency Domain OCT

      A Comparison of Methods for Tracking Progression in X-Linked Retinitis Pigmentosa Using Frequency Domain OCT

      PURPOSE: To compare the efficacy of frequency domain optical coherence tomography (fdOCT)-derived outer retinal measures in tracking disease progression in x-linked (xl) retinitis pigmentosa (RP) patients. METHODS: Macular volume scans and line scans (Spectralis) were obtained from 27 xlRP patients (15.3 ± 6.4 years) at two visits approximately 2 years apart. Changes in average outer retinal layer thicknesses across the volume scan were compared to changes detected by measures derived from the edge of the inner segment ellipsoid zone (EZ) band, that is, where the EZ band (also known as inner segment/outer segment border) disappears. Repeatability was ...

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    11. Measurement of retinal nerve fiber layer thickness in eyes with optic disc swelling by using scanning laser polarimetry and optical coherence tomography

      Measurement of retinal nerve fiber layer thickness in eyes with optic disc swelling by using scanning laser polarimetry and optical coherence tomography

      Background: The retinal nerve fiber layer thickness (RNFLT) in patients with optic disc swelling of different etiologies was compared using scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (OCT). Methods: Forty-seven patients with optic disc swelling participated in the cross-sectional study. Both GDx SLP (enhanced corneal compensation) and Spectralis spectral-domain OCT measurements of RNFLT were made in 19 eyes with papilledema (PE), ten eyes with optic neuritis (ON), and 18 eyes with nonarteritic anterior ischemic optic neuropathy (NAION) at the neuro-ophthalmology clinic at Kyoto University Hospital. Differences in SLP (SLP-RNFLT) and OCT (OCT-RNFLT) measurements among different etiologies were investigated ...

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    12. Spontaneous resolution of foveal detachment in dome-shaped macula observed by spectral domain optical coherence tomography

      Spontaneous resolution of foveal detachment in dome-shaped macula observed by spectral domain optical coherence tomography

      Dome-shaped macula (DSM) was described by Gaucher et al as a convex protrusion of macula within a staphyloma in highly myopic eyes that causes visual impairment associated with serous foveal detachment (SFD). We describe a patient with spontaneous resolution of SFD in DSM documented by serial spectral domain optical coherence tomography (SD-OCT). A 28-year-old female Japanese patient presented with blurred vision in both eyes. Upon examination, her best-corrected visual acuity was 1.2 with -8.0 sphere and 0.5 with -8.0 sphere in the right and left eyes, respectively. SD-OCT in both eyes showed an anterior bulge of ...

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    13. OCT for glaucoma diagnosis, screening and detection of glaucoma progression

      OCT for glaucoma diagnosis, screening and detection of glaucoma progression

      Optical coherence tomography (OCT) is a commonly used imaging modality in the evaluation of glaucomatous damage. The commercially available spectral domain (SD)-OCT offers benefits in glaucoma assessment over the earlier generation of time domain-OCT due to increased axial resolution, faster scanning speeds and has been reported to have improved reproducibility but similar diagnostic accuracy. The capabilities of SD-OCT are rapidly advancing with 3D imaging, reproducible registration, and advanced segmentation algorithms of macular and optic nerve head regions. A review of the evidence to date suggests that retinal nerve fibre layer remains the dominant parameter for glaucoma diagnosis and detection ...

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    14. Characterization of the Choroid-Scleral Junction and Suprachoroidal Layer in Healthy Individuals on Enhanced-Depth Imaging Optical Coherence Tomography

      Characterization of the Choroid-Scleral Junction and Suprachoroidal Layer in Healthy Individuals on Enhanced-Depth Imaging Optical Coherence Tomography

      Importance Accurate measurements of choroidal thickness (CT) using enhanced-depth imaging optical coherence tomography (EDI-OCT) require a well-defined choroid-scleral junction (CSJ), which may appear in some eyes as a hyporeflective band corresponding to the suprachoroidal layer (SCL). Objective To identify factors associated with the presence and thickness of the SCL in healthy participants and determine how different CSJ boundary definitions impact CT measurements. Design, Setting, and Participants Secondary analysis of EDI-OCT images obtained prospectively from 74 eyes of 74 controls (mean age, 68.6 years) from the Age-Related Eye Disease Study 2 Ancillary SDOCT Study. Main Outcomes and Measures The CSJ ...

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    15. A comparison of false positives in retinal nerve fiber layer, optic nerve head and macular ganglion cell-inner plexiform layer from two spectral-domain optical coherence tomography devices

      A comparison of false positives in retinal nerve fiber layer, optic nerve head and macular ganglion cell-inner plexiform layer from two spectral-domain optical coherence tomography devices

      BACKGROUND: The incidence of false positive (FP) results of optic coherence tomography (OCT) retinal nerve fiber layer (RNFL) color code in healthy subjects can be very high with Cirrus OCT. Recent evidence has shown that OCT parameters derived from macular ganglion cell-inner plexiform layer (GCIPL) have excellent ability to discriminate between normal eyes and eyes with early glaucoma. METHODS: This was a prospective, cross-sectional study. One hundred eyes from 50 healthy volunteers underwent circumpapillary scanning by Cirrus and Spectralis OCT and macular scanning using Cirrus OCT. FP rates for each of the OCT parameters, using predefined criteria for an abnormal ...

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    16. Axial Biometry of the Entire Eye Using Ultra-Long Scan Depth Optical Coherence Tomography

      Axial Biometry of the Entire Eye Using Ultra-Long Scan Depth Optical Coherence Tomography

      Purpose To assess the repeatability of axial biometry of the entire eye using ultra-long scan depth optical coherence tomography (OCT) and to investigate the agreement with IOLMaster measurements (Carl Zeiss Meditec). Design Prospective, observational case series. Methods There were 37 adult subjects enrolled in group 1 and 12 adult subjects enrolled in group 2. Using ultra-long scan depth OCT, the left eyes of these groups were measured in 2 separate sessions. The images were processed by a manual method and custom-developed automatic software. A model eye was imaged for verification. The subjects in group 2 were imaged using ultra-long scan ...

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    17. Fully Automated Biometry of In Situ Intraocular Lenses Using Long Scan Depth Spectral-Domain Optical Coherence Tomography

      Fully Automated Biometry of In Situ Intraocular Lenses Using Long Scan Depth Spectral-Domain Optical Coherence Tomography

      Purpose: Spectral-domain optical coherence tomography (SD-OCT) was used to automatically measure accommodative biometric changes in the anterior segment of eyes implanted with an intraocular lens (IOL). The repeatability and reliability of the automated measurements were also evaluated. Methods: Long scan depth SD-OCT was used to image the anterior segment of eyes implanted with IOLs. A fully automated algorithm was used to detect the boundaries of the cornea and IOL and yielded the measurements. The results included anterior segment dimensions in IOL eyes and the deflection of the IOLs. Automated measurements were validated in vitro and compared with the manual results ...

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    18. Acute angle closure: qualitative and quantitative evaluation of the anterior segment using anterior segment Optical Coherence Tomography

      Acute angle closure: qualitative and quantitative evaluation of the anterior segment using anterior segment Optical Coherence Tomography

      Background To evaluate different mechanisms of acute angle closure(AAC), and to compare it with unaffected fellow eyes and primary angle closure suspects(PACS) using anterior segment optical coherence tomography(AS-OCT). Design Prospective, cross-sectional Methods In this clinic-based study,116 eyes(76 patients) with angle closure disease were included and categorized into three groups:1) AAC(40 eyes); 2) fellow eyes of AAC(40 eyes); and 3) PACS(36 eyes). Complete ophthalmic examinations including gonioscopy, A-scan biometry, and AS-OCT were performed. Main outcome measure Based on the AS-OCT images, 4 mechanisms of PAC including pupil block, plateau iris configuration, thick ...

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    19. Width of anterior chamber angle determined by OCT, and correlation to refraction and age in a German working population: the MIPH Eye&Health Study

      Width of anterior chamber angle determined by OCT, and correlation to refraction and age in a German working population: the MIPH Eye&Health Study

      Background Optical coherence tomography (OCT) of the anterior segment allows quantitative analysis of the geometry of the chamber angle. We performed bilateral spectral-domain OCT measurements in healthy, emmetropic, hyperopic, and myopic subjects to establish correlations between the width of the angle, the refraction, and intraocular pressure of the test persons. Methods Out of 4,617 eyes (2,309 subjects), those with refractive errors of < −4 or > +3 diopters were identified by objective refraction measurement (KR-8800 Kerato-Refractometer, Topcon Inc., Japan) and examined using the anterior segment mode of a spectral-domain 3D OCT-2000 (Topcon Inc., Japan). Non-contact tonometry was performed (CT-80, Topcon ...

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    20. Two-dimensional segmentation of the retinal vascular network from optical coherence tomography

      Two-dimensional segmentation of the retinal vascular network from optical coherence tomography

      The automatic segmentation of the retinal vascular network from ocular fundus images has been performed by several research groups. Although different approaches have been proposed for traditional imaging modalities, only a few have addressed this problem for optical coherence tomography (OCT). Furthermore, these approaches were focused on the optic nerve head region. Compared to color fundus photography and fluorescein angiography, two-dimensional ocular fundus reference images computed from three-dimensional OCT data present additional problems related to system lateral resolution, image contrast, and noise. Specifically, the combination of system lateral resolution and vessel diameter in the macular region renders the process particularly ...

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    21. Shear wave imaging optical coherence tomography (SWI-OCT) for ocular tissue biomechanics

      Shear wave imaging optical coherence tomography (SWI-OCT) for ocular tissue biomechanics

      We report on a noncontact low-coherence optical phase-based imaging method, termed shear wave imaging optical coherence tomography (SWI-OCT), which enables 2D depth-resolved visualization of the low-amplitude elastic wave propagation in tissue with ultrahigh frame rate. SWI-OCT is based on 1D transverse scanning of the M-mode OCT imaging that is precisely synchronized with a low-pressure short-duration air-puff loading system. This approach of scanning and data recording allows visualization of the induced tissue deformation at high frame rate. The applied phase-resolved interferometric technique, with sensitivity on the nanometer scale, makes the low-amplitude tissue displacement detectable. For the demonstration of this method, and ...

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    22. Hyperreflective Intraretinal Spots in Diabetics without and with Nonproliferative Diabetic Retinopathy: An In Vivo Study Using Spectral Domain OCT

      Hyperreflective Intraretinal Spots in Diabetics without and with Nonproliferative Diabetic Retinopathy: An In Vivo Study Using Spectral Domain OCT

      Purpose . To evaluate the presence of hyperreflective spots (HRS) in diabetic patients without clinically detectable retinopathy (no DR) or with nonproliferative mild to moderate retinopathy (DR) without macular edema, and compare the results to controls. Methods . 36 subjects were enrolled: 12 with no DR, 12 with DR, and 12 normal subjects who served as controls. All studied subjects underwent full ophthalmologic examination and spectral domain optical coherence tomography (SD-OCT). SD-OCT images were analyzed to measure and localize HRS. Each image was analyzed by two independent, masked examiners. Results . The number of HRS was significantly higher in both diabetics without and ...

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    23. Bioptigen Introduces Dynamic 3D Tissue Flattening Software for Envisu SD-OCT Systems (See Video)

      Bioptigen Introduces Dynamic 3D Tissue Flattening Software for Envisu SD-OCT Systems  (See Video)

      Bioptigen Inc. announced today the introduction of Envisu Apps, modular image processing software for improved analysis and visualization of high resolution volumetric OCT images. The first app, named Dynamic 3D Tissue Flattening uses fully automated retinal layer segmentations for enhanced en face views. These retinal layer segmentations allow users to eliminate motion artifacts (such as respiration, cardiac, etc.) which often occur during in vivo image acquisition, thus en face views appear perfectly flat across the entire image. “Single pixel slices are possible across the whole 3D image, allowing uniform sampling of data along a warped contour that ‘cuts’ through the ...

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