1. Articles from Fan Lu

    1-24 of 40 1 2 »
    1. Long scan depth optical coherence tomography on imaging accommodation: impact of enhanced axial resolution, signal-to-noise ratio and speed

      Long scan depth optical coherence tomography on imaging accommodation: impact of enhanced axial resolution, signal-to-noise ratio and speed

      Background Spectral domain optical coherence tomography (SD-OCT) was a useful tool to study accommodation in human eye, but the maximum image depth is limited due to the decreased signal-to-noise ratio (SNR). In this study, improving optical resolutions, speeds and the SNR were achieved by custom built SD-OCT, and the evaluation of the impact of the improvement during accommodation was investigated. Methods Three systems with different spectrometer designs, including two Charge Coupled Device (CCD) cameras and one Complementary Metal-Oxide-Semiconductor Transistor (CMOS) camera, were tested. We measured the point spread functions of a mirror at different positions to obtain the axial resolution ...

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    2. Inner Retinal Microvasculature Damage Correlates With Outer Retinal Disruption During Remission in Behçet's Posterior Uveitis by Optical Coherence Tomography Angiography

      Inner Retinal Microvasculature Damage Correlates With Outer Retinal Disruption During Remission in Behçet's Posterior Uveitis by Optical Coherence Tomography Angiography

      Purpose : To quantify the inner retinal vascular changes that occur in the superficial and deep layers in patients with Behçet's disease (BD) in remission using optical coherence tomography angiography (OCTA) and to evaluate the associations with outer retinal structure. Methods : Nineteen eyes from 19 patients with BD in remission were enrolled, including 10 eyes with less than five ocular attacks ( n < 5) and nine eyes with five or more attacks ( n ≥ 5). The foveal avascular zone (FAZ) and global and regional vessel density (VD) in both layers were compared between BD eyes and normal eyes. Their outer retinal ...

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    3. Axial elongation measured by long scan depth optical coherence tomography during pilocarpine-induced accommodation in intraocular lens-implanted eyes

      Axial elongation measured by long scan depth optical coherence tomography during pilocarpine-induced accommodation in intraocular lens-implanted eyes

      We used an ultra-long scan depth optical coherence tomography (UL-OCT) system to investigate changes in axial biometry of pseudophakic eyes during pilocarpine- induced accommodation. The right eyes from 25 healthy subjects (age range 49 to 84 years) with an intraocular lens (IOL) were imaged twice in the non-accommodative and the accommodative states. A custom-built UL-OCT instrument imaged the whole eye. Then accommodation was induced by two drops of 0.5% pilocarpine hydrochloride separated by a 5-minute interval. Following the same protocol, images were acquired again 30 minutes after the first drop. The central corneal thickness (CCT), anterior chamber depth (ACD ...

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    4. Characterization of Soft Contact Lens Fitting Using Ultra-Long Scan Depth Optical Coherence Tomography

      Characterization of Soft Contact Lens Fitting Using Ultra-Long Scan Depth Optical Coherence Tomography

      Objectives . To evaluate the centration and movement of soft contact lenses and to verify the repeatability of two repeated measurements of the lens centration and movement using ultra-long scan depth optical coherence tomography (UL-OCT). Methods . A 1-day Acuvue® Define™ lens was tested on both eyes of 10 subjects (5 males and 5 females; mean age, 31.6 years). The centration and blink-induced movement of the contact lens were measured using UL-OCT at 5 min and 30 min after insertion. The measurements were repeated once at each checkpoint. Results . Good repeatability was found in the lens centration and movement between the ...

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    5. Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue

      Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue

      We report on a real-time acoustic radiation force optical coherence elastography (ARF-OCE) system to map the relative elasticity of corneal tissue. A modulated ARF is used as excitation to vibrate the cornea, while OCE serves as detection of tissue response. To show feasibility of detecting mechanical contrast using this method, we performed tissue-equivalent agarose phantom studies with inclusions of a different stiffness. We obtained 3-D elastograms of a healthy cornea and a highly cross-linked cornea. Finally, we induced a stiffness change on a small portion of a cornea and observed the differences in displacement.

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    6. Automatic three-dimensional segmentation combined with in vivo microvascular network imaging of human retina by intensity-based Doppler variance optical coherence tomography

      Automatic three-dimensional segmentation combined with in vivo microvascular network imaging of human retina by intensity-based Doppler variance optical coherence tomography

      Optical coherence tomography (OCT) is a noninvasive method for retinal imaging. In this work, we present an in vivo human retinal microvascular network measurement by an intensity-based Doppler variance (IBDV) based on sweptsource OCT. In addition, an automatic three-dimensional (3-D) segmentation method was used for segmenting intraretinal layers. The microvascular networks were divided into six layers by visualizing of each individual layer with enhanced imaging contrast. This method has potential for earlier diagnosis and precise monitoring in retinal vascular diseases.

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    7. In vivo microvascular network imaging of the human retina combined with an automatic three-dimensional segmentation method

      In vivo microvascular network imaging of the human retina combined with an automatic three-dimensional segmentation method

      Microvascular network of the retina plays an important role in diagnosis and monitoring of various retinal diseases. We propose a three-dimensional (3-D) segmentation method with intensity-based Doppler variance (IBDV) based on swept-source optical coherence tomography. The automatic 3-D segmentation method is used to obtain seven surfaces of intraretinal layers. The microvascular network of the retina, which is acquired by the IBDV method, can be divided into six layers. The microvascular network of the six individual layers is visualized, and the morphology and contrast images can be improved by using the segmentation method. This method has potential for earlier diagnosis and ...

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    8. Macular Thickness Profiles of Intra-retinal Layers in Myopia Evaluated by Ultra-High Resolution Optical Coherence Tomography

      Macular Thickness Profiles of Intra-retinal Layers in Myopia Evaluated by Ultra-High Resolution Optical Coherence Tomography

      Purpose To investigate the thickness and variation profiles of eight intra-retinal layers in myopia. Design Prospective cross-sectional study. Methods Young subjects with spherical equivalents ranging from +0.50 to -10.25 diopters and good corrected vision were divided into emmetropic (n=20), low myopic (n=50), and high myopic (n=30) groups. Retinal images centered on the fovea along the horizontal and vertical meridians were obtained by ultra-high resolution optical coherence tomography (OCT). Macular images were segmented into eight intra-retinal layers by an automatic segmentation algorithm to yield thickness profiles within a 6-mm diameter circle divided into central, pericentral, and ...

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    9. Biometry of Anterior Segment of Human Eye on Both Horizontal and Vertical Meridians during Accommodation Imaged with Extended Scan Depth Optical Coherence Tomography

      Biometry of Anterior Segment of Human Eye on Both Horizontal and Vertical Meridians during Accommodation Imaged with Extended Scan Depth Optical Coherence Tomography

      Purpose To determine the biometry of anterior segment dimensions of the human eye on both horizontal and vertical meridians with extended scan depth optical coherence tomography (OCT) during accommodation. Methods Twenty pre-presbyopic volunteers, aged between 24 and 30, were recruited. The ocular anterior segment of each subject was imaged using an extended scan depth OCT under non- and 3.0 diopters (D) of accommodative demands on both horizontal and vertical meridians. All the images were analyzed to yield the following parameters: pupil diameter (PD), anterior chamber depth (ACD), anterior and posterior surface curvatures of the crystalline lens (ASC and PSC ...

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    10. Automatic Biometry of the Anterior Segment During Accommodation Imaged by Optical Coherence Tomography

      Automatic Biometry of the Anterior Segment During Accommodation Imaged by Optical Coherence Tomography

      Objective: To test accuracy and repeatability of a software algorithm that performs automatic biometry of the anterior segment of the human eye imaged with long scan depth optical coherence tomography (OCT). Methods: The ocular anterior segment imaging was performed with custom-built long scan depth OCT. An automatic software algorithm including boundary segmentation, image registration, and optical correction was developed for fast and reliable biometric measurements based on the OCT images. The boundary segmentation algorithm mainly used the gradient information of images and applied the shortest path search based on the dynamic programming to optimize the edge finding. The automatic algorithm ...

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    11. Repeatability and Reproducibility of Eight Macular Intra-Retinal Layer Thicknesses Determined by an Automated Segmentation Algorithm Using Two SD-OCT Instrument

      Repeatability and Reproducibility of Eight Macular Intra-Retinal Layer Thicknesses Determined by an Automated Segmentation Algorithm Using Two SD-OCT Instrument

      Purpose To evaluate the repeatability, reproducibility, and agreement of thickness profile measurements of eight intra-retinal layers determined by an automated algorithm applied to optical coherence tomography (OCT) images from two different instruments. Methods Twenty normal subjects (12 males, 8 females; 24 to 32 years old) were enrolled. Imaging was performed with a custom built ultra-high resolution OCT instrument (UHR-OCT, ~3 µm resolution) and a commercial RTVue100 OCT (~5 µm resolution) instrument. An automated algorithm was developed to segment the macular retina into eight layers and quantitate the thickness of each layer. The right eye of each subject was imaged two ...

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    12. Agreement of Corneal Epithelial Profiles Produced by Automated Segmentation of SD-OCT Images Having Different Optical Resolutions

      Agreement of Corneal Epithelial Profiles Produced by Automated Segmentation of SD-OCT Images Having Different Optical Resolutions

      Objective: Using a custom-developed segmentation algorithm, agreement of corneal epithelial thickness profile measurements between two spectral domain optical coherence tomography (SD-OCT) systems was assessed. Methods: Eighteen left eyes (18 subjects; mean+/-standard deviation; age, 23.2+/-0.9 years) were imaged twice on nonconsecutive days by a custom-built ultra-high resolution OCT (UHR-OCT) system and a commercial RTVue OCT system. A segmentation algorithm based on axial gradient information and a shortest path search was developed to measure corneal epithelial thickness profiles from the SD-OCT images. Results: There was good correlation between the automated and manual segmentation positions of the epithelium. The ...

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    13. 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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    14. Phacoemulsification Induced Transient Swelling of Corneal Descemet’s Endothelium Complex Imaged with Ultra-High Resolution Optical Coherence Tomography

      Phacoemulsification Induced Transient Swelling of Corneal Descemet’s Endothelium Complex Imaged with Ultra-High Resolution Optical Coherence Tomography

      Purpose Thickness changes of corneal sub-layers after phacoemulsification were investigated by spectral domain ultra-high resolution optical coherence tomography (UHR-OCT). Methods The corneas (n = 26) of 26 age-related cataract surgery patients were studied. UHR-OCT was used to evaluate the thickness of Descemet’s Endothelium Complex (DEC), stroma, Bowman’s layer, epithelium, and full cornea at the center (CCT) before, one day after, and one week after surgery. Non-contact specular microscopy measured CCT, endothelial cell density, and morphology. Results The DEC, stroma, Bowman’s layer, and epithelium were visualized by UHR-OCT. Before surgery, the DEC in all cases appeared as a translucent ...

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    15. Ocular anterior segment biometry and high-order wavefront aberrations during accommodation

      Ocular anterior segment biometry and high-order wavefront aberrations during accommodation

      Purpose: To investigate the relationships between the ocular anterior segment biometry and the ocular high-order aberrations (HOAs) during accommodation by combined ultra-long scan depth optical coherence tomography (UL-OCT) and wavefront sensor. Methods: Thirty-five right eyes of young healthy subjects (21 women and 14 men; age: 25.6 ± 3.1 years; spherical equivalent refractive error: -0.41 ± 0.59 D) were enrolled. A custom-built UL-OCT and a wavefront sensor were combined. They were able to image the ocular anterior segment and to measure the HOAs during accommodation. The differences in the biometric dimensions and in the HOAs between the non-accommodative and ...

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    16. High resolution OCT quantitative analysis of the space between the IOL and the posterior capsule during the early cataract post-operative period

      High resolution OCT quantitative analysis of the space between the IOL and the posterior capsule during the early cataract post-operative period

      Purpose: To quantitatively characterize the space between the intraocular lens (IOL) and the posterior capsule (IOL-PC space) during the early post-phacoemulsification period, using high resolution optical coherence tomography (OCT). Methods: Thirty eyes of 30 patients who underwent phacoemulsification were recruited and randomly divided into two groups. Acrysof Natural IQ IOLs were implanted in one group (n = 15), and Adapt-AO IOLs were implanted into the other (n = 15). A custom built OCT instrument was used to image the IOL-PC space at 1 day, 1 week, and 1 month after surgery. Slit-lamp examination and auto refraction were performed at each visit. Results ...

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    17. Entire Thickness Profiles of the Epithelium and Contact Lens In Vivo Imaged With High-Speed and High-Resolution Optical Coherence Tomography

      Entire Thickness Profiles of the Epithelium and Contact Lens In Vivo Imaged With High-Speed and High-Resolution Optical Coherence Tomography

      Purpose: To test the feasibility of measuring the entire thickness profiles of the epithelium and contact lens (CL) in vivo, using high-speed and high-resolution spectral-domain optical coherence tomography (SD-OCT). Methods: A custom-built, long scan depth SD-OCT was developed based on a complementary metal oxide semiconductor (CMOS) camera, and the axial resolution was approximately 5.1 μm in tissue. Five eyes of five subjects were imaged twice across the horizontal meridian before and while wearing one CL. Semiautomatic measurement was done to yield the entire thickness profiles of the epithelium, total cornea, and CL after correcting for optical distortion. Results: The ...

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    18. Simultaneous real-time imaging of the ocular anterior segment including the ciliary muscle during accommodatio

      Simultaneous real-time imaging of the ocular anterior segment including the ciliary muscle during accommodatio

      We demonstrated a novel approach of imaging the anterior segment including the ciliary muscle using combined and synchronized two spectral domain optical coherence tomography devices (SD-OCT). In one SD-OCT, a Complementary Metal-Oxide-Semiconductor Transistor (CMOS) camera and an alternating reference arm was used to image the anterior segment from the cornea to the lens. Another SD-OCT for imaging the ciliary muscle was equipped with a light source with a center wavelength of 1,310 nm and a bandwidth of 75 nm. Repeated measurements were performed under relaxed and 4.00 D accommodative stimulus states in six eyes from 6 subjects. We ...

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    19. Retinal nerve fibre layer thickness and macular thickness in patients with esotropic amblyopia

      Retinal nerve fibre layer thickness and macular thickness in patients with esotropic amblyopia

      Background The objective of this study was to evaluate the retinal nerve fibre layer thickness (RNFLT) and retinal macular thickness (RMT) in esotropic amblyopic children. Methods Twenty-one children diagnosed with esotropic amblyopia at Strabismus and Amblyopia Department of Wenzhou Medical College Affiliated Eye Hospital, China, were enrolled in the study. Their fellow eyes were normal and were used as controls. RNFLT and RMT were measured by optical coherence tomography (OCT). Results The fovea and the central sector of the retina in amblyopic eyes were slightly but not significantly thicker than those in the normal fellow eyes. There was no significant ...

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    20. Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery

      Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery

      AIM : To investigate the effect of simulated dynamic intraocular pressure (SDIOP) during uncomplicated phacoemulsification on postoperative macular and peripapillary retinal nerve fiber layer (RNFL) thickness. METHODS : Macular and RNFL thicknesses in one eye of patients (n=30) undergoing uncomplicated phacoemulsification were measured by optical coherence tomography preoperatively and 1 week postoperatively. The best-corrected visual acuity, SDIOP, irrigation time (IT), effective phacoemulsification time, entire surgical duration, blood pressure, and heart rate were recorded. RESULTS : The mean SDIOP and IT was (74.9 ± 27.4)cmH2O and (178.4 ± 21.6) seconds respectively. We divided our patients into two groups based upon ...

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    21. Capsular Adhesion to Intraocular Lens in Highly Myopic Eyes Evaluated In Vivo Using Ultralong-scan-depth Optical Coherence Tomography

      Capsular Adhesion to Intraocular Lens in Highly Myopic Eyes Evaluated In Vivo Using Ultralong-scan-depth Optical Coherence Tomography

      Purpose To evaluate the in vivo capsular apposition to the intraocular lens (IOL) in subjects with high myopia by ultralong-scan-depth optical coherence tomography (OCT). Design Prospective observational case series. Methods Forty eyes from 40 cataract patients scheduled for phacoemulsification surgery at the Affiliated Eye Hospital, Wenzhou Medical College were studied, of which 20 eyes were highly myopic (axial length >26 mm) and 20 eyes were emmetropic (22 mm < axial length <24.5 mm). All eyes were examined with a custom-built ultralong-scan-depth OCT at 4 hours, 1 day, 7 days, 14 days, and 28 days after surgery. Results Anterior capsule contact ...

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    22. The role of axial resolution of optical coherence tomography on the measurement of corneal and epithelial thicknesses

      The role of axial resolution of optical coherence tomography on the measurement of corneal and epithelial thicknesses

      Purpose: Our purpose was to investigate the role of the axial resolution of optical coherence tomography on the measurement of corneal and epithelial thickness by evaluating the repeatability and agreement among different optical coherence tomography (OCT) devices with different axial resolutions. Methods: Twenty right eyes of 20 healthy subjects (age: 22.3 ± 1.3 years) and 18 eyes of 18 patients (age: 25.7 ± 6.8 years) after laser in situ keratomileusis (LASIK) refractive surgery were tested. Each subject was imaged using four OCT devices: ultra-high resolution OCT (UHR-OCT), ultra-long scan depth OCT (UL-OCT), commercial RTVue and Visante. The OCT ...

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    23. Scheimpflug–Placido topographer and optical low-coherence reflectometry biometer: Repeatability and agreement

      Scheimpflug–Placido topographer and optical low-coherence reflectometry biometer: Repeatability and agreement

      Purpose To assess the repeatability of common measurements with the Sirius Scheimpflug–Placido topographer and Lenstar LS900 optical low-coherence reflectometry (OLCR) biometer and the limits of agreement (LoA) between the devices. Setting Eye Hospital of Wenzhou Medical College, Wenzhou, China. Design Comparative evaluation of a diagnostic test or technology. Methods One randomly healthy eye of subjects was scanned 3 times with both devices. The parameters assessed were central corneal thickness (CCT), anterior chamber depth (ACD) from the corneal epithelium and from the endothelium, mean keratometry (K), and white-to-white (WTW) corneal diameter. The repeatability of scans was calculated using the within-subject ...

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    24. Automatic Segmentation of the Central Epithelium Imaged With Three Optical Coherence Tomography Devices

      Automatic Segmentation of the Central Epithelium Imaged With Three Optical Coherence Tomography Devices

      Purpose: The aim of this study was to investigate the feasibility of automatic segmentation of the central corneal thickness (CCT) and epithelial thickness (ET) of the human cornea obtained with different spectral domain optical coherence tomography (OCT) instruments. Methods: Ten left eyes from 10 healthy subjects with a mean age of 22.5+/-1.5 years participated in this study. A custom-built ultra-high resolution OCT (UHR-OCT) with a 3-[mu]m axial resolution, ultralong scan depth OCT (UL-OCT) with a 7.5-[mu]m resolution, and commercial RTVue OCT with a 5-[mu]m resolution were used to image the ...

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