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    1. Principles and Applications of Fourier Optics

      Principles and Applications of Fourier Optics

      `All of optics is Fourier optics!' While this statement may not be literally true, when there is one basic mathematical tool to explain light propagation and image formation, with both coherent and incoherent light, as well as thousands of practical everyday applications of the fundamentals, Fourier optics is worth studying. This book contains summaries of the principles of Fourier optics that have been developed over the past hundred years and of many applications over the past fifty years, especially since the invention of the laser. This book is intended as a series of guideposts to improve our world through the ...

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    2. Design and optimization of a spectrometer for spectral domain optical coherence tomograph

      Design and optimization of a spectrometer for spectral domain optical coherence tomograph

      There are several factors such as the chosen optical source, central wavelength, spectral bandwidth, spectrometer optical components and the detector specifications that affect the overall performance of a spectral domain optical coherence tomography (SD-OCT) imaging system. Among these factors a good design and implementation of the spectrometer is of paramount importance as it directly affects the system resolution, sensitivity fall-off, maximum imaging depth, SNR and in general the system performance. This study demonstrates the design steps and some considerations during the design of a spectrometer. The imaging performance of this design is assessed. The obtained experimental results prove an improvement ...

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    3. Ultra-compact silicon photonic integrated interferometer for swept-source optical coherence tomography

      Ultra-compact silicon photonic integrated interferometer for swept-source optical coherence tomography

      We demonstrate an ultra-compact silicon integrated photonic interferometer for swept-source optical coherence tomography (SS-OCT). The footprint of the integrated interferometer is only 0.75 × 5     mm 2 . The design consists of three 2 × 2 splitters, a 13 cm physical length (50.4 cm optical length) reference arm, and grating couplers. The photonic integrated circuit was used as the interferometer of an SS-OCT system. The sensitivity of the system was measured to be − 62     dB with 115 μW power delivered to the sample. Using the system, we demonstrate cross-sectional OCT imaging of a layered tissue phantom. We also discuss potential improvements ...

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    4. Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography Findings in Choroidal Neurofibromatosis

      Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography Findings in Choroidal Neurofibromatosis

      The authors report multimodal imaging findings, including enhanced depth imaging-optical coherence tomography, in an affected child with choroidal neurofibromatosis. Novel features such as choroidal vessel compression from choroidal nodules related to neurofibromatosis type 1 and an increased subfoveal choroidal thickness are identified. This is the first report to use EDI-OCT to analyze choroidal features in neurofibromatosis type 1.

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    5. Comparing the In Vivo Diagnostic Accuracy of Digital Periapical Radiography with Cone-beam Computed Tomography for the Detection of Vertical Root Fracture

      Comparing the In Vivo Diagnostic Accuracy of Digital Periapical Radiography with Cone-beam Computed Tomography for the Detection of Vertical Root Fracture

      Introduction The purpose of this study was to determine whether there is a difference in the in vivo diagnostic accuracy of digital radiography (DR) and cone-beam computed tomography (CBCT) imaging in the detection of vertical root fracture (VRF). The presence/absence of VRF was confirmed by visual inspection of the extracted root surface and was the reference standard against which both imaging modalities were compared. Methods Twenty-one unsalvageable teeth from 20 patients that had been radiographed and scanned with CBCT imaging were included in the study. The teeth were atraumatically extracted and visually inspected under a microscope to confirm the ...

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    6. Optical coherence tomography-based predictors for creatine kinase-myocardial band elevation after elective percutaneous coronary intervention for in-stent restenosis

      Optical coherence tomography-based predictors for creatine kinase-myocardial band elevation after elective percutaneous coronary intervention for in-stent restenosis

      Objectives : We evaluated whether morphological characteristics of neointimal tissue of in-stent restenosis (ISR) lesions assessed by optical coherence tomography (OCT) affect peri-procedural elevation of creatine kinase-myocardial band (CK-MB). Background : The impact of neointimal characteristics of ISR lesions on peri-procedural myocardial injury has not been sufficiently investigated. Methods : A total of 125 patients with ISR lesions underwent elective percutaneous coronary intervention (PCI) and pre-PCI OCT examination. Measurements of CK-MB were performed upon hospitalization, before PCI, and every 8 hours for 24 hours after PCI. CK-MB elevation was defined as levels above the 99 th percentile of the upper reference limit. Neoatherosclerosis ...

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    7. New Insights on acute expansion and longitudinal elongation of bioresorbable vascular scaffolds In-Vivo and at bench test: A note of caution on reliance to compliance charts and nominal length

      New Insights on acute expansion and longitudinal elongation of bioresorbable vascular scaffolds In-Vivo and at bench test: A note of caution on reliance to compliance charts and nominal length

      Objectives : We performed systematic optical coherence tomography (OCT) analyses after BVS implantation in a “real world” setting aiming at evaluating scaffold expansion and longitudinal integrity. Background : A comprehensive elucidation of bioresorbable vascular scaffolds´ (BVS) acute performance in the “real-world” setting is lacking Methods : Acute BVS expansion compared with compliance chart information and longitudinal integrity were assessed in 29 patients (32 lesions) by OCT. In addition, bench experiments with 4 scaffolds were performed with different combinations of deployment pressures and tube stiffness. Results : Scaffold underexpansion, using compliance chart information as reference, was observed in 97% of OCT cross-sections in vivo; however ...

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    8. Importance of Optical Coherence Tomography Grows

      Importance of Optical Coherence Tomography Grows

      Optical coherence tomography (OCT) has become essential to the practice of ophthalmology, offering superior resolution of the retina and some of the adjacent tissues for diagnosis and treatment of eye diseases. New OCT modalities have now been assimilated into ophthalmic oncology to help track the status of ocular and periocular tumors through retinal symptoms. “ Optical coherence tomography imaging of ocular and periocular tumours ,” a review of newer OCT modalities including anterior segment (AS), ultra-high resolution (UHR), spectral domain (SD) and enhanced depth imaging (EDI), describes the current advantages and limitations of their use. Use of OCT shows mixed results The ...

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      Mentions: Cleveland Clinic
    9. Coherent signal composition and global phase determination in signal multiplexed polarization sensitive optical coherence tomography

      Coherent signal composition and global phase determination in signal multiplexed polarization sensitive optical coherence tomography

      We present an analysis of the structural image information acquired with polarization sensitive optical coherence tomography (PS-OCT). In PS-OCT a total of four channels of data are acquired: two orthogonal polarization state components for each of two incident polarization states by which the sample is interrogated. Up to recently, the structural information of the sample was obtained by incoherent summation of these four channels. The four channels can be represented as a Jones matrix for each data point acquired from a sample. We show that the Signal to Noise ratio of the structural information can be improved by 2.3 ...

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    10. True color scanning laser ophthalmoscopy and optical coherence tomography handheld probe

      True color scanning laser ophthalmoscopy and optical coherence tomography handheld probe

      Scanning laser ophthalmoscopes (SLOs) are able to achieve superior contrast and axial sectioning capability compared to fundus photography. However, SLOs typically use monochromatic illumination and are thus unable to extract color information of the retina. Previous color SLO imaging techniques utilized multiple lasers or narrow band sources for illumination, which allowed for multiple color but not “true color” imaging as done in fundus photography. We describe the first “true color” SLO, handheld color SLO, and combined color SLO integrated with a spectral domain optical coherence tomography (OCT) system. To achieve accurate color imaging, the SLO was calibrated with a color ...

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    11. Scalable multiplexing for parallel imaging with interleaved optical coherence tomography

      Scalable multiplexing for parallel imaging with interleaved optical coherence tomography

      We demonstrate highly parallel imaging with interleaved optical coherence tomography (iOCT) using an in-house-fabricated, air-spaced virtually-imaged phased array (VIPA). The air-spaced VIPA performs spectral encoding of the interferograms from multiple lateral points within a single sweep of the source and allows us to tune and balance several imaging parameters: number of multiplexed points, ranging depth, and sensitivity. In addition to a thorough discussion of the parameters and operating principles of the VIPA, we experimentally demonstrate the effect of different VIPA designs on the multiplexing potential of iOCT. Using a 200-kHz light source, we achieve an effective A-scan rate of 3 ...

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    12. Collaboration aims to reduce, treat vision problems in astronauts

      Collaboration aims to reduce, treat vision problems in astronauts

      To reduce and better treat spaceflight-induced visual impairment, University of Houston (UH) optometrists are collaborating on a NASA study that examines ocular changes seen in a number of astronauts. The research, developed by Heidelberg Engineering, uses Spectralis® Optical Coherence Tomography (OCT), which is a technique for obtaining subsurface images of translucent or opaque materials at a resolution equivalent to a low-power microscope. OCT effectively images reflections from within tissue to provide cross-sectional views. This technology is being used to investigate changes in visual acuity, intraocular pressure, the optic nerve and retinal structures in astronauts exposed to long-duration microgravity aboard the ...

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    13. SJC Issues Decision Concerning Recovery Of Lost Profits Damages In Commercial Litigation

      SJC Issues Decision Concerning Recovery Of Lost Profits Damages In Commercial Litigation

      In a noteworthy recent decision addressing the parameters of damages in commercial litigation, the Massachusetts Supreme Judicial Court (SJC) affirmed an order excluding expert testimony concerning future lost profits damages relating to "yet-to-be conceived future products." In LightLab Imaging, Inc. v. Axsun Technologies, Inc., SJC-11374 (July 28, 2014), the SJC held that the trial court was well within its discretion to exclude an expert economist's testimony in support of a plaintiff's claim for future lost profits based on a "hypothetical new product" and extending more than twenty years beyond the term of the contract at issue. In so ...

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    14. Can optical coherence tomography predict early retinal microvascular pathology in type 1 diabetic adolescents without minimal diabetic retinopathy? A single-centre study

      Can optical coherence tomography predict early retinal microvascular pathology in type 1 diabetic adolescents without minimal diabetic retinopathy? A single-centre study

      Background: Optical coherence tomography (OCT) has been proven useful in measuring retinal thickness and volumes in patients with diabetes. Objective: To test whether OCT is able to identify early retinal changes and its potential correlations with metabolic parameters and other microvascular complications. Patients and methods: Thirty patients with type 1 diabetes without minimal diabetic retinopathy (MDR) (17 males, 13 females, aged 14.3±2.4 years) compared with age-matched healthy volunteers were examined with OCT. Diabetes duration, anthropometric measurements, HbA 1c , other microvascular complications (nephropathy, autonomic and peripheral neuropathy) and total serum cholesterol were determined. Results: No statistically significant differences ...

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    15. Optical coherence tomography should be part of the routine monitoring of patients with multiple sclerosis: Commentary

      Optical coherence tomography should be part of the routine monitoring of patients with multiple sclerosis: Commentary

      There is no doubt that optical coherence tomography (OCT) has been an extremely exciting development for medicine and for multiple sclerosis (MS). The value of OCT as a diagnostic tool has been demonstrated and it has been to shown to identify patients with highly active disease (but magnetic resonance imaging (MRI) does both better). Its possible use as an instrument to measure neurodegeneration over time is perhaps the application most welcome to MS neurologists. Readers are directed to a systematic review of OCT 1 and a discussion of the potential and the problems associated with OCT by Green. 2 An ...

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    16. Optical coherence tomography should be part of the routine monitoring of patients with multiple sclerosis: Yes

      Optical coherence tomography should be part of the routine monitoring of patients with multiple sclerosis: Yes

      Magnetic resonance imaging (MRI) of the brain is the most widely established imaging modality for monitoring multiple sclerosis (MS). Although conventional MRI parameters such as the development of new T2 lesions and/or contrast-enhancing lesions are sensitive to inflammatory disease activity, the association between MRI markers of inflammation and disability progression in MS is modest. 1 Conversely, MRI measures of neurodegeneration, such as whole-brain atrophy, correlate well with disability progression, 2 with neurodegeneration considered the principal pathological substrate underlying disability in MS. MRI segmentation techniques also enable the measurement of brain substructure volumes. Gray matter (GM) atrophy is now recognized ...

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    17. Optical coherence tomography should be part of the routine monitoring of patients with multiple sclerosis: No

      Optical coherence tomography should be part of the routine monitoring of patients with multiple sclerosis: No

      Optical coherence tomography (OCT) is an exciting technique that has been applied to multiple sclerosis (MS) research for around the last 10 years. OCT enables rapid, non-invasive in vivo measurement of retinal nerve fibre layer (RNFL) thickness, reflecting neuroaxonal density within the optic nerve. Early studies applied to post-acute optic neuritis 1 demonstrate neuroaxonal loss. Further research extended the scope of OCT, finding that its measures appeared to be a useful surrogate of generalised brain axonal loss in MS patients; progressive RNFL thinning was evident even in the absence of a history of optic neuritis, 2 and RNFL thickness was ...

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    18. Effects of Sex and Age on the Normal Retinal and Choroidal Structures on Optical Coherence Tomography

      Effects of Sex and Age on the Normal Retinal and Choroidal Structures on Optical Coherence Tomography

      Optical coherence tomography (OCT) has become an essential tool in ophthalmology. Advances in OCT technology have made it possible to measure the thickness of the retina, specific retinal layers, and the choroid. In the present study, the body of the literature documenting the normal retinal and choroidal thickness are reviewed and the effects of sex, age, and axial length on retinal/choroidal thickness are discussed. Macular, retinal layer, and choroidal thickness measured on OCT images in normal eyes showed significant variations by sex and age. Macular retinal thickness was greater in men than in women, especially in the center, inner ...

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    19. University of Arizona Receives NIH Grant for Translational Studies and Clinical Pharmacology of New Drugs for Chemoprevention

      University of Arizona Receives NIH Grant for Translational Studies and Clinical Pharmacology of New Drugs for Chemoprevention

      University of Arizona Receives a 2014 NIH Grant for $294,662 for Translational Studies and Clinical Pharmacology of New Drugs for Chemoprevention. The principal investigator is Steven Stratton The program began in 2014 and ends in 2015 Below is a summary of the proposed work. Project 3 will test and clinically validate mechanisms and pharmacologic strategies explored in Projects 1-2, which target Akt-mTOR, AMPK-mTOR, and Fyn/RSK pathways. Advanced clinical/translational study of skin cancer carcinogenesis, biology, and pathophysiology will help reduce morbidity/ mortality, provide insight into keratinocyte signaling, and provide an easily-accessed human model of full-spectrum carcinogenesis for other ...

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    20. Columbia University Receives NIH Grant for Measures Of Human Receptor and Post Receptor Activity

      Columbia University Receives NIH Grant for Measures Of Human Receptor and Post Receptor Activity

      Columbia University Receives 2014 NIH Grant for $532,143 for Measures Of Human Receptor and Post Receptor Activity. The principal investigator is Donald Hood. The program began in 1991 and ends in 2016. Below is a summary of the proposed work. Our long-term objective has been to develop a set of noninvasive techniques for studying the human retina. By applying novel techniques and current theories of phototransduction to the full-field electroretinogram (ERG), we have successfully developed widely-used noninvasive techniques for studying the global activity of the rod and cone receptors, as well as the rod bipolar cells. These indices of ...

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    21. Dynamic dark-light changes in anterior chamber and iris parameters in angle closure patients with novel automatic algorithm using anterior segment optical coherence tomography (AS-OCT)

      Dynamic dark-light changes in anterior chamber and iris parameters in angle closure patients with novel automatic algorithm using anterior segment optical coherence tomography (AS-OCT)

      Purpose To describe the dynamic dark-light changes in anterior chamber (AC) measurements and iris parameters in angle closure patients compared to normal angle patients using a fully automatic algorithm developed for anterior segment optical coherence tomography (AS-OCT). Methods 10 patients (17 eyes with closed angles) and 8 patients (15 eyes with normal angles) on gonioscopic grading were recruited. We acquired images in both dark and light conditions using Visante OCT. Custom software analyzed the images using the iris rim as the landmark instead of the sclera spur. The parameters analyzed included angle opening distance and angle recess area, at 750 ...

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    22. User-guided segmentation for volumetric retinal optical coherence tomography images

      User-guided segmentation for volumetric retinal optical coherence tomography images

      Despite the existence of automatic segmentation techniques, trained graders still rely on manual segmentation to provide retinal layers and features from clinical optical coherence tomography (OCT) images for accurate measurements. To bridge the gap between this time-consuming need of manual segmentation and currently available automatic segmentation techniques, this paper proposes a user-guided segmentation method to perform the segmentation of retinal layers and features in OCT images. With this method, by interactively navigating three-dimensional (3-D) OCT images, the user first manually defines user-defined (or sketched) lines at regions where the retinal layers appear very irregular for which the automatic segmentation method ...

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    23. Swept source optical coherence tomography artifacts in glaucoma patients

      Swept source optical coherence tomography artifacts in glaucoma patients

      Purpose To demonstrate the frequency and the type of swept-source optical coherence tomography (SS –OCT) imaging artifacts in patients being evaluated glaucoma and to present common artifacts examples Methods The SS–OCT images of 101 glaucoma suspect and glaucoma patients were used to evaluate image artifacts. We used a 3 dimensional imaging data set of 6x6mm raster scan centered on the optic disc (3D disc scan) and a 3 dimensional imaging data set of 12 mm horizontal line scan centered between optic disc and the fovea (3D side scan). For each scan, both printout report and the source image of ...

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    24. Fourier-domain optical coherence tomography evaluation of clear corneal incision structure according to blade material

      Fourier-domain optical coherence tomography evaluation of clear corneal incision structure according to blade material

      Purpose To use Fourier-domain optical coherence tomography (OCT) to evaluate the wound characteristics of clear corneal incisions (CCIs) created with a metal or diamond blade in cataract surgery. Setting Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea. Design Prospective comparative observational study. Methods Patients who had cataract surgery were randomized into 2 groups based on whether a metal blade (Group 1, 37 eyes) or diamond blade (Group 2, 33 eyes) was used to create a 2.8 mm temporal CCI. One day, 1 week, and 1 month postoperatively, structural characteristics of the CCI ...

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