Search results for "Coherence tomography"
showing 10 items of 150 documents
Comparison of two artificial tear formulations for dry eye through high‐resolution optical coherence tomography
2011
Purpose: The aim was to determine the efficacy of two artificial eye-drop formulations by analysing the lower tear film meniscus volume through a commercial high-resolution spectral-domain optical coherence tomographer. Methods: Twenty dry eye patients (12 men, eight women, aged 57.5 ± 8.4 years) with refractive errors from -2.50 to +0.75 D (mean -1.34 ± 1.02 D) and cylinders lower than 1.00 D were examined. Tear meniscus volume was measured before, immediately after and 10, 30 and 60 minutes after instillation using the Copernicus high-resolution spectral-domain optical coherence tomographer (Optopol Tech SA, Zawiercie, Poland). Volume was calculated from the local area obtained from tom…
Optical Coherence Tomography Versus Intravascular Ultrasound to Evaluate Coronary Artery Disease and Percutaneous Coronary Intervention
2013
ObjectivesWe compared intravascular ultrasound (IVUS) and 2 different generations of optical coherence tomography (OCT)—time-domain OCT (TD-OCT) and frequency-domain OCT (FD-OCT)—for the assessment of coronary disease and percutaneous coronary intervention (PCI) using stents.BackgroundOCT is a promising light-based intravascular imaging modality with higher resolution than IVUS. However, the paucity of data on OCT image quantification has limited its application in clinical practice.MethodsA total of 227 matched OCT and IVUS pull backs were studied. One hundred FD-OCT and IVUS pull backs in nonstented (n = 56) and stented (n = 44) vessels were compared. Additionally, 127 matched TD-OCT and …
Retinal nerve fibre layer and brain grey substance as early prognostic factors for disability in multiple sclerosis.
2012
We read with interest the article by Bock et al ,1 in which the association between retinal nerve fibre layer (RNFL) and total macular volume (TMV) was analysed by optical coherence tomography (OCT) and contrast sensitivity was measured by functional acuity contrast testing in relapsing-remitting multiple sclerosis (MS) patients. The authors found that the functional contrast vision in MS is influenced by morphological changes in the anterior visual pathway. This work emphasised that contrast sensitivity is reduced in MS, and that RNFL and TMV, as morphological measures of retinal axon loss, are predictors of contrast sensitivity. Ophthalmological examinations were the basis of the Bock et …
Enhanced depth imaging optical coherence tomography of the choroid in idiopathic macular hole: A cross-sectional prospective study.
2010
Purpose To determine the choroidal thickness in the macular area in patients with idiopathic macular hole in one eye and an unaffected fellow eye and in healthy controls. Design Cross-sectional, prospective study. Methods Twenty-two patients with a full-thickness unilateral idiopathic macular hole and 22 age- and sex-matched controls were recruited. Enhanced depth imaging optical coherence tomography images were obtained by using spectral-domain optical coherence tomography. The choroidal thickness was measured in the subfoveal area and 1000 μm and 2000 μm away from the fovea in the nasal and temporal regions. The diameter of the macular hole and the axial length were determined. Results Ch…
Intravitreal Plasmin Without Associated Vitrectomy as a Treatment for Refractory Diabetic Macular Edema
2009
To determine the effectiveness of a low-dose intravitreal injection of autologous plasmin enzyme (APE), without the performance of a vitrectomy, as a treatment for refractory diffuse diabetic macular edema (DDME).Prospective, comparative, interventional case series.Sixteen patients with bilateral DDME who had not responded to prior laser photocoagulation. All patients received an injection in 1 eye, while the other eye served as a control.Intravitreal 0.2 mL APE injection under topical anesthesia. The APE was obtained using a simplified method.Central macular thickness (CMT) at 1 and 6 months, determined by optical coherence tomography (OCT) and best corrected visual acuity (BCVA).All patie…
Chromatic-achromatic perimetry in four clinic cases: Glaucoma and diabetes
2015
Color perimetry has interesting clinical application for the diagnosis and detection of certain eye conditions, due to the variations that certain diseases can cause in chromatic thresholds, both in the red-green (RG) and the blue-yellow (BY) pathways.[1,2,3,4] The separate study of the visual function of both the chromatic and achromatic mechanisms could be more efficient in detecting sensitivity variations, and such variations would not be obscured by the intrusion of other mechanisms. Currently, the supply of conventional perimeters that are capable of performing a chromatic perimetry test is very limited and with reduced options regarding the possibility of choosing the physical charact…
Reliability of manual segmentation of cornea, contact lens and tear film using a high-resolution OCT
2015
In this study, we aimed to evaluate the intra/inter-session and intra/inter-observer variability of manual segmentation of thickness of the pre-lens tear film, contact lens (CL), post-lens tear film, epithelium, bowman’s layer, stroma and the whole cornea and CLs with a flat and a steep fit, using a commercial high-resolution spectral domain optical coherence tomographer (OCT). Two different observers obtained three repeated measures in two separate sessions. A high correlation was found between the values obtained by the two different observers, except for the thinner layers, epithelium, and Bowman’s layer. Inter-observer analysis showed a high consistency in the measurements obtained by b…
Remote optical sensor of blood coagulation, oximetry and dehydration
2014
An optical approach for remote extraction of vibrations has recently been proposed. We demonstrate the method's ability to continuously monitor three biomedical indicators: blood oximetry, blood coagulation and dehydration of the body.
Online measurement of floc size, viscosity, and consistency of cellulose microfibril suspensions with optical coherence tomography
2021
AbstractIn this study, cellulose microfibril (CMF) suspensions were imaged during pipe flow at consistencies of 0.4%, 1.0%, and 1.6% with optical coherence tomography (OCT) to obtain images of the structure and the local velocity of the suspension. The viscosities obtained by combining pressure loss measurement with the OCT velocity data showed typical shear thinning behavior and were in excellent agreement with viscosities obtained with ultrasound velocity profiling. The structural OCT images were used to calculate the radial and the axial floc sizes of the suspension. A fit of power law to the geometrical floc size–shear stress data gave the same power law index for all consistencies, sug…
Characterization of micro-fibrillated cellulose fiber suspension flow using multi scale velocity profile measurements
2017
Rheological properties and boundary layer flow behavior of Micro Fibrillated Cellulose (MFC) suspended in water was studied using a novel velocity profiling rheometric technique. The method is based on measuring stationary velocity profiles of fluid flow in a straight tube simultaneously by Doppler Optical Coherence Tomography (DOCT) and by Ultrasound Velocity Profiling (UVP). The high resolution DOCT provides velocity profiles near the transparent tube wall, while UVP yields corresponding information in the interior parts of the flow. The data from the two instruments is combined into a comprehensive velocity profile including both the thin boundary layer near the wall and the interior par…