News

New paper accepted by Investigative Ophthalmology & Visual Science

Our paper, titled 'Predictions of Optic Nerve Traction Forces and Peripapillary Tissue Stresses Following Horizontal Eye Movements', is accepted for publication in Investigative Ophthalmology & Visual Science.

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New paper accepted by Translational Vision Science & Technology

Our paper, titled ' A Digital Staining Algorithm for Optical Coherence Tomography Images of the Optic Nerve Head.', is accepted for publication in Translational Vision Science & Technology.

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Our start-up company Abyss Processing is featured in Asia Pacific Biotech News

Our start-up company Abyss Processing is featured in Asia Pacific Biotech News.

New paper accepted by Biomechanics and Modeling in Mechanobiology

Our paper, titled 'Verification of A Virtual Fields Method to Extract the Mechanical Properties of Human Optic Nerve Head Tissues In Vivo', is accepted for publication in Biomechanics and Modeling in Mechanobiology. recently.

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New paper accepted by IOVS

Our paper, titled 'In Vivo 3-Dimensional Strain Mapping Confirms Large Optic Nerve Head Deformations Following Horizontal Eye Movements', is accepted for publication in IOVS recently.

This study confirms that horizontal eye movements generate significant optic nerve head strains (deformations), which is consistent with our previous estimations using finite element analysis.

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New paper accepted by IOVS

Our paper, titled 'Factors influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations', is accepted for publication in IOVS recently.

This study is the first to study the microcapillary hemodynamics and oxygen concentrations in the optic nerve head using numerical simulations.

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OEIL Research Highlighted at 2016 ARVO Annual Meeting

Last month, four members of our lab attended the ARVO (Association for Research in Vision and Ophthalmology) annual meeting in Seattle, Washington, United States, 1-5 May 2016.

Two of our abstracts were featured as “Hot Topic” during the annual ARVO meeting.This distinction, awarded to just over 2% of all 2016 Annual Meeting abstracts, recognises research that may be indicative of an emerging direction or trend.

- Girard MJA, Birgersson E, Leo HL, Thiery A, Chuangsuwanich T. Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations.
- Wang X, Baskaran M, Rumpel H, Perera S, Lim W, Nongpiur ME, Aung T, Milea D, Girard MJA. Finite element analysis predicts high optic nerve head strains during horizontal eye movements.

Dr Xiaofei Wang received the ARVO Travel Grant to support his travel to the conference.

Our lab head Dr Michael Girard gave his platform presentation on 4 May in Glaucoma Biomechanics session.

Dr Xiaofei Wang, Postdoctoral Research Fellow, gave his platform presentation on 2 May in New Ideas session of glaucoma.

Liang Zhang, PhD candidate, presented his poster :” A Novel Virtual Fields Method to Measure the Biomechanical Properties of Human Optic Nerve Head Tissues“ on 2 May.

New paper accepted by Ophthalmology (IF: 6.1)

Our group has published the first in vivo optic nerve head biomechanics paper in the leading journal Ophthalmology (IF: 6.1).

In our study, we found associations between strain and visual field loss, reinforcing the notion that biomechanics may play an important role in the pathogenesis of glaucoma. More info can be found here.

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New paper accepted by IOVS

Our paper, titled 'Finite Element Analysis Predicts Large Optic Nerve Head Strains During Horizontal Eye Movements', is accepted for publication in IOVS recently.

This study is the first to combine finite element analysis with MRI to estimate optic nerve head strains during eye movements. Our models predict high ONH strains during eye movements, which were aggravated with stiffer optic nerve sheaths.

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New paper accepted by Ophthalmology (IF: 6.1)

Our group has published the first in vivo optic nerve head biomechanics paper in the leading journal Ophthalmology (IF: 6.1).

In our study, we found associations between strain and visual field loss, reinforcing the notion that biomechanics may play an important role in the pathogenesis of glaucoma. More info can be found here.

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New paper accepted by IOVS

Our paper, titled 'Use and Misuse of Laplace's Law in Ophthalmology', is accepted for publication in IOVS recently. In the perspective paper, we reviewed Laplace's Law and questioned its appropriateness for computing wall stress in the eye. We used numerical modelling and studied how Laplace's Law cannot account for important characteristics of the eye, such as variations in globe shape and size or tissue thickness, anisotropy, viscoelasticity or that the eye is a living, dynamic organ. We showed that accounting for various geometrical and material factors, excluded from Laplace’s Law, can alter estimates of corneoscleral wall stress as much as 456%. We concluded by illustrating how computational techniques, such as finite element modeling, can account for the factors mentioned above, and are thus more suitable tools to provide quantitative characterization of corneoscleral biomechanics.

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Dr Girard was interviewed by EyeWorld at the 2015 APACRS Meeting in Kuala Lumpur

Dr. Michael Girard discussed the relationship between corneal biomechanics and glaucoma pathophysiology in an interview by EyeWorld.

See more at EyeWorld

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Our lab's research was featured on Ophthalmology Times

Our lab's research was featured on Ophthalmology Times.

Congratulations to Royston Tan on winning three awards from NUS!

Royston won the High Achivement Award and Merit Achivement Award of 29th Faculty Innovation & Research Awards of NUS Faculty of Engineering for two research projects: 1) Development of a Novel Pupil Expander; 2) Development of Novel Glaucoma Drainage Devices.

He also received the Outstanding Undergraduate Researcher Prize 2014/2015 from the National University of Singapore.

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Meghna and William will present their works in WACBE 2015, Singapore (6 to 8 July, 2015)

Meghna and William will present their works in the coming 7th WACBE World Congress on Bioengineering held in University Town, National University of Singapore, Singapore.

Meghna will present her project on the "In-vivo 3D strain mapping of optic nerve head tissues in humans" in a Biomedical Imaging session (6 July 2015, 5:00pm - 6:30pm, Seminar Room 12).

William will speak about his work on "High-resolution Quantitative Mapping of Microstructural Organisation in Porcine Peripapillary Sclera and Lamina Cribrosa" in another Biomedical Imaging session (7 July 2015, 11:30am - 1:00pm, Seminar Room 12). Click here for the abstracts.

New paper accepted by IOVS

Our group recently published a paper in the reputed eye journal, IOVS. The paper introduces a new shape parameter to characterize the anterior lamina cribrosa surface. The lamina cribrosa is an optic nerve head structure whose morphology is believed to play a role in glaucoma progression. In the paper, we describe the methodology to compute this new parameter and also identify ocular factors associated with it in a group of healthy Indian subjects. We find that a typical healthy lamina has a saddle-rut shape (as depicted in the picture) and that the determinants of lamina shape include risk factors for glaucoma such as axial length, cup-to-disc ratio and minimum rim width.

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We welcome Research Assistant Royston Tan

Royston received his BEng in Biomedical Engineering from NUS in 2015. He is currently working on projects involving medical devices in the field of ophthalmology, collaborating with clinicians from SERI and NUHS to develop them. His work involves design and fabrication of devices, validating them with experimental, theoretical and computational data.

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New paper accepted by IOVS

Recently, our group published a paper in IOVS , titled "Collagen Microstructural Factors Influencing Optic Nerve Head Biomechanics". In this study, we used SALS (Small Angle Light Scattering) to scan cryosectioned human ONH (optic nerve head) tissues and quantified the collagen distribution in the LC (lamina cribrosa) and peripapillary sclera using constrained Von mises distribution. Results showed the collagen fibers in the LC were mostly radially aligned, consistent with SHG (Second Harmonic Generation) images. We also observed a strong circumferential fiber ring, located near but a distance away from the scleral canal boundary. 2D finite element models were constructed using nonlinear, anisotropic, heterogeneous hyper-elastic constitutive equations, incorporating the fiber distribution information from the SALS experiments. The simulations and following sensitivity analysis showed that the strong fiber ring in the peripapillary sclera reduced the strain level near the scleral canal, created a low strain ring. This indicated that collagen fiber ring might act as a self-protection mechanism for the eye.

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We welcome PhD Student Thanadet Chuangsuwanich and Postdoctoral Fellow Dr Xiaofei Wang

Thanadet is currently a NUS PhD Research Scholar. He received his BEng in Biomedical Engineering from NUS (2014). He will focus his research on lamina cribrosa blood flow and oxygen diffusion.

Dr Xiaofei Wang is a Postdoctoral Research Fellow and obtained his PhD in 2014 from the University of New South Wales, Australia. Xiaofei previously worked on the biomechanical of optic chiasmal compression. He will focus his research on optic nerve head and optic nerve biomechanics using finite element, MRI/OCT imaging, and image processing.

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We welcome PhD Students Yu Quan, and David Tan

Yu Quan received his BEng in Engineering Science Program and a second degree in Mathematics from NUS (2010-2014). Yu Quan is currently a PhD candidate and aims to develop techniques to characterise iris biomechanics in vivo.

David Tan received his BEng from the Department of Biomedical Engineering at NUS (2010-2014). David is currently a PhD candidate and aims to develop techniques to characterise corneal and anterior scleral biomechanics in vivo.

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We welcome Research Assistant Sri Gowtham Thakku

Gowtham is a Research Assistant jointly appointed by the Singapore Eye Research Institute (SERI) and the Department of Biomedical Engineering, National University of Singapore (NUS).

He graduated with a degree in Mechanical Engineering from NUS (2013) and is currently working on two projects, both aimed at identifying biomarkers for glaucoma, but each looking at a different region within the eye. By applying image processing techniques, he is attempting to characterize features of the iris and lamina cribrosa, two structures whose morphologies are hypothesized to correlate with glaucoma. Successful identification of such morphologic characteristics holds potential for early glaucoma screening and diagnosis.

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New paper on ocular biomechanics accepted in Interface (IF: 4.907)

A new review paper entitled "In vivo Optic Nerve Head Biomechanics: Performance Testing of a 3D tracking algorithm" has been accepted in the Journal of the Royal Society Interface. This paper represents a steping stone for future biomechanical characterization of the optic nerve head tissues in vivo. We are currently using such methodology to establish a link between measures of biomechanics and vision loss progression in both cross-sectional and longitudinal studies.

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We have released Reflectivity 3.2

Reflectivity 3.2 can significantly improve OCT image quality. It now incorporates our new adaptive compensensation algorithm to limit noise amplification in the deepest tissue layer, thus providing better visibility. Reflectivity 3.2 can also process images captured with intravascular OCT.

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We welcome PhD students Meghna Beotra and Zhang Liang

Zhang Liang is currently a NGS (NUS Graduate School for Integrative Science and Engineering) scholar. He received his BEng in Engineering Science Program from NUS in July 2013.

Meghna is currently a NUS Research Scholar. She received her B.E. in Biomedical Engineering from Manipal Institute of Technology, Manipal University, India (2009-2013).

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We welcome William Chung who just recently joined the lab

William is a Research Associate in the Department of Bioengineering at the National University of Singapore (NUS). William received his BEng in Mechanical Engineering and MSc in Bioinformatics from NUS. He was awarded with the NUS research scholarship and have pursued his PhD study since 2007.

Throughout his career, William has acquired knowledge and experience in bioinformatics, experimental work, and computational modelling. He has developed algorithms to discover biological pathways, and has built devices and mathematical models to investigate the mechanical properties of soft tissues. He looks forward to apply his skills and expertise in his current research work in corneal biomechanics.

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New lamina cribrosa review paper accepted in Current Eye Research

A new review paper entitled "Imaging of the Lamina Cribrosa - Perspectives of Pathogenesis and CLinical Applications" has been accepted in Current Eye Research. This paper summarizes a Special Interest Group session conducted during the 2012 Association of Research in Vision and Ophthalmology meeting to discuss the current status and future directions of optical coherence tomography imaging of the lamina cribrosa.

The photograph above was captured during this Special Interest Group. Panelist members from left to right: Larry Kagemann, Nicholas Strouthidis, Michael Girard, Tae-Woo Kim, Christopher Leung, Kyung Rim Sung.

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New paper on adaptive compensation accepted in IOVS (IF: 3.597)

Purpose. To improve the visibility of the lamina cribrosa (LC), including its posterior boundary, in optical coherence tomography (OCT) images of the human optic nerve head (ONH). Methods. An adaptive compensation algorithm was developed to overcome a limitation of our standard compensation algorithm, that is the over-amplification of noise at high depth. Such limitation currently hampers our ability to distinguish the posterior LC boundary. In adaptive compensation, standard compensation operations are performed until an energy threshold is reached, at which stage the compensation process is stopped to limit noise over-amplification in the deeper portion of the OCT image. The performance of adaptive compensation was compared to that of standard compensation using OCT images of 5 human ONHs. Results. Adaptive compensation significantly reduced the intra-layer contrast (a measure of pixel intensity uniformity) in the deeper portion of the OCT images (from 0.62±0.11 to 0.30±0.03; p < 0.001), indicating successful removal of noise over-amplification. Furthermore, adaptive compensation significantly increased the inter-layer contrast (a measure of boundary visibility) across the posterior LC boundary (from 0.29±0.13 to 0.61±0.21; p < 0.001), indicating improved posterior LC boundary visibility. Conclusion. Adaptive compensation provided significant improvement compared to standard compensation by eliminating noise over-amplification at high depth and improving the visibility of the posterior LC boundary. These improvements were performed while maintaining all other benefits of compensation such as shadow removal and contrast enhancement. Adaptive compensation will further help our efforts to characterize in vivo ONH biomechanics for the diagnosis and monitoring of glaucoma.

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We welcome Khai Sing Chin who just recently joined the lab

Ms Chin is currently a Research Engineer in the Department of Bioengineering at the National University of Singapore. She received a B.Eng in Bioengineering from NTU (2005-2009) and a MPhil in Computing from the University of Dundee, UK (2010-2012). Ms Chin's research interests include Biomedical Engineering and Medical Image Processing.

Ms Chin is currently helping develop techniques to perform compensation, automated segmentation, and 3D deformation tracking of the optic nerve head tissues from optical coherence tomography images.

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We have released Reflectivity 2.0

Reflectivity 2.0 will let you compensate OCT and Ultrasound image data not only in the .vol format (from Heidelberg Engineering) but now also in .png, .jpg, .gif, .bmp, and .tif formats. Two control parameters (Factor In: de-compression operation, Factor Out: re-compression operation) can be used to optimize the compensation. We recommend that you start with the default values provided. In brief, compensation can now be applied to data gathered with other OCT devices (Cirrus, Bioptigen, etc) or Ultrasound devices.

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Our Constitutive Model for the Sclera was Implemented in FEBio

FEBio users can now use a constitutive model to simulate the biomechanical behavior of the sclera (the white outer shell of the eye). This is a constitutive model based on fiber-reinforced composite theory. Collagen fibers are multi-directional: they are distributed within the plane tangent to the tissue surface and they follow a unimodal distribution. Two von-Mises distributions can be used: the standard semi-circular von-Mises distribution and a von-Mises mixture (constrained) that was found to describe with high fidelity collagen fiber orientation in scleral tissues (based on small angle light scattering measurements). FEbio is a nonlinear finite element solver that is specifically designed for biomechanical applications. Febio can be downloaded at this link.

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New Biomechanics of the Eye Meeting in Genoa, Italy (22-24 July 2013)

Dear Colleague, several physiological and pathological processes in the eye are closely related to fluid and/or solid mechanics, and for this reason the biomechanics community has devoted increasing attention to this area in recent years. If research in this area is to have clinical impact, it must be performed within a multidisciplinary framework, and this Colloquium is designed to bring together researchers with complementary expertise from different backgrounds, including clinicians, basic scientists, engineers and mathematical modellers. The topics of the Colloquium are any aspect of the physiology or pathology of the eye in which mechanics plays a role, including for example the following:

  • Tear film dynamics
  • Mechanics of the cornea, sclera, iris and lens
  • Aqueous humour motion and drainage
  • Vitreous humour dynamics
  • Retinal detachment
  • Mechanics of glaucoma
  • Eye movements

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New Article in Current Opinion in Pharmacology (IF: 6.856)

Over the past decade, engineering principles have been used to explain why a mechanical load, intraocular pressure, can lead to the development of glaucomatous optic neuropathy. This has led to the ‘biomechanical theory’ of glaucoma, which posits that the behavior of optic nerve head connective tissues (specifically within the peripapillary sclera and lamina cribrosa) in response to intraocular pressure (regardless of its magnitude) can directly and indirectly influence the physiology and pathophysiology of the optic nerve head. Given that the biomechanics of the sclera and lamina cribrosa probably influence retinal ganglion cell loss in glaucoma, the idea that altering biomechanical behavior might be protective against glaucoma is an appealing notion. There is some evidence to suggest that stiffening the peripapillary sclera may be protective against the development of glaucoma in an animal model. It is technically possible to stiffen the sclera in vivo using collagen cross-linking techniques already applied in vivo to the cornea in the treatment of keratoconus. It has yet to be established whether scleral cross-linking is safe in humans and that it confers anything more than a theoretical advantage in terms of reducing the risk of glaucomatous damage.

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Our article is currently being featured in OCT news

Optical Coherence Tomography (OCT) has recently emerged as a promising technology for intravascular guidance of interventions. With a resolution on the order of 10 microns, Intravascular OCT surpasses Intravascular Ultrasounds, and allows for precise measurement of cap thickness and identification of lipid rich Thin-Cap Fibroatheroma (TCFA). The diagnostic accuracy and assessment of atherosclerotic plaque morphology with OCT remains however limited by the rapid attenuation of OCT signal in tissue, limiting contrast on deep plaque structure and accurate assessment of plaque burden.

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