1. Articles from Jacqueline Chua

    1-20 of 20
    1. Novel Approaches for Imaging-Based Diagnosis of Ocular Surface Disease

      Novel Approaches for Imaging-Based Diagnosis of Ocular Surface Disease

      Imaging has become indispensable in the diagnosis and management of diseases in the posterior part of the eye. In recent years, imaging techniques for the anterior segment are also gaining importance and are nowadays routinely used in clinical practice. Ocular surface disease is often synonymous with dry eye disease, but also refers to other conditions of the ocular surface, such as Meibomian gland dysfunction or keratitis and conjunctivitis with different underlying causes, i.e., allergies or infections. Therefore, correct differential diagnosis and treatment of ocular surface diseases is crucial, for which imaging can be a helpful tool. A variety of ...

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    2. Stable complex conjugate artifact removal in OCT using circularly polarized light as reference

      Stable complex conjugate artifact removal in OCT using circularly polarized light as reference

      In Fourier domain optical coherence tomography (FDOCT), the depth profile is mirrored about the zero delay between the sample and reference optical paths, limiting the imaging depth to half of the entire ranging space and undermining the optimal sensitivity window. We present a new method, to the best of our knowledge, to remove the complex conjugate artifact by using circularly polarized light as reference. Quadrature detection of the complex fringe is achieved by utilizing the intrinsic

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    3. Are choriocapillaris flow void features robust to diurnal variations? A swept-source optical coherence tomography angiography (OCTA) study

      Are choriocapillaris flow void features robust to diurnal variations? A swept-source optical coherence tomography angiography (OCTA) study

      We evaluated the impact of diurnal variation on choroidal and retinal microvasculature and structural measurements using a swept-source optical coherence tomography angiography machine (SS-OCTA; PLEX Elite 9,000, Carl Zeiss Meditec, Inc., Dublin, USA). Fourteen participants who were without ocular diseases underwent SS-OCTA imaging using 3 × 3-mm 2 macular scan pattern on two separate days at five time points. Choriocapillaris flow voids were generated to determine its density (percentage), size (μm) and numbers. Perfusion densities of the large superficial vessels, as well as capillaries on superficial and deep vascular plexuses were generated from retinal angiograms. Subfoveal choroidal and retinal thicknesses ...

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    4. Prevalence, risk factors and impact of posterior staphyloma diagnosed from wide‐field optical coherence tomography in Singapore adults with high myopia

      Prevalence, risk factors and impact of posterior staphyloma diagnosed from wide‐field optical coherence tomography in Singapore adults with high myopia

      Purpose To investigate the prevalence and risk factors of posterior staphyloma using wide‐field optical coherence tomography (WF‐OCT) in adults with high myopia in Singapore. Design Population‐based cross‐sectional study. Methods Adults with spherical equivalent (SE) ≤ −5D in either eye at the first visit of Singapore Epidemiology of Eye Diseases study and Singapore Prospective Study Program study were recruited. Posterior staphyloma was diagnosed using WF‐OCT (PLEX ® Elite9000, Carl Zeiss Meditec). Myopic macular degeneration (MMD), myopic traction maculopathy (MTM) and vision‐related quality of life (VRQoL) were assessed using fundus photographs, DRI‐Triton OCT (Topcon) and the Impact ...

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    5. Longitudinal Structural and Microvascular Observation in RCS Rat Eyes Using Optical Coherence Tomography Angiography

      Longitudinal Structural and Microvascular Observation in RCS Rat Eyes Using Optical Coherence Tomography Angiography

      Purpose : To evaluate the change of retinal thickness and ocular microvasculature in a rat model of retinitis pigmentosa using swept source optical coherence tomography angiography (SS-OCTA) Methods : Three-weeks-old Royal College of Surgeons (RCS) rats ( n = 8) and age-matched control rats ( n = 14) were imaged by a prototype SS-OCTA system. Follow-up measurements occurred every three weeks on six RCS rats until week 18, and cross-sectional measurements were conducted on control rats. Thicknesses of different retinal layers and the total retina were measured. The enface angiograms from superficial vascular plexiform (SVP) and deep capillary plexiform (DCP) were analyzed, and the image sharpness ...

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    6. Systemic hypertension associated retinal microvascular changes can be detected with optical coherence tomography angiography

      Systemic hypertension associated retinal microvascular changes can be detected with optical coherence tomography angiography

      A major complication of hypertension is microvascular damage and capillary rarefaction is a known complication of hypertensive end-organ damage which confers a higher risk of systemic disease such as stroke and cardiovascular events. Our aim was to study the effect of hypertension on the retinal microvasculature using non-invasive optical coherence tomography angiography (OCTA). We performed a case-control study of 94 eyes of 94 participants with systemic hypertension and 46 normal control eyes from the Singapore Chinese Eye Study using a standardized protocol to collect data on past medical history of hypertension, including the number and type of hypertensive medications and ...

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    7. Optical Coherence Tomography Angiography in Diabetes and Diabetic Retinopathy

      Optical Coherence Tomography Angiography in Diabetes and Diabetic Retinopathy

      Diabetic retinopathy (DR) is a common complication of diabetes mellitus that disrupts the retinal microvasculature and is a leading cause of vision loss globally. Recently, optical coherence tomography angiography (OCTA) has been developed to image the retinal microvasculature, by generating 3-dimensional images based on the motion contrast of circulating blood cells. OCTA offers numerous benefits over traditional fluorescein angiography in visualizing the retinal vasculature in that it is non-invasive and safer; while its depth-resolved ability makes it possible to visualize the finer capillaries of the retinal capillary plexuses and choriocapillaris. High-quality OCTA images have also enabled the visualization of features ...

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    8. Comparison of retinal vessel diameter measurements from swept-source OCT angiography and adaptive optics ophthalmoscope

      Comparison of retinal vessel diameter measurements from swept-source OCT angiography and adaptive optics ophthalmoscope

      Background/ims To compare the retinal vessel diameter measurements obtained from the swept-source optical coherence tomography angiography (OCTA; Plex Elite 9000, Carl Zeiss Meditec, USA) and adaptive optics ophthalmoscope (AOO; RTX1, Imagine Eyes, France). Methods Fifteen healthy subjects, 67% women, mean age (SD) 30.87 (6.19) years, were imaged using OCTA and AOO by a single experienced operator on the same day. Each eye was scanned using two OCTA protocols (3×3 mm 2 and 9×9 mm 2 ) and two to five AOO scans (1.2×1.2 mm 2 ). The OCTA and AOO scans were scaled to ...

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    9. Quantitative Microvascular Analysis With Wide-Field Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

      Quantitative Microvascular Analysis With Wide-Field Optical Coherence Tomography Angiography in Eyes With Diabetic Retinopathy

      Importance Wide-field optical coherence tomographic angiography (OCTA) may provide insights to peripheral capillary dropout in eyes with diabetic retinopathy (DR). Objective To describe the diagnostic performance of wide-field OCTA with and without large vessel removal for assessment of DR in persons with diabetes. Design, Setting, and Participants This case-control study was performed from April 26, 2018, to April 8, 2019, at a single tertiary eye center in Singapore. Case patients were those with type 2 diabetes for more than 5 years and bilateral DR diagnosed by fundus imaging; control participants included those with no self-reported history of diabetes, a fasting ...

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    10. 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 ...

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    11. Optical coherence tomography angiography for the assessment of choroidal vasculature in high myopia

      Optical coherence tomography angiography for the assessment of choroidal vasculature in high myopia

      Aims To assess specific layers of the choroid in highly myopic young adults and to examine their associations with levels of myopia. Methods We recruited 51 young myopes (n=91 eyes) from the Singapore Cohort of Risk Factors for Myopia cohort. We performed standardised optical coherence tomography (OCT) and OCT angiography imaging and developed a novel segmentation technique assessing choroidal layers’ thickness (overall choroidal thickness (CT), medium-vessel choroidal layer (MVCL) thickness, large-vessel choroidal layer (LVCL)) and vasculature (choroidal vessel density (%), choroidal branch area (CBA, %) and mean choroidal vessel width (MCVW, mm)). Results We found that eyes with extreme myopia (EM ...

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    12. Compensation of retinal nerve fibre layer thickness as assessed using optical coherence tomography based on anatomical confounders

      Compensation of retinal nerve fibre layer thickness as assessed using optical coherence tomography based on anatomical confounders

      Background/Aims To compensate the retinal nerve fibre layer (RNFL) thickness assessed by spectral-domain optical coherence tomography (SD-OCT) for anatomical confounders. Methods The Singapore Epidemiology of Eye Diseases is a population-based study, where 2698 eyes (1076 Chinese, 704 Malays and 918 Indians) with high-quality SD-OCT images from individuals without eye diseases were identified. Optic disc and macular cube scans were registered to determine the distance between fovea and optic disc centres (fovea distance) and their respective angle (fovea angle). Retinal vessels were segmented in the projection images and used to calculate the circumpapillary retinal vessel density profile. Compensated RNFL thickness ...

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    13. Impact of systemic vascular risk factors on the choriocapillaris using optical coherence tomography angiography in patients with systemic hypertension

      Impact of systemic vascular risk factors on the choriocapillaris using optical coherence tomography angiography in patients with systemic hypertension

      We investigated the characteristics of the choriocapillaris flow voids using optical coherence tomography angiography (OCTA) in 85 patients (164 eyes) with hypertension (mean ± SD age, 56 ± 11 years; 45% women; 20% poorly controlled BP; 16% diabetes) who are without ocular diseases and determined possible correlations with systemic vascular risk factors. Data on 24-hour ambulatory blood pressure (BP), serum creatinine, and urine microalbumin/creatinine ratio (MCR) were collected. Estimated glomerular filtration rate (eGFR) was calculated based on CKD-EPI Creatinine Equation. OCTA imaging (6 × 6 mm scans; AngioVue) with quantitative microvascular analysis of the choriocapillaris was performed. Linear regression was used to ...

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    14. 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 ...

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    15. 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 ...

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    16. Quantitative analysis of choriocapillaris in non-human primates using swept-source optical coherence tomography angiography (SS-OCTA)

      Quantitative analysis of choriocapillaris in non-human primates using swept-source optical coherence tomography angiography (SS-OCTA)

      The choriocapillaris is a unique vascular plexus located posterior to the retinal pigment epithelium. In recent years, there is an increasing interest in the examination of the interrelationship between the choriocapillaris and eye diseases. We used several techniques to study choroidal perfusion, including laser Doppler flowmetry, laser speckle flowgraphy, and optical coherence tomography angiography (OCTA), but with the latter no standardized algorithm for quantitative analysis has been provided. We analyzed different algorithms to quantify flow voids in non-human primates that can be easily implemented into clinical research. In-vivo, high-resolution images of the non-human primate choriocapillaris were acquired with a swept-source ...

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    17. Future clinical applicability of optical coherence tomography angiography

      Future clinical applicability of optical coherence tomography angiography

      Optical coherence tomography angiography (OCT‐A) is an emerging technology that allows for the non‐invasive imaging of the ocular microvasculature. Despite the wealth of observations and numerous research studies illustrating the potential clinical uses of OCT‐A, this technique is currently rarely used in routine clinical settings. In this review, technical and clinical aspects of OCT‐A imaging are discussed, and the future clinical potential of OCT‐A is considered. An understanding of the basic principles and limitations of OCT‐A technology will better inform clinicians of its future potential in the diagnosis and management of ocular diseases.

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    18. Association of iris surface features with iris parameters assessed by swept-source optical coherence tomography in Asian eyes

      Association of iris surface features with iris parameters assessed by swept-source optical coherence tomography in Asian eyes

      Background/aims To characterise the association of iris surface features (crypts, furrows and colour) with iris volume and curvature assessed by swept-source optical coherence tomography (SSOCT) in Asian eyes. Methods Iris crypts (by number and size) and furrows (by number and circumferential extent) were graded from iris photographs. Iris colour was measured by a customised algorithm written on MATLAB (MathWorks, Natick, Massachusetts, USA). The iris was imaged by SSOCT (SS-1000, CASIA, Tomey, Nagoya, Japan). The associations of surface features with iris parameters were analysed using a generalised estimating equation. Results A total of 1704 subjects (3297 eyes) were included in ...

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    1-20 of 20
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    1. (16 articles) Singapore Eye Research Institute
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    Association of iris surface features with iris parameters assessed by swept-source optical coherence tomography in Asian eyes Future clinical applicability of optical coherence tomography angiography Quantitative analysis of choriocapillaris in non-human primates using swept-source optical coherence tomography angiography (SS-OCTA) Vessel density and En-face segmentation of optical coherence tomography angiography to analyse corneal vascularisation in an animal model Optical coherence tomography angiography for the anterior segment Impact of systemic vascular risk factors on the choriocapillaris using optical coherence tomography angiography in patients with systemic hypertension Compensation of retinal nerve fibre layer thickness as assessed using optical coherence tomography based on anatomical confounders Optical coherence tomography angiography for the assessment of choroidal vasculature in high myopia Optical Coherence Tomography Angiography Imaging to monitor Anti-VEGF treatment of Corneal Vascularization in a Rabbit Mode Are choriocapillaris flow void features robust to diurnal variations? A swept-source optical coherence tomography angiography (OCTA) study Evaluation of Age-related Skin Changes and Instrument Reliability Using Clinical Probe Measurements and Imaging Modalities HP-OCT™ wins Victorian AEEA award – nominated for Sir William Hudson award