1. Articles in category: Ophthalmology

    577-600 of 6177 « 1 2 ... 22 23 24 25 26 27 28 ... 256 257 258 »
    1. Schematic eye and adjustment method and evaluation method for optical coherence tomography apparatus

      Schematic eye and adjustment method and evaluation method for optical coherence tomography apparatus

      A schematic eye is used for the evaluation of the optical system of an optical coherence tomography apparatus which captures a tomogram of the fundus. The eye includes a first optical member which irradiated light from the optical system strikes and a second optical member which irradiated light from the first optical member strikes. A plurality of layers having different scattering intensities in the incident direction of irradiated light are formed on the second optical member.

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    2. Multi-functional adaptive optics retinal imaging

      Multi-functional adaptive optics retinal imaging

      An optical apparatus includes a system of optical components capable of operating in a scanning laser ophthalmoscope (SLO) mode and an optical coherence tomography (OCT) mode. The system of optical components includes a first optical module for the SLO mode, a second optical module for the OCT mode, and a first scanning device. The first optical module for the SLO mode includes a first source adapted to provide a first imaging beam for the SLO mode and a first detection device configured to receive a first signal associated with a first image of a retina of an eye. The second ...

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    3. Cornea characterization using a combined multiphoton microscopy and optical coherence tomography system

      Cornea characterization using a combined multiphoton microscopy and optical coherence tomography system

      We present a multimodal imaging system which combines multiphoton microscopy and optical coherence tomography to visualize the morphological structures, and to quantify the refractive index (RI) and thickness of cornea. The morphological similarities and differences at different corneal layers across various species are identified. In the piscine and human corneas, the stromata exhibit thin fibers that indicate an overall collagen direction. Human corneas display collagen micro-folds which cause increased light attenuation. In the murine, porcine and bovine corneas, the stromata show interwoven collagen patterns. The Bowman’s layer and the Descemet’s membrane are also distinguished in some species. The ...

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    4. Paracentral acute middle maculopathy spectral-domain optical coherence tomography feature of deep capillary ischemia

      Paracentral acute middle maculopathy spectral-domain optical coherence tomography feature of deep capillary ischemia

      Purpose of Review To describe the novel spectral-domain optical coherence tomography (SD-OCT) finding of paracentral acute middle maculopathy (PAMM) that can be associated with acute macular neuroretinopathy (AMN) or retinal vasculopathy, and that may indicate an underlying pathogenesis related to ischemia of the retinal deep capillary plexus (DCP). Recent Findings With the advent of high-definition SD-OCT imaging, we are now able to detect deep capillary ischemia. Although cotton wool spots are caused by ischemia of the superficial capillary plexus, PAMM is caused by ischemia of the DCP, and appears as hyper-reflective, band-like lesions in the middle retina, extending from the ...

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    5. Optical coherence tomography and visual evoked potentials in healthy persons

      Optical coherence tomography and visual evoked potentials in healthy persons

      Purpose Optical coherence tomography (OCT) and Visual evoked potentials (VEPs) represent non-invasive objective examination of the visual system. While the OCT measures a morphological property of the retina (thickness of the retinal nerve fibre layer – RNFL), the VEP allows assessment a function of the visual system. There are numerous studies describing a mutual involvement of both mentioned aspects in diseases like multiple sclerosis, optic neuritis or glaucoma, however, normative studies of these relationship are missing. In our study we address this issue with an expectation to translate the findings into interpretation of pathological findings. Methods We examined a group of ...

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    6. Structure-Function Correlations in Glaucoma Using Matrix and Standard Automated Perimetry Versus Time Domain and Spectral Domain OCT devices

      Structure-Function Correlations in Glaucoma Using Matrix and Standard Automated Perimetry Versus Time Domain and Spectral Domain OCT devices

      Purpose: To examine the structure-function relationship between two perimetric tests, the Frequency-Doubling Technology (FDT) Matrix and Standard Automated Perimetry (SAP), and two Optical Coherence Tomography (OCT) devices (Time-Domain and Spectral-Domain). Methods: This cross-sectional study included 97 eyes from 29 healthy individuals and 68 individuals with early, moderate, or advanced primary open-angle glaucoma. The correlations between overall and sectorial parameters of retinal nerve fiber layer thickness (RNFL) measured with Stratus and Spectralis OCT and the visual field sensitivity obtained with FDT Matrix and SAP were assessed. The relationship was also evaluated using a previously described linear model. Results: The correlation coefficients ...

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    7. Optic nerve head assesment: comparison of Cirrus optic coherence tomography and Heidelberg Retinal Tomograph 3

      Optic nerve head assesment: comparison of Cirrus optic coherence tomography and Heidelberg Retinal Tomograph 3

      Background The purpose of this study was to analyze the relationship between Optic Nerve Head (ONH) parameters measured by spectral domain optical coherence tomography and confocal scanning laser ophthalmoscope. Design Prospective, cross-sectional study. Hospital setting. Participants One hundred seventy-three subjects (85 glaucoma and 88 normal subjects). Methods One eye from each individual was selected randomly for ONH imaging by the spectral domain Cirrus OCT and Heidelberg Retinal Tomograph 3 (HRT3). Main Outcome Measures Four ONH parameters that are measured by both technologies (average cup to disc ratio (CDR), rim area, disc area and cup volume) were analyzed and compared for ...

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    8. Expanding OCT: Quanitifying the Cornea’s Optical Performance

      Expanding OCT: Quanitifying the Cornea’s Optical Performance

      Optical coherence tomography, a well-known method for imaging the retina, may allow physicians to perform quantitative metrology of the eye’s own optics. Swept-source OCT allows for simultaneous imaging of the cornea, iris and retina in living patients. Laser refractive surgeries such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) have brought better vision to tens of millions worldwide. But these techniques also exact a cost: because they work by reshaping the eye’s cornea, they make accurate measurement of the cornea’s optical parameters after surgery unreliable using conventional tools. That’s important, not only because inaccurate ...

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    9. UC Davis Receives a NIH Grant for studying Structure and Function of The Chorioretinal Complex in Age-Related Macular Degeneration.

      UC Davis Receives a NIH Grant  for studying Structure and Function of The Chorioretinal Complex in Age-Related Macular Degeneration.

      University of California at Davis Receives a 2014 NIH Grant for $563,632 for studying Structure and Function of The Chorioretinal Complex in Age-Related Macular Degeneration. The principal investigator is John Werner. The program began in 2014 and ends in 2019. Below is a summary of the propose work. Three aims are proposed to study the chorioretinal complex (choroid, choriocapillaris, Bruch's membrane, retinal pigment epithelium, photoreceptors) in age-related macular degeneration (AMD). Each aim includes both technical goals involving optical imaging and tests of hypotheses related to the pathogenesis of this disease. Aim 1 will use phase changes between successive ...

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    10. Correlation between Optic Nerve Parameters Obtained Using 3D Nonmydriatic Retinal Camera and Optical Coherence Tomography: Interobserver Agreement on the Disc Damage Likelihood Scale

      Correlation between Optic Nerve Parameters Obtained Using 3D Nonmydriatic Retinal Camera and Optical Coherence Tomography: Interobserver Agreement on the Disc Damage Likelihood Scale

      Purpose . To compare stereometric parameters obtained by three-dimensional (3D) optic disc photography and optical coherence tomography (OCT) and assess interobserver agreement on the disc damage likelihood scale (DDLS). Methods . This retrospective study included 190 eyes from 190 patients classified as normal, glaucoma suspect, or glaucomatous. Residents at different levels of training completed the DDLS for each patient before and after attending a training module. 3D optic disc photography and OCT were performed on each eye, and correlations between the DDLS and various parameters obtained by each device were calculated. Results . We found moderate agreement (weighted kappa value, 0.59 ± 0 ...

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    11. Correlation between Spectral-Domain OCT findings and Visual Acuity in X-linked Retinoschisis

      Correlation between Spectral-Domain OCT findings and Visual Acuity in X-linked Retinoschisis

      PURPOSE: To investigate the tomographic characteristics of the outer retina and choroid and their relationship with visual auity in X-linked juvenile retinoschisis (XLRS) patients using spectral-domain optical coherence tomography (SD-OCT). METHODS: In this retrospective, observational, case-control study, we analyzed 20 eyes of 10 patients with XLRS using SD-OCT. The clinical and tomographic features of the outer retina, including the external limiting membrane (ELM), inner segment/outer segment (IS/OS) junction, cone cell outer segment tips (COST) line, photoreceptor outer segment (PROS) length, and choroid, were evaluated. As controls, 40 age-, sex-, and refraction-matched healthy eyes (1:2 matched) were randomly ...

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    12. Staging Glaucoma Using Stratus OCT in a U.S. Veteran Population

      Staging Glaucoma Using Stratus OCT in a U.S. Veteran Population

      Purpose: This study examines the ability of time domain optical coherence tomography (Stratus OCT) of the retinal nerve fiber layer (RNFL) to discriminate between normal patients and patients with three stages of glaucomatous vision loss in a US veteran population. Methods: A review of consecutive patients who underwent automated perimetry and Stratus OCT Fast RNFL scanning within a 6-month period was conducted. Patients with nonglaucomatous ocular disease that might affect the RNFL or perimetry results were excluded. Glaucomatous eyes were staged using the Hodapp-Parrish-Anderson grading system. Average, quadrant, and individual clock hour RNFL thicknesses and normative results between all groups ...

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    13. Bioptigen Introduces Image-Guided SDOCT Technology to Advance Preclinical Eye Research

      Bioptigen Introduces Image-Guided SDOCT Technology to Advance Preclinical Eye Research

      Bioptigen announced today the availability of EnFace TM color fundus technology delivering image-guided SDOCT into a single, compact, handheld scan head. The new color fundus system provides multiple, integrated modalities into each of Bioptigen’s Envisu TM preclinical SDOCT systems, producing brilliant, color fundus images captured simultaneously with OCT images. The new color image-guided OCT also complements Bioptigen’s volumetric OCT image visualization, and dynamic 3D tissue flattening capabilities to create a powerful, comprehensive suite of tools designed to meet the exacting needs of the ophthalmic research community. Bioptigen's new Envisu SDOCT scan head featuring integrated color fundus camera ...

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    14. Dynamic Changes of Tear Fluid after Cosmetic Transcutaneous Lower Blepharoplasty Measured by Optical Coherence Tomography

      Dynamic Changes of Tear Fluid after Cosmetic Transcutaneous Lower Blepharoplasty Measured by Optical Coherence Tomography

      Purpose To investigate the dynamic changes of tear fluid after cosmetic transcutaneous lower blepharoplasty. Design Prospective, Observational Case Series study. Methods A total of 60 eyes of 30 patients with transcutaneous lower blepharoplasty were involved in the study. All subjects completed the Ocular Surface Disease Index questionnaire and underwent tear film breakup time measurements and the Schirmer test before surgery and 1 week, 1 month, and 3 months after surgery. Tear meniscus parameters measured by optical coherence tomography were recorded. Lower lid margin reflex distance was also measured. At each time point after surgery, these parameters were compared with the ...

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    15. Seeing the Light: How Photonics Continues to Improve Eyesight

      Seeing the Light: How Photonics Continues to Improve Eyesight

      In 1981, Rangaswamy “Sri” Srinivasan, a researcher at IBM’s Thomas J. Watson Research Center, experimented with a pulsed argon fluoride (ArF) excimer laser on turkey leftovers, and lasers have had an ever-growing role in ophthalmology ever since. That landmark resulted in the first laser-based vision-correction techniques, including laser-assisted in situ keratomileusis (lasik) and photorefractive keratectomy (PRK) techniques. Ophthalmology uses numerous photonic technologies – Nd:YAG and femtosecond excimer lasers, 3-D imaging techniques and OCT (optical coherence tomography) – to diagnose and treat eye diseases and vision problems. Today, these techniques are being combined into systems that are revolutionizing the eye surgeon ...

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    16. Differentiation of Compressive from Glaucomatous Optic Neuropathy with Spectral-Domain Optical Coherence Tomography

      Differentiation of Compressive from Glaucomatous Optic Neuropathy with Spectral-Domain Optical Coherence Tomography

      Purpose To compare optic disc topography in eyes with compressive optic neuropathy (CON) and open-angle glaucoma (OAG) using spectral-domain (SD) optical coherence tomography (OCT) and Heidelberg retinal tomograph (HRT) (Heidelberg Engineering GmbH, Heidelberg, Germany). Design Cross-sectional, observational study. Participants A total of 200 eyes from 123 patients with CON (69 eyes) or OAG (58 eyes) and controls (73 eyes). Methods Univariate and multivariate analyses of HRT parameters, SD-OCT circumpapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters. Main Outcome Measures Circumpapillary RNFL, OCT ONH parameters, and HRT parameters. Results The univariate analysis of OCT parameters demonstrated ...

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    17. Completion Of A Study On Retinal Pathology In An Animal Model Of Parkinson’s Disease

      Completion Of A Study On Retinal Pathology In An Animal Model Of Parkinson’s Disease

      Phoenix Research Labs, Inc., Neuropore Therapies, and UC San Diego today announced breakthrough study results from an industry-academia collaborative effort demonstrating the utility and relevance of Phoenix’s retinal imaging technology as a non-invasive and effective method to evaluate and track the progression of neurodegenerative changes in animal models of Parkinson’s disease. This technology provides researchers with a fundamental new tool for detecting and tracking the progression of the underlying neuropathology in these disorders over time in an individual animal. The ability to non-invasively measure the developing neuropathology within the central nervous system provides investigators with a, previously missing ...

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    18. A systematic correlation of morphology and function using spectral domain optical coherence tomography and microperimetry in patients with geographic atrophy

      A systematic correlation of morphology and function using spectral domain optical coherence tomography and microperimetry in patients with geographic atrophy

      Aims This study has been designed to describe the functional impact of distinct pathologies within the retinal layers in patients with geographic atrophy (GA) by means of a point-to-point correlation between optical coherence tomography (OCT) and microperimetry. Methods Retinal morphology and function of 23 patients suffering from GA of the retinal pigment epithelium (RPE) have been investigated using the Spectralis OCT (Heidelberg Engineering) and the MP1 microperimeter (Nidek Technologies). The point-to-point overlay of morphology and function has been done using proprietary software, allowing OCT image grading to define distinct alterations of the neurosensory retina, the RPE and the choroid. By ...

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    19. Structure-function relationships with spectral-domain optical coherence tomography retinal nerve fiber layer and optic nerve head measurements

      Structure-function relationships with spectral-domain optical coherence tomography retinal nerve fiber layer and optic nerve head measurements

      Purpose: To evaluate the regional structure-function relationship between visual field sensitivity and retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) measurements using spectral-domain optical coherence tomography (SD-OCT). Methods: Prospective cross-sectional study conducted on patients with glaucoma, suspected glaucoma and healthy subjects. Eyes were tested on Cirrus OCT and standard achromatic perimetry. RNFL thickness of 12 peripapillary 30° sectors, neuroretinal rim thickness extracted from 36 neuroretinal rim scans, and Bruch membrane opening minimum rim width (BMO-MRW) - a recently defined parameter - extracted from 36 neuroretinal rim scans were obtained. Correlations between peripapillary RNFL thickness, neuroretinal rim thickness, all six ...

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    20. Fluorescein Angiography Versus Optical Coherence Tomography-Guided Planning for Macular Laser Photocoagulation in Diabetic Macular Edema

      Fluorescein Angiography Versus Optical Coherence Tomography-Guided Planning for Macular Laser Photocoagulation in Diabetic Macular Edema

      Purpose: To compare laser photocoagulation plans for diabetic macular edema (DME) using fluorescein angiography (FA) versus optical coherence tomography (OCT) thickness map superimposed on the retina. Methods: Fourteen eyes with DME undergoing navigated laser photocoagulation with navigated photocoagulator had FA taken using the same instrument. Optical coherence tomography central retinal thickness map was imported to the photocoagulator and with same magnification aligned onto the retina. Three retina specialists placed laser spot marks separately on FA and OCT image in a masked fashion. The spots placed by each physician were compared between FA and OCT and among physicians. The area of ...

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    21. Anterior Segment Biometry Using Spectral-Domain Optical Coherence Tomography

      Anterior Segment Biometry Using Spectral-Domain Optical Coherence Tomography

      PURPOSE: To compare the anterior chamber and anterior chamber angle measurements obtained with spectral-domain anterior segment optical coherence tomography (AS-OCT) and time-domain AS-OCT. METHODS: The anterior chamber of healthy participants was imaged with spectral-domain AS-OCT (Casia SS-1000; Tomey, Nagoya, Japan) and time-domain AS-OCT (Visante; Carl Zeiss Meditec, Dublin, CA). Central corneal thickness (CCT), anterior chamber depth (ACD), angle opening distance at 500 and 750 μm (AOD 500 and AOD 750), trabecular iris space area at 500 and 750 μm (TISA 500 and TISA 750), and scleral spur angle were measured. The intraclass correlation coefficients (ICCs) were calculated. The Pearson correlation ...

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    22. Towards simultaneous Talbot bands based optical coherence tomography and scanning laser ophthalmoscopy imaging

      Towards simultaneous Talbot bands based optical coherence tomography and scanning laser ophthalmoscopy imaging

      We report a Talbot bands-based optical coherence tomography (OCT) system capable of producing longitudinal B-scan OCT images and en-face scanning laser ophthalmoscopy (SLO) images of the human retina in-vivo . The OCT channel employs a broadband optical source and a spectrometer. A gap is created between the sample and reference beams while on their way towards the spectrometer’s dispersive element to create Talbot bands. The spatial separation of the two beams facilitates collection by an SLO channel of optical power originating exclusively from the retina, deprived from any contribution from the reference beam. Three different modes of operation are presented ...

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    23. Doppler Optical Coherence Tomography

      Doppler Optical Coherence Tomography

      Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A ...

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    24. Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo

      Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo

      The relationship between scleral birefringence and biometric parameters of human eyes in vivo is investigated. Scleral birefringence near the limbus of 21 healthy human eyes was measured using polarization-sensitive optical coherence tomography. Spherical equivalent refractive error, axial eye length, and intraocular pressure (IOP) were measured in all subjects. IOP and scleral birefringence of human eyes in vivo was found to have statistically significant correlations ( r = −0.63, P = 0.002). The slope of linear regression was −2.4 × 10 −2 deg/μm/mmHg. Neither spherical equivalent refractive error nor axial eye length had significant correlations with scleral birefringence. To evaluate ...

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