1. Articles from Jodhbir S. Mehta

    1-24 of 28 1 2 »
    1. Objective Imaging Diagnostics for Dry Eye Disease

      Objective Imaging Diagnostics for Dry Eye Disease

      Traditional diagnostic tests for dry eye disease (DED), such as fluorescein tear film break-up time and the Schirmer test, are often associated with poor reproducibility and reliability, which make the diagnosis, follow-up, and management of the disease challenging. Advances in ocular imaging technology enables objective and reproducible measurement of changes in the ocular surface, tear film, and optical quality associated with DED. In this review, the authors will discuss the application of various imaging techniques, such as, noninvasive tear break-up time, anterior segment optical coherence tomography, in vivo confocal microscopy, meibography, interferometry, aberrometry, thermometry, and tear film imager in DED ...

      Read Full Article
    2. Optical Coherence Tomography Angiography Imaging to monitor Anti-VEGF treatment of Corneal Vascularization in a Rabbit Mode

      Optical Coherence Tomography Angiography Imaging to monitor Anti-VEGF treatment of Corneal Vascularization in a Rabbit Mode

      Optical coherence tomography angiography (OCTA) is a well-established non-invasive retinal vascular imaging technique. It has been recently adapted to image the anterior segment and has shown good potential to image corneal vascularisation. The purpose of the study is to evaluate the usefulness of OCTA to monitor regression of corneal vessels following anti-VEGF (vascular endothelial growth factor) treatment using a previously established corneal vascularisation rabbit model. The regression of vessels following the treatment with aflibercept and ranibizumab anti-VEGFs using both topical instillation and sub-conjunctival injection was quantified using OCTA and compared with ICGA (indocyanine green angiography). Overall vessel density measurements using ...

      Read Full Article
    3. Optical Coherence Tomography Angiography for Evaluation of Reperfusion following Pterygium Surgery

      Optical Coherence Tomography Angiography for Evaluation of Reperfusion following Pterygium Surgery

      Purpose To describe the use of optical coherence tomography angiography (OCTA) to quantitatively monitor the conjunctival graft revascularization after pterygium excision and conjunctival autograft (CAG) transplantation. Design Prospective, interventional case series. Methods Ten patients undergoing pterygium excision and femtosecond laser-assisted CAG transplantation were included. OCTA was performed at 1 week, 1 and 3 months postoperatively at the CAG transplantation site and harvested area. The vessel density at three different depths: conjunctival epithelium or CAG epithelium, conjunctival stroma or CAG stroma, and episclera, was evaluated and quantified. The revascularization rate was assessed and correlated with the postoperative CAG thickness. Results No ...

      Read Full Article
    4. Optical coherence tomography angiography for the anterior segment

      Optical coherence tomography angiography for the anterior segment

      Optical coherence tomography angiography (OCTA) is a rapid and non-invasive technique for imaging vasculature in the eye. As OCTA can produce high-resolution cross-sectional images and allow depth-resolved analysis for accurate localization of pathology of interest, it has become a promising method for anterior segment imaging. Furthermore, OCTA offers a more patient-friendly alternative to the conventional invasive dye-based fluorescent angiography. However, conventional OCTA systems are typically designed and optimized for the posterior segment of the eye, and thus using OCTA for anterior segment imaging can present several difficulties and limitations. In this review, we summarized the recent developments and clinical applications ...

      Read Full Article
    5. Vessel density and En-face segmentation of optical coherence tomography angiography to analyse corneal vascularisation in an animal model

      Vessel density and En-face segmentation of optical coherence tomography angiography to analyse corneal vascularisation in an animal model

      Background Optical coherence tomography angiography (OCTA) is a novel non-invasive angiography technology that has recently been extensively studied for its utility in anterior segment imaging. In this study, we compared a split-spectrum amplitude decorrelation angiography (SSADA) OCTA and an optical micro-angiography (OMAG SD) OCTA system to current angiographic technique, indocyanine green angiography (ICGA), to assess corneal vascularisation in an animal model. Methods We imaged 16 rabbits, (one eye per animal) with corneal vascularisation using SSADA OCTA (AngioVue; Optovue Inc., USA), OMAG OCTA (Angioscan; RS-3000 Nidek Co. Ltd., Japan) and ICGA in the same region of interest of the cornea at ...

      Read Full Article
    6. Intraoperative Optical Coherence Tomography–Guided Femtosecond Laser–Assisted Deep Anterior Lamellar Keratoplasty

      Intraoperative Optical Coherence Tomography–Guided Femtosecond Laser–Assisted Deep Anterior Lamellar Keratoplasty

      Purpose: To describe the feasibility and outcomes of intraoperative optical coherence tomography (OCT)–guided, femtosecond laser –assisted deep anterior lamellar keratoplasty in which the lamellar and tunnel cuts were completed by laser. Methods: The Ziemer Z8 system was used to scan the corneas intraoperatively and guide the stromal lamellar and tunnel cuts created by the laser. Thirty porcine eyes and 3 human cadaver globes were used to evaluate the accuracy of laser-created intrastromal tunnels and the feasibility of achieving big-bubble pneumatic dissection. The tunnel distance above the Descemet membrane ( D t-dm ) was set at 100 and 130 μm, and the ...

      Read Full Article
    7. Quantification of the Posterior Cornea Using Swept Source Optical Coherence Tomography

      Quantification of the Posterior Cornea Using Swept Source Optical Coherence Tomography

      Purpose : We define optical coherence tomography (OCT) measurement parameters of the corneal endothelium/Descemet's membrane (DM) complex and peripheral transition zone (TZ) and describe these measurements in an ethnically Chinese population. Methods : OCT images of the anterior segment and iridocorneal angle were obtained from 129 healthy Chinese subjects (129 eyes), aged 40 to 81 years. The scleral spur (SS) and Schwalbe's line (SL) were identified in each image. Endothelium/DM diameter, referred to as endothelial arc length (EAL), is the SL-to-SL distance. The SS-to-SL distance encompasses the TZ and trabecular meshwork (TM). Since the TZ cannot be visualized ...

      Read Full Article
    8. Comparison of Optical Coherence Tomography Angiography to Indocyanine Green Angiography and Slit Lamp Photography for Corneal Vascularization in an Animal Model

      Comparison of Optical Coherence Tomography Angiography to Indocyanine Green Angiography and Slit Lamp Photography for Corneal Vascularization in an Animal Model

      Corneal neovascularization (CoNV) could be treated by novel anti-angiogenic therapies, though reliable and objective imaging tools to evaluate corneal vasculature and treatment efficacy is still lacking. Optical coherence tomography angiography (OCTA) –currently designed as a retinal vascular imaging system— has been recently adapted for anterior-segment and showed good potential for successful imaging of CoNV. However, further development requires an animal model where parameters can be studied more carefully with histological comparison. Our study evaluated the OCTA in suture-induced CoNV in a rabbit model compared to indocyanine green angiography (ICGA) and slit-lamp photography (SLP). Overall vessel density measurements from OCTA showed ...

      Read Full Article
    9. Novel application of In Vivo Micro-Optical Coherence Tomography to assess Cornea scarring in an Animal Model

      Novel application of In Vivo Micro-Optical Coherence Tomography to assess Cornea scarring in an Animal Model

      This pilot study uses a micro-optical coherence tomography (micro-OCT) system with ~1 μm axial resolution specifically to image the cornea and corneal scars in vivo . We used an established murine corneal scar model by irregular phototherapeutic keratectomy in ten C57BL/6 mice, with serial imaging using the micro-OCT and compared to anterior segment (AS-OCT) (RTvue, Optovue, Fremont, CA) before and after scar induction. Main outcome was agreement between the AS-OCT and micro-OCT using Bland-Altman plots (95% limits of agreement, LoA).We analysed 10 control eyes and 10 eyes with corneal scars and found that there was good agreement between AS-OCT ...

      Read Full Article
    10. Intraoperative Optical Coherence Tomography Vault Measurement in Posterior Chamber Phakic Intraocular Lens Implantation

      Intraoperative Optical Coherence Tomography Vault Measurement in Posterior Chamber Phakic Intraocular Lens Implantation

      PURPOSE: To describe the use of intraoperative optical coherence tomography (OCT) vault measurement in 5 cases of posterior chamber phakic intraocular lens (IOL) implantation. METHODS: This case series included 5 eyes in 3 consecutive patients undergoing phakic IOL implantation. RTVue OCT (Optovue, Inc., Fremont, CA) was used to obtain intraoperative vault measurements after pupil constriction. Visante OCT (Carl Zeiss Meditec, Jena, Germany) was used to obtain postoperative vault measurements. RESULTS: Intraoperative vault measurements ranged from 228 to 1,060 µ m. There were no postoperative complications. Postoperative OCT vault measurements ranged from 230 to 670 µ m. CONCLUSIONS: Intraoperative OCT can be ...

      Read Full Article
    11. Needle Depth and Big-Bubble Success in Deep Anterior Lamellar Keratoplasty: An Ex Vivo Microscope-Integrated OCT Study

      Needle Depth and Big-Bubble Success in Deep Anterior Lamellar Keratoplasty: An Ex Vivo Microscope-Integrated OCT Study

      Purpose: To examine big-bubble (BB) formation success rates in deep anterior lamellar keratoplasty (DALK) at various corneal depths using real-time guidance from swept-source, microscope-integrated optical coherence tomography (SS-MIOCT). Methods: The DALK procedure was performed ex vivo with 34 human donor corneoscleral buttons on pressurized artificial anterior chambers using the BB technique employed by Anwar and Teichmann. We inserted a needle under controlled ex vivo conditions to corneal depths ranging from 40% to ≥90% using real-time guidance from SS-MIOCT and injected air. BB success was then determined for each injection. Results: The average needle depth for successful full BB formation was ...

      Read Full Article
    12. Applications of Anterior Segment Optical Coherence Tomography in Cornea and Ocular Surface Diseases

      Applications of Anterior Segment Optical Coherence Tomography in Cornea and Ocular Surface Diseases

      Optical coherence tomography (OCT) is a noncontact technology that produces high-resolution cross-sectional images of ocular tissues. Anterior segment OCT (AS-OCT) enables the precise visualization of anterior segment structure; thus, it can be used in various corneal and ocular surface disorders. In this review, the authors will discuss the application of AS-OCT for diagnosis and management of various corneal and ocular surface disorders. Use of AS-OCT for anterior segment surgery and postoperative management will also be discussed. In addition, application of the device for research using human data and animal models will be introduced.

      Read Full Article
    13. Evaluation of a Micro-Optical Coherence Tomography for the Corneal Endothelium in an Animal Model

      Evaluation of a Micro-Optical Coherence Tomography for the Corneal Endothelium in an Animal Model

      Recent developments in optical coherence tomography (OCT) systems for the cornea have limited resolution or acquisition speed. In this study we aim to evaluate the use of a ‘micro-OCT’ (μOCT ~1 μm axial resolution) compared to existing imaging modalities using animal models of corneal endothelial disease. We used established cryoinjury and bullous keratopathy models in Sprague Dawley rats comparing ex vivo μOCT imaging in normal and diseased eyes to (1) histology; (2) in vivo confocal microscopy (IVCM); and (3) scanning electron microscopy (SEM). Qualitative and quantitative comparisons amongst imaging modalities were performed using mean endothelial cell circularity [(4π × Area)/Perimeter ...

      Read Full Article
    14. Intraobserver repeatability and interobserver reproducibility of corneal measurements in normal eyes using an optical coherence tomography–Placido disk device

      Intraobserver repeatability and interobserver reproducibility of corneal measurements in normal eyes using an optical coherence tomography–Placido disk device

      Purpose To study intraobserver and interobserver reproducibility of corneal topography and aberrometry measurements using a device combining optical coherence tomography (OCT) and a Placido disk (Visante Omni). Setting Singapore National Eye Centre, Singapore. Design Prospective nonrandomized study. Method Measurements of simulated keratometry (K), anterior mean curvature, spherical anterior and posterior elevations, 4.5 mm diameter zone aberrometry (spherical aberration, asphericity, astigmatism), pachymetry, and white-to-white (WTW) diameter were taken in normal right eyes. Mean biases and limits of agreement (LoA) were obtained using Bland-Altman analysis. Results Regarding intraobserver repeatability, the mean biases for simulated K, anterior mean curvature, spherical anterior/posterior ...

      Read Full Article
    15. Use of Anterior Segment Optical Coherence Tomography to Predict Corneal Graft Rejection in Small Animal Models

      Use of Anterior Segment Optical Coherence Tomography to Predict Corneal Graft Rejection in Small Animal Models

      Purpose: To correlate the degree of anterior chamber (AC) inflammation and corneal thickness evaluated by anterior segment optical coherence tomography (ASOCT) with corneal graft rejection status and to explore the value of ASOCT in assisting the diagnosis or prediction of graft rejection using a rat penetrating keratoplasty (PK) model. Methods: A total of 40 PKs were performed using Fisher rats (allogeneic groups) and Lewis rats (syngeneic group) as donors and Lewis rats as recipients: isograft control group (n=10), allograft untreated group (n=10), and allograft with 1% prednisolone acetate treatment group (n=20). All the grafts were evaluated for ...

      Read Full Article
    16. Intraoperative Anterior Segment Optical Coherence Tomography: A Novel Assessment Tool during Deep Anterior Lamellar Keratoplasty

      Intraoperative Anterior Segment Optical Coherence Tomography: A Novel Assessment Tool during Deep Anterior Lamellar Keratoplasty

      Purpose To describe the use of high-resolution anterior segment optical coherence tomography (AS-OCT) during deep anterior lamellar keratoplasty (DALK). Design Prospective case series. Methods We performed at the Singapore National Eye Centre sequential intraoperative AS-OCT scans using iVue 100-2 (Optovue, Fremont, CA) during different DALK techniques. Results In case 1 (corneal scarring) the OCT images helped guiding manual dissection, showed the depth of the needle track before air injection, and identified the location of a small bubble when the big-bubble failed. In cases 2 (macular dystrophy) and 3 (lattice), visco-dissection was undertaken, but in case 2 the OCT showed the ...

      Read Full Article
    17. Comparison of Anterior Segment Optical Tomography Parameters Measured Using a Semi-Automatic Software to Standard Clinical Instruments

      Comparison of Anterior Segment Optical Tomography Parameters Measured Using a Semi-Automatic Software to Standard Clinical Instruments

      by Marcus Ang, Wesley Chong, Huiqi Huang, Wan Ting Tay, Tien Yin Wong, Ming-Guang He, Tin Aung, Jodhbir S. Mehta Objective To compare anterior segment parameters measured using a semi-automatic software (Zhongshan Angle Assessment Program, ZAP) applied to anterior segment optical coherence tomography (AS-OCT) images, with commonly used instruments. Methods Cross-sectional study of a total of 1069 subjects (1069 eyes) from three population-based studies of adults aged 40–80 years. All subjects underwent AS-OCT imaging and ZAP software was applied to determine anterior chamber depth (ACD), central corneal thickness (CCT), anterior and keratometry (K) – readings. These were compared to auto-refraction ...

      Read Full Article
    18. Reproducibility and age-related changes of ocular parametric measurements in rabbits

      Reproducibility and age-related changes of ocular parametric measurements in rabbits

      Background The rabbit is a common animal model for ophthalmic research, especially corneal research. Ocular structures grow rapidly during the early stages of life. It is unclear when the rabbit cornea becomes mature and stabilized. We investigated the changes of keratometry, refractive state and central corneal thickness (CCT) with age. In addition, we studied the intra- and inter-observer reproducibility of anterior chamber depth (ACD) and anterior chamber width (ACW) measurements in rabbits using anterior segment-optical coherence tomography (AS-OCT). Results The growth of New Zealand White rabbits (n = 16) were monitored from age 1 to 12 months old. Corneal keratometric and ...

      Read Full Article
    19. Refractive lenticule extraction flap and stromal bed morphology assessment with anterior segment optical coherence tomography

      Refractive lenticule extraction flap and stromal bed morphology assessment with anterior segment optical coherence tomography

      Purpose To evaluate the flap and stromal bed after refractive lenticule extraction using optical coherence tomography (OCT). Setting Singapore National Eye Centre, Singapore. Design Longitudinal case series. Methods Horizontal scans (RTVue) were taken preoperatively and after refractive lenticule extraction. Two procedures were performed: femtosecond lenticule extraction and small-incision femtosecond lenticule extraction. Flap and bed thicknesses were measured at the center (0.0 mm) and 1.5 mm and 3.0 mm to either side. Results At 1 week, the mean flap at 0.0 mm was borderline thicker (P=.056) and at +3.0 mm significantly thicker after femtosecond lenticule ...

      Read Full Article
    20. Correlation of anterior segment optical coherence tomography measurements with graft trephine diameter following descemet stripping automated endothelial keratoplasty

      Correlation of anterior segment optical coherence tomography measurements with graft trephine diameter following descemet stripping automated endothelial keratoplasty

      Background To assess repeatability of the Zhongshan Assessment Program (ZAP) software measurement of Anterior Segment Optical Coherence Tomography (ASOCT) images and correlate with graft trephine diameter following Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) Methods Retrospectively evaluated interventional case series. 121 consecutive eyes undergoing DSAEK over a 26 month period underwent ASOCT imaging 1 month after their surgery. ASOCT images were processed using ZAP software which measured the graft and cornea parameters including anterior and posterior graft arc length and cord length, posterior cornea arc length (PCAL) and anterior chamber width. Results The graft measurements showed good repeatability on ASOCT using ...

      Read Full Article
    21. Anterior Chamber Dimensions and Posterior Corneal Arc Length in Malay Eyes: An Anterior segment Optical Coherence Tomography Study

      Anterior Chamber Dimensions and Posterior Corneal Arc Length in Malay Eyes: An Anterior segment Optical Coherence Tomography Study

      Purpose: To provide normative data of corneal and anterior segment dimensions and a novel parameter, PCAL, in an adult Malay population. Methods: The current analysis is a sub-study of the Singapore Malay Eye Study (SiMES), a cross-sectional, population-based study of urban Malays aged 40-80 years. Subjects underwent ophthalmic and systemic examination, including imaging with anterior segment optical coherence tomography (AS-OCT). Ocular parameters were subsequently measured with the Zhongshan Assessment Program (ZAP): Anterior chamber depth (ACD), central corneal thickness (CCT), anterior and posterior corneal curvature (ACC and PCC), and posterior corneal arc length (PCAL), which is a novel parameter defined as ...

      Read Full Article
    22. Intraoperative use of spectral-domain optical coherence tomography during Descemet’s stripping automated endothelial keratoplasty

      Intraoperative use of spectral-domain optical coherence tomography during Descemet’s stripping automated endothelial keratoplasty

      Purpose: To evaluate the intraoperative changes in the donor lenticule, recipient cornea, and the reduction of interface fluid thickness during Descemet’s stripping and automated endothelial keratoplasty with EndoGlide™ (Angiotech Pharmaceuticals Inc, Vancouver, Canada) donor insertion, using intraoperative spectral-domain optical coherence tomography. Methods: Prospective observational case series of patients underwent Descemet’s stripping and automated endothelial keratoplasty using the EndoGlide inserter. Spectral-domain optical coherence tomography (iVue; Optovue Inc, Fremont, CA) with a handheld probe was used to image the cornea and anterior chamber. Standardized software was used to measure interface fluid gap, host cornea, and donor lenticule thicknesses during the ...

      Read Full Article
    23. Anterior Segment Optical Tomography Study of the Cornea and Anterior Segment in Adult Ethnic South Asian Indian Eyes

      Anterior Segment Optical Tomography Study of the Cornea and Anterior Segment in Adult Ethnic South Asian Indian Eyes

      Purpose. To report normative results of anterior segment and corneal biometric parameters and their associations in ethnic South Asian Indian adults. Methods. The Singapore Indian Eye Study (SINDI) is a cross-sectional, population-based study of ethnic South Asian Indians aged 40-80 years. Subjects underwent ophthalmic and systemic examination, including imaging with anterior segment optical coherence tomography (AS-OCT). Parameters were derived using the Zhongshan Assessment Program (ZAP): anterior chamber depth (ACD), central corneal thickness (CCT), anterior and posterior corneal curvatures (ACC and PCC). Posterior corneal arc length (PCAL) is a novel parameter defined as the arc distance between scleral spurs on the ...

      Read Full Article
    24. Reproducibility of Cornea Measurements in Anterior Segment OCT images of Normal Eyes and Eyes with Bullous Keratopathy Analyzed with the Zhongshan Assessment Program (ZAP)

      Reproducibility of Cornea Measurements in Anterior Segment OCT images of Normal Eyes and Eyes with Bullous Keratopathy Analyzed with the Zhongshan Assessment Program (ZAP)

      Purpose: To determine the interobserver and intraobserver measurement reproducibility of cornea parameters of both normal eyes and eyes with bullous keratopathy obtained with the Zhongshan Assessment Program (ZAP, Guangzhou, China) on Anterior segment optical coherence tomography (AS-OCT, Visante; Carl Zeiss Meditec, Dublin, CA) images. Methods: Comparative study of 24 healthy volunteers and 25 subjects with bullous keratopathy (BK). AS-OCT images were independently analyzed by two examiners. Parameters examined: anterior chamber depth (ACD), central corneal thickness (CCT), posterior corneal curvature (PCC) and posterior corneal arc length (PCAL). Interobserver and intraobserver reproducibility of the above parameters was calculated in terms of limits ...

      Read Full Article
    1-24 of 28 1 2 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (28 articles) Jodhbir S. Mehta
    2. (19 articles) Singapore Eye Research Institute
    3. (9 articles) Optovue
    4. (7 articles) National University of Singapore
    5. (5 articles) Duke University
    6. (5 articles) Tin Aung
    7. (5 articles) Carl Zeiss Meditec
    8. (3 articles) Nanyang Technological University
    9. (3 articles) Tien Yin Wong
    10. (2 articles) University of Melbourne
    11. (1 articles) University of Groningen
    12. (1 articles) NinePoint Medical
  3. Popular Articles

  4. Picture Gallery

    Laser in situ keratomileusis flap measurements: Comparison between observers and between spectral-domain and time-domain anterior segment optical coherence tomography Evaluation of Corneal Epithelial Healing Under Contact Lens with Spectral-Domain Anterior Segment Optical Coherence Tomography (SDOCT) Reproducibility of Cornea Measurements in Anterior Segment OCT images of Normal Eyes and Eyes with Bullous Keratopathy Analyzed with the Zhongshan Assessment Program (ZAP) Anterior Segment Optical Tomography Study of the Cornea and Anterior Segment in Adult Ethnic South Asian Indian Eyes Intraoperative use of spectral-domain optical coherence tomography during Descemet’s stripping automated endothelial keratoplasty Anterior Chamber Dimensions and Posterior Corneal Arc Length in Malay Eyes: An Anterior segment Optical Coherence Tomography Study Correlation of anterior segment optical coherence tomography measurements with graft trephine diameter following descemet stripping automated endothelial keratoplasty Refractive lenticule extraction flap and stromal bed morphology assessment with anterior segment optical coherence tomography Long-Term Arterial Remodeling After Bioresorbable Scaffold Implantation 4-Year Follow-up of Quantitative Coronary Angiography, Histology and Optical Coherence Tomography Visualization of Bacterial Colonization and Cellular Layers in a Gut-on-a-Chip System Using Optical Coherence Tomography Optical Coherence Tomography Measurements as Potential Imaging Biomarkers for Parkinson's Disease: A Systematic Review and Meta-analysis Use of ultra-wide field retinal imaging and optical coherence tomography angiography in the diagnosis of incomplete Susac syndrome