1. Articles from maolong tang

    1-25 of 25
    1. Methods and systems to measure corneal epithelial thickness and power, stromal thickness, subepithelial corneal power and topography for disease diagnosis

      Methods and systems to measure corneal epithelial thickness and power, stromal thickness, subepithelial corneal power and topography for disease diagnosis

      This invention discloses methods and systems for measuring corneal epithelial thickness and power, stromal thickness, subepitheila corneal power and topography. The systems and methods disclosed herein are non-invasive, non-contact and automated imaging methods which preferably makes use of Fourier-domain optical tomography. Also disclosed herein are scanning patterns and image analysis methods for utilizing and analyzing Fourier-domain optical coherence tomography images to obtain information about conical epithelial and stromal properties as well as parameters useful for evaluating the properties. The methods and systems described herein are useful as eye disease diagnostic tools and eye surgery planning tools.

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    2. Distinguishing between contact lens warpage and ectasia: Usefulness of optical coherence tomography epithelial thickness mapping

      Distinguishing between contact lens warpage and ectasia: Usefulness of optical coherence tomography epithelial thickness mapping

      Purpose To distinguish between corneal ectasia and contact lens–related warpage by characteristic patterns on corneal topography and optical coherence tomography (OCT) epithelial thickness maps. Setting Casey Eye Institute, Portland, Oregon, USA. Design Prospective and retrospective case series. Methods Axial and mean power maps were obtained on corneal topography systems. Epithelial thickness maps were generated using RTVue OCT. A sector divider was applied to all maps. The locations of the minimum epithelial thickness, maximum epithelial thickness, maximum axial power, and maximum mean power were determined based on sector averages. Agreement was defined as the extremums occurring in the same or ...

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    3. Comparison of Newer IOL Power Calculation Methods for Eyes With Previous Radial Keratotomy

      Comparison of Newer IOL Power Calculation Methods for Eyes With Previous Radial Keratotomy

      Purpose : To evaluate the accuracy of the optical coherence tomography–based (OCT formula) and Barrett True K (True K) intraocular lens (IOL) calculation formulas in eyes with previous radial keratotomy (RK). Methods : In 95 eyes of 65 patients, using the actual refraction following cataract surgery as target refraction, the predicted IOL power for each method was calculated. The IOL prediction error (PE) was obtained by subtracting the predicted IOL power from the implanted IOL power. The arithmetic IOL PE and median refractive PE were calculated and compared. Results : All formulas except the True K produced hyperopic IOL PEs at 1 ...

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    4. Imaging the anterior eye with dynamic-focus swept-source optical coherence tomography.

      Imaging the anterior eye with dynamic-focus swept-source optical coherence tomography.

      A custom-built dynamic-focus swept-source optical coherence tomography (SS-OCT) system with a central wavelength of 1310 nm was used to image the anterior eye from the cornea to the lens. An electrically tunable lens was utilized to dynamically control the positions of focusing planes over the imaging range of 10 mm. The B-scan images were acquired consecutively at the same position but with different focus settings. The B-scan images were then registered and averaged after filtering the out-of-focus regions using a Gaussian window. By fusing images obtained at different depth focus locations, high-resolution and high signal-strength images were obtained over the ...

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    5. Corneal Epithelial Remodeling after LASIK Measured by Fourier-Domain Optical Coherence Tomography

      Corneal Epithelial Remodeling after LASIK Measured by Fourier-Domain Optical Coherence Tomography

      Purpose . To quantify corneal epithelial thickness changes after myopic LASIK by OCT. Methods. Epithelial thickness before and after myopic LASIK were measured by a Fourier-domain OCT system. Average central (within 1 mm diameter) and paracentral epithelial thickness (5~6 mm diameter) before and after LASIK were compared. Correlation between central epithelial thickness change and laser spherical equivalent setting was evaluated. An epithelial smoothing constant was estimated based on a mathematical model published previously. Results. Nineteen eyes from 11 subjects were included in the study. Eyes had myopic LASIK ranging from −1.69 D to −6.75 D spherical equivalent. The ...

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    6. Predicting Transepithelial Phototherapeutic Keratectomy Outcomes Using Fourier Domain Optical Coherence Tomography

      Predicting Transepithelial Phototherapeutic Keratectomy Outcomes Using Fourier Domain Optical Coherence Tomography

      PURPOSE:: The aim of this study was to use Fourier domain optical coherence tomography to predict transepithelial phototherapeutic keratectomy outcomes. METHODS:: This is a prospective case series. Subjects with anterior stromal corneal opacities underwent an excimer laser phototherapeutic keratectomy (PTK) combined with a photorefractive keratectomy using the VISX S4 excimer laser (AMO, Inc, Santa Ana, CA). Preoperative and postoperative Fourier domain optical coherence tomography images were used to develop a simulation algorithm to predict treatment outcomes. Main outcome measures included preoperative and postoperative uncorrected distance visual acuities and corrected distance visual acuity. RESULTS:: Nine eyes of 8 patients were treated ...

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    7. Keratoconus diagnosis with optical coherence tomography–based pachymetric scoring system

      Keratoconus diagnosis with optical coherence tomography–based pachymetric scoring system

      Purpose To develop an optical coherence tomography (OCT) pachymetry map–based keratoconus risk scoring system. Settings Doheny Eye Institute, University of Southern California, Los Angeles, California, and Brass Eye Center, New York, New York, USA; Department of Ophthalmology, Affiliated Eye Hospital of Wenzhou Medical College, Wenzhou, China. Design Cross-sectional study. Methods Fourier-domain OCT was used to acquire corneal pachymetry maps in normal and keratoconus subjects. Pachymetric variables were minimum, minimum−median, superior–inferior (S–I), superonasal–inferotemporal (SN–IT), and the vertical location of the thinnest cornea (Ymin). A logistic regression formula and a scoring system were developed based on ...

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    8. OPTICAL COHERENCE TOMOGRAPHY–BASED CORNEAL POWER MEASUREMENT AND INTRAOCULAR LENS POWER CALCULATION FOLLOWING LASER VISION CORRECTION (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

      OPTICAL COHERENCE TOMOGRAPHY–BASED CORNEAL POWER MEASUREMENT AND INTRAOCULAR LENS POWER CALCULATION FOLLOWING LASER VISION CORRECTION (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

      power in cataract surgeries after laser vision correction. Methods: Patients with previous myopic laser vision corrections were enrolled in this prospective study from two eye centers. Corneal thickness and power were measured by Fourier-domain OCT. Axial length, anterior chamber depth, and automated keratometry were measured by a partial coherence interferometer. An OCT-based IOL formula was developed. The mean absolute error of the OCT-based formula in predicting postoperative refraction was compared to two regression-based IOL formulae for eyes with previous laser vision correction. Results: Forty-six eyes of 46 patients all had uncomplicated cataract surgery with monofocal IOL implantation. The mean arithmetic ...

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    9. Use of fourier-domain optical coherence tomography to evaluate anterior stromal opacities in donor corneas

      Use of fourier-domain optical coherence tomography to evaluate anterior stromal opacities in donor corneas

      Purpose . To evaluate Fourier-domain optical coherence tomography (FD-OCT) as an adjunct to traditional slit lamp examination of donor corneas with suspected Anterior Stromal Opacities. Methods . Seven corneas suspected of having anterior stromal opacities by slit lamp examination were evaluated with FD-OCT. Each cornea was evaluated to confirm the presence of opacity and, if present, the depth of opacity was measured. Results . The opacity depth ranged from 82  μ m to 624  μ m. The initial slit lamp impressions of five of the seven corneas were confirmed by OCT. In two corneas, the OCT findings were different from the initial slit lamp impressions ...

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    10. Evaluating DSAEK Graft Deturgescence in Preservation Medium After Microkeratome Cut With Optical Coherence Tomography

      Evaluating DSAEK Graft Deturgescence in Preservation Medium After Microkeratome Cut With Optical Coherence Tomography

      Purpose: To evaluate the Descemet stripping automated endothelial keratoplasty (DSAEK) graft deturgescence in preservation medium after microkeratome cut using Fourier domain optical coherence tomography. Methods: The central and peripheral thickness of DSAEK grafts was measured by Fourier domain optical coherence tomography immediately after microkeratome cuts and 1, 2, 3, and 4 hours afterward. All measurements were taken when the grafts were stored in 4[degrees]C preservation medium. The hourly change in central graft thickness and graft shape (peripheral graft thicknes - central graft thickness) was calculated and tracked over time. Results: Five DSAEK grafts were measured. The average central graft ...

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    11. Pilot Study for OCT Guided Design and Fit of a Prosthetic Device for Treatment of Corneal Disease

      Pilot Study for OCT Guided Design and Fit of a Prosthetic Device for Treatment of Corneal Disease

      Purpose . To assess optical coherence tomography (OCT) for guiding design and fit of a prosthetic device for corneal disease. Methods . A prototype time domain OCT scanner was used to image the anterior segment of patients fitted with large diameter (18.5–20 mm) prosthetic devices for corneal disease. OCT images were processed and analyzed to characterize corneal diameter, corneal sagittal height, scleral sagittal height, scleral toricity, and alignment of device. Within-subject variance of OCT-measured parameters was evaluated. OCT-measured parameters were compared with device parameters for each eye fitted. OCT image correspondence with ocular alignment and clinical fit was assessed. Results ...

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    12. Anterior Chamber Angle Measurements Using Schwalbe's Line With High-resolution Fourier-Domain Optical Coherence Tomography

      Anterior Chamber Angle Measurements Using Schwalbe's Line With High-resolution Fourier-Domain Optical Coherence Tomography

      Purpose: To use Fourier-domain optical coherence tomography (OCT) to measure the angle opening distance at Schwalbe's line (AOD-SL) and determine its value in anterior chamber angle assessment. Methods: Horizontal scans of the nasal and temporal anterior chamber angles in glaucoma subjects were performed at 830 nm wavelength Fourier-domain OCT. Images were graded by 2 ophthalmologists who assessed the visibility of Schwalbe's line (SL), anterior limbus (AL), scleral spur (SS), and angle recess (AR). AOD-SL was measured with computer calipers. SL was manually identified by the termination of the corneal endothelium. Gonioscopy was used to classify anterior chamber angles ...

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    13. Intraocular lens power calculation after previous myopic laser vision correction based on corneal power measured by Fourier-domain optical coherence tomography

      Intraocular lens power calculation after previous myopic laser vision correction based on corneal power measured by Fourier-domain optical coherence tomography

      Purpose To use Fourier-domain optical coherence tomography (OCT) to measure corneal power and calculate intraocular lens (IOL) power in cataract surgeries after laser vision correction. Setting Doheny Eye Institute, Los Angeles, California, and Cullen Eye Institute, Houston, Texas, USA. Design Prospective comparative case series. Methods Patients with previous myopic laser vision correction who had monofocal IOL implantation were enrolled. A Fourier-domain OCT system was used to measure corneal power and pachymetry. Axial length and anterior chamber depth were measured with partial coherence biometry. An OCT-based IOL formula was developed, and the mean absolution error (MAE) of postoperative refraction was compared ...

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    14. Anterior Segment Dimensions in Asian and Caucasian Eyes Measured by Optical Coherence Tomography

      Anterior Segment Dimensions in Asian and Caucasian Eyes Measured by Optical Coherence Tomography

      Please wait Close Window BACKGROUND AND OBJECTIVE: To compare Asian and Caucasian anterior segment dimensions measured by optical coherence tomography (OCT). PATIENTS AND METHODS: Anterior segment OCT images were obtained in normal subjects. Four line scans were acquired at the 90°, 45°, 0°, and 135° meridians of each eye. Computer calipers acquired anterior segment dimensions of corneal diameter, anterior chamber width, corneal vault, and anterior chamber depth on OCT images. Univariate and multivariate analyses were performed to assess correlations. RESULTS: Corneal diameter was 0.5 mm narrower ( P < .01), anterior chamber width was 0.46 mm narrower ( P < .01), and corneal vault was 0.22 mm lower ( P < .01) in Asian eyes. All anterior segment dimensions decreased with age. CONCLUSION: Asian eyes had smaller anterior segments compared to Caucasian eyes. Regardless of race, anterior segment dimensions were smaller in older subjects. Age-related changes may affect the tolerability of long-term implants such as phakic intraocular lenses.

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    15. Intraocular lens power calculation after myopic and hyperopic laser vision correction using optical coherence tomography

      Intraocular lens power calculation after myopic and hyperopic laser vision correction using optical coherence tomography

      Purpose To use optical coherence tomography (OCT) to measure corneal power and calculate intraocular lens (IOL) power in cataract surgeries after myopic and hyperopic laser vision correction (LVC). Methods Patients with previous LVC were enrolled in this prospective study at two centers (Doheny Eye Institute, Los Angeles, CA, USA and Cullen Eye Institute, Houston, TX, USA). Corneal power was measured with a Fourier-domain OCT system. The intravisit repeatability of OCT corneal power measurement was evaluated by the pooled standard deviation of repeat scans. Axial length, anterior chamber depth, and automated keratometry were measured with the IOLMaster. An OCT-based IOL formula ...

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    16. Measurements of Microkeratome Cuts in Donor Corneas With Ultrasound and Optical Coherence Tomography

      Measurements of Microkeratome Cuts in Donor Corneas With Ultrasound and Optical Coherence Tomography
      Purpose: To evaluate optical coherence tomography (OCT) in the measurement of donor corneas in preparation for endothelial keratoplasty. Methods: Donor corneas were imaged by OCT while immersed in preservation medium. Central corneal thickness (CCT) was measured by OCT from the Bowman layer to the endothelium. The corneas were then mounted on an artificial anterior chamber, and the epithelium was removed. Ultrasound pachymetry (USP) was used to measure CCT just before sectioning with a microkeratome. The central graft thickness (CGT) was measured by USP. The graft was then returned to the medium and imaged by OCT. Results: The study included 154 ...
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    17. Investigation of Femtosecond Laser–Enabled Keratoplasty Wound Geometry Using Optical Coherence Tomography

      Investigation of Femtosecond Laser–Enabled Keratoplasty Wound Geometry Using Optical Coherence Tomography

      Purpose: To measure the wound geometry after femtosecond laser-enabled keratoplasty (FLEK) using optical coherence tomography (OCT). Design: Prospective nonrandomized clinical study and laboratory study. Participants: Patients who were candidates for penetrating keratoplasty at an academic referral center. Methods: Wound architecture was measured and analyzed by OCT in 8 eyes of 8 consecutive patients who underwent FLEK. Femtosecond laser lamellar cuts were performed on 3 eye bank corneas, and the wound diameters were measured by OCT. Results: Sutures were completely removed on average at 1 month per decade of age after surgery. No cases of wound dehiscence were noted, and graft-host ...

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    18. Repeatability of laser in situ keratomileusis flap thickness measurement by Fourier-domain optical coherence tomography

      Repeatability of laser in situ keratomileusis flap thickness measurement by Fourier-domain optical coherence tomography

      Purpose: To evaluate the repeatability of Fourier-domain optical coherence tomography (OCT) measurements of the thickness of femtosecond laser–created laser in situ keratomileusis (LASIK) flaps.Setting: Doheny Eye Institute, University of Southern California, Los Angeles, California, USA.Design: Case series, evaluation of diagnostic technology.Methods: In this consecutive series, Fourier-domain OCT (RTVue) was used to measure flap thickness 1 week after LASIK. Flaps were created with a Pulsion 60 kHz femtosecond laser programmed for 110 μm flap thickness. Each eye was scanned 2 times with a radial pachymetry pattern and 1 time with a horizontal line scan. Flap thicknesses were ...

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    19. Corneal power measurement with Fourier-domain optical coherence tomography

      Corneal power measurement with Fourier-domain optical coherence tomography
      Setting Doheny Eye Institute, Los Angeles, California, USA. Design Cross-sectional study. Methods A Fourier-domain OCT system (RTVue) was used to scan normal eyes, eyes after myopic laser in situ keratomileusis (LASIK), and keratoconic eyes. After the corneal surfaces were delineated, the system calculated anterior and posterior corneal powers by curve fitting over the central 3.0 mm diameter area. Net corneal power was calculated using a thick-lens formula. The repeatability of the calculations was evaluated by the pooled standard deviation of 3 measurements from the same visit. The net corneal power values were compared with standard automated keratometry measurements (IOLMaster ...
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    20. Pachymetric mapping with Fourier-domain optical coherence tomography

      Pachymetric mapping with Fourier-domain optical coherence tomography

      Purpose To evaluate the repeatability of Fourier-domain optical coherence tomography (OCT) pachymetric mapping and compare central corneal thickness (CCT) measurements by OCT, ultrasound pachymetry, and scanning-slit tomography. Setting Doheny Eye Institute, University of Southern California, Los Angeles, California, USA. Methods A Fourier-domain OCT system was used to map the corneal thickness in normal eyes with scans centered on the corneal vertex or the pupil. Repeatability of central and pericentral map sectors was assessed by pooled standard deviation. The CCT measurements were compared between the OCT, ultrasound, and scanning-slit devices. Results Pupil centration (SD: 1.3 μm central, 1.8 to ...

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    21. Reproducibility of Tear Meniscus Measurement by Fourier-Domain Optical Coherence Tomography: A Pilot Study

      BACKGROUND AND OBJECTIVE To study the reproducibility of tear meniscus measurement with high-speed high-resolution Fourier-domain optical coherence tomography (FD-OCT). PATIENTS AND METHODS Twenty normal participants were enrolled in this prospective study. The lower tear meniscus in the right eye of each subject was imaged by vertical scans centered on the inferior cornea and the lower eyelid using an FD-OCT system (RTVue; Optovue, Inc., Fremont, CA) with a corneal adaptor. The system performs 26,000 axial scans per second and has a 5-micron axial resolution. Each subject was examined at two visits 30 to 60 days apart. Each eye was scanned ...
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    22. Gaussian fitting on mean curvature maps of parameterization of corneal ectatic diseases

      The present invention discloses a method for characterizing ectatic diseases of the cornea by computing a mean curvature map of the anterior or posterior surfaces of the cornea and fitting the map to a Gaussian function to characterize the surface features of the map. Exemplary ectatic disease that may be characterized include keratoconus and pellucid marginal degeneration. Also disclosed are a system for diagnosing ectatic disease of the cornea and a computer readable medium encoding the method thereof.
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    23. Keratoconus Diagnosis with Optical Coherence Tomography Pachymetry Mapping

      Objective To detect abnormal corneal thinning in keratoconus using pachymetry maps measured by high-speed anterior segment optical coherence tomography (OCT). Design Cross-sectional observational study. Participants Thirty-seven keratoconic eyes from 21 subjects and 36 eyes from 18 normal subjects. Methods The OCT system operated at a 1.3 μm wavelength with a scan rate of 2000 axial scans per second. A pachymetry scan pattern (8 radials, 128 axial scans each; 10 mm diameter) centered at the corneal vertex was used to map the corneal thickness. The pachymetry map was divided into zones by octants and annular rings. Five pachymetric parameters were ...
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    24. High-resolution Imaging of Complicated LASIK Flap Interface Fluid Syndrome

      The authors report a case of post-LASIK interface fluid syndrome that led to epithelial ingrowth, a sequelae that had not been reported to date. The interface fluid was caused by steroid-induced ocular hypertension. On post-LASIK day 49, the interface fluid, epithelial ingrowth, and noncellular reflective deposits were visualized by confocal microscopy and high-resolution Fourier-domain optical coherence tomography. No inflammatory cells or infectious organisms were seen. These high-resolution imaging technologies were useful in the noninvasive evaluation of the location and nature of flap interface pathologies at the microstructural level. [Ophthalmic Surg Lasers Imaging; 2008;39: S80-S82.]
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    25. Optical coherence tomography of clear corneal incisions for cataract surgery

      Purpose To study the architecture of clear corneal incisions for phacoemulsification cataract surgery using optical coherence tomography (OCT). Setting Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA. Methods This prospective study comprised 20 eyes of 20 patients 1 month after cataract surgery performed by 1 of 2 experienced surgeons. Temporal clear corneal single-plane incisions were made with 3.0 mm metal keratomes. Each eye was scanned before and 1 month after surgery with a prototype high-speed anterior segment OCT system (Carl Zeiss Meditec, Inc.). The OCT scans ...
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    1-25 of 25
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    Pachymetric mapping with Fourier-domain optical coherence tomography Corneal power measurement with Fourier-domain optical coherence tomography Repeatability of laser in situ keratomileusis flap thickness measurement by Fourier-domain optical coherence tomography Intraocular lens power calculation after myopic and hyperopic laser vision correction using optical coherence tomography Anterior Segment Dimensions in Asian and Caucasian Eyes Measured by Optical Coherence Tomography Intraocular lens power calculation after previous myopic laser vision correction based on corneal power measured by Fourier-domain optical coherence tomography Anterior Chamber Angle Measurements Using Schwalbe's Line With High-resolution Fourier-Domain Optical Coherence Tomography Influence of scan direction on subfoveal choroidal vascularity index using optical coherence tomography Subthreshold Nanosecond Laser for Non-resolving Central Serous Chorioretinopathy: A Double-masked Sham-controlled Randomised Trial Optical Coherence Tomography Angiography (OCTA) to Assess Cardiac Output and Cerebral Perfusion at the Time of Children's Cardiac Surgery Recent advances in optical coherence tomography for anterior segment imaging in small animals and their clinical implications Intraoperative optical coherence tomography-guided donor corneal tissue assessment and preparation