1. Articles from Meixiao Shen

    1-24 of 49 1 2 »
    1. Modeling of gonioscopic anterior chamber angle grades based on anterior segment optical coherence tomography

      Modeling of gonioscopic anterior chamber angle grades based on anterior segment optical coherence tomography

      Background To quantitatively assess anterior chamber angle (ACA) structure by anterior segment optical coherence tomography (AS-OCT) and develop a model to evaluate angle width as defined by gonioscopy. Methods The ACAs of each quadrant were evaluated by gonioscopy, classified by the Scheie grading system, and assigned into one of the three grades: small angle (SA), moderate angle (MA), and large angle (LA). The eyes were imaged by AS-OCT, and ACA structural parameters including angle opening distance at the scleral spur (AODSS) and at 750 μm anterior to the scleral spur (AOD750), trabecular-iris space area at 750 μm anterior to the ...

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    2. Assessment of corneal viscoelasticity using elastic wave optical coherence elastography

      Assessment of corneal viscoelasticity using elastic wave optical coherence elastography

      The corneal viscoelasticity have great clinical significance, such as the early diagnosis of keratoconus. In this work, an analysis method which utilized the elastic wave velocity, frequency and energy attenuation to assess the corneal viscoelasticity is presented. Using phase‐resolved optical coherence tomography, the spatial‐temporal displacement map is derived. The phase velocity dispersion curve and center frequency are obtained by transforming the displacement map into the wavenumber‐frequency domain through the 2D Fast Fourier Transform (FFT). The shear modulus is calculated through Rayleigh wave equation using the phase velocity in the high‐frequency. The normalized energy distribution is plotted ...

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    3. In vivo evaluation of corneal biomechanical properties by optical coherence elastography at different cross-linking irradiances

      In vivo evaluation of corneal biomechanical properties by optical coherence elastography at different cross-linking irradiances

      Corneal collagen cross-linking (CXL) strengthens the biomechanical properties of damaged corneas. Quantifying the changes of stiffness due to different CXL protocols is difficult, especially in vivo . A noninvasive elastic wave-based optical coherence elastography system was developed to construct in vivo corneal elasticity maps by excitation of air puff. Biomechanical differences were compared for rabbit corneas given three different CXL protocols while keeping the total energy delivered constant. The Young’s modulus was weaker in corneas treated with higher irradiance levels over shorter durations, and a slight increase of Young’s modulus was present in all groups one week after the ...

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    4. Deep learning based early stage diabetic retinopathy detection using optical coherence tomography

      Deep learning based early stage diabetic retinopathy detection using optical coherence tomography

      Diabetic retinopathy (DR) is one of the leading causes of preventable blindness globally. Performing retinal examinations on all diabetic patients is an unmet need, and detection at an early stage can provide better control of the disease. The objective of this study is to provide an optical coherence tomography (OCT) image based diagnostic technology for automated early DR diagnosis, including at both grades 0 and 1. This work can help ophthalmologists with evaluation and treatment, reducing the rate of vision loss, and enabling timely and accurate diagnosis. In this work, we developed and evaluated a novel deep network – OCTD_Net, for ...

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    5. Precise delineation and tumor localization based on novel image registration strategy between optical coherence tomography and computed tomography in the radiotherapy of intraocular cancer

      Precise delineation and tumor localization based on novel image registration strategy between optical coherence tomography and computed tomography in the radiotherapy of intraocular cancer

      Radiation-associated toxicities due to sophisticated ocular anatomy and shape variability of organs at risk (OARs) are major concerns during external beam radiation therapy (EBRT) of patients with intraocular cancer. A novel two-step image registration strategy between optical coherence tomography (OCT) and computed tomography (CT) images was proposed and validated to precisely localize the target in the EBRT of patients with intraocular cancer. Specifically, multiple features from OCT and CT images were extracted automatically, then spatial transformation based on thin-plate spline function was performed iteratively to achieve feature alignment between the CT and OCT images. Finally, an exclusive OR (XOR) algorithm ...

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    6. Integrating Handcrafted and Deep Features for Optical Coherence Tomography Based Retinal Disease Classification

      Integrating Handcrafted and Deep Features for Optical Coherence Tomography Based Retinal Disease Classification

      Deep Neural Networks (DNNs) have been widely applied to automatic analysis of medical images for disease diagnosis, and to help human experts by efficiently processing immense amounts of images. While handcrafted feature has been used for eye disease detection or classification since the 1990s, DNN was recently adopted in this area and showed very promising performance. Since handcrafted and deep feature can extract complementary information, we propose in this paper three different integration frameworks to combine handcrafted and deep feature for optical coherence tomography (OCT) image based eye disease classification. In addition, to integrate the handcrafted feature at Input and ...

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    7. 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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    8. Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

      Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

      Purpose . To determine conjunctival overlap over the edge of soft contact lens and to visualize the peripheral postlens tear film (PoLTF) underneath soft contact lenses using ultrahigh-resolution optical coherence tomography (UHR-OCT). Methods . Twenty participants (4 males and 16 females, 23.0 ± 3.7 years) were fitted with two different types of soft contact lenses randomly. The limbus with lens was imaged with the UHR-OCT at the horizontal meridian every two hours up to 6 hours during lens wear. The conjunctival overlap was ranked as the percentage of the edge covered by the conjunctiva. The frequency of occurrence for visualized peripheral ...

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    9. 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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    10. 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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    11. 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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    12. Reconstruction of 3D surface maps from anterior segment optical coherence tomography images using graph theory and genetic algorithms

      Reconstruction of 3D surface maps from anterior segment optical coherence tomography images using graph theory and genetic algorithms

      Automatic segmentation of anterior segment optical coherence tomography images provides an important tool to aid management of ocular diseases. Previous studies have mainly focused on 2D segmentation of these images. A novel technique capable of producing 3D maps of the anterior segment is presented here. This method uses graph theory and dynamic programming with shape constraint to segment the anterior and posterior surfaces in individual 2D images. Genetic algorithms are then used to align 2D images to produce a full 3D representation of the anterior segment. In order to validate the results of the 2D segmentation comparison is made to ...

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    13. Real-Time Monitoring of Suprachoroidal Space (SCS) Following SCS Injection Using Ultra-High Resolution Optical Coherence Tomography in Guinea Pig Eyes

      Real-Time Monitoring of Suprachoroidal Space (SCS) Following SCS Injection Using Ultra-High Resolution Optical Coherence Tomography in Guinea Pig Eyes

      Purpose. To monitor the change of suprachoroidal space (SCS) using ultra high resolution-optical coherence tomography (UHR-OCT) following SCS injection with different drug formulations. Methods. An amount of 10 or 20 μL of saline or indocyanine green (ICG) or triamcinolone acetonide (TA) suspension (40 or 80 mg/mL) was injected suprachoroidally into the guinea pig eye with a 30-gauge needle. Immediately after injection, the eyes were imaged by UHR-OCT from 60 minutes up to 24 hours. At each time point, the SCS area on each OCT cross-section was measured in pixels with Image J and the area change from the baselines ...

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    14. 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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    15. 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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    16. 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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    17. 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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    18. 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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    19. 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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    20. 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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    21. 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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    22. 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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    23. Versatile optical coherence tomography for imaging the human eye

      Versatile optical coherence tomography for imaging the human eye

      We demonstrated the feasibility of a CMOS-based spectral domain OCT (SD-OCT) for versatile ophthalmic applications of imaging the corneal epithelium, limbus, ocular surface, contact lens, crystalline lens, retina, and full eye in vivo. The system was based on a single spectrometer and an alternating reference arm with four mirrors. A galvanometer scanner was used to switch the reference beam among the four mirrors, depending on the imaging application. An axial resolution of 7.7 μm in air, a scan depth of up to 37.7 mm in air, and a scan speed of up to 70,000 A-lines per second ...

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    24. 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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    1-24 of 49 1 2 »
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    1. (49 articles) Meixiao Shen
    2. (38 articles) Wenzhou Medical College
    3. (36 articles) University of Miami
    4. (36 articles) Jianhua Wang
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    6. (11 articles) Qi Chen
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    Improving image segmentation performance and quantitative analysis via a computer-aided grading methodology for optical coherence tomography retinal image analysis SD-OCT with Prolonged Scan Depth for Imaging the Anterior Segment of the Eye Characterization of soft contact lens edge fitting using ultra-high resolution and ultra-long scan depth optical coherence tomography Topographical thickness of Bowman's layer determined by ultra-high resolution spectral domain optical coherence tomography Extended scan depth optical coherence tomography for evaluating ocular surface shape Ultra-High Resolution Optical Coherence Tomography for Imaging the Anterior Segment of the Eye Broadband superluminescent diode–based ultrahigh resolution optical coherence tomography for ophthalmic imaging Vitreous Seeding in Retinocytoma: Importance of Optical Coherence Tomography Utility of Spectral-Domain Optical Coherence Tomography in Differentiating Papilledema From Pseudopapilledema: A Prospective Longitudinal Study Visualizing and quantifying cutaneous microvascular reactivity in humans using optical coherence tomography: Impaired dilator function in diabetes Optical Coherence Tomography of Outer Retinal Hyper-Reflectivity, Neovascularization and Pigment in Type 2 Macular Telangiectasia Early Detection of Incipient Retinal Pigment Epithelium Atrophy Overlying Drusen with Fundus Autofluorescence vs. Spectral Domain Optical Coherence Tomography