1. Articles from Valentin Aranha dos Santos

    1-10 of 10

    1. The Association between Tear Film Thickness as Measured with OCT and Symptoms and Signs of Dry Eye Disease: A Pooled Analysis of 6 Clinical Trials

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      The Association between Tear Film Thickness as Measured with OCT and Symptoms and Signs of Dry Eye Disease: A Pooled Analysis of 6 Clinical Trials

      Purpose: To determine the association between tear film thickness (TFT) as measured with ultra-high resolution optical coherence tomography (UHR-OCT) and signs and symptoms of dry eye disease (DED). Methods: A total of 450 eyes from 225 patients with DED from six different randomized clinical trials were included in this pooled analysis. In all subjects, TFT was measured with a custom-built UHR-OCT system. Symptoms of DED were quantified using a standardized Ocular Surface Disease Index (OSD)I questionnaire and clinical signs including tear film break up time (TFBUT) and Schirmer I test were assessed. Associations of the average TFT with OSDI ...

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    2. Deep learning segmentation for optical coherence tomography measurements of the lower tear meniscus

      Explore OSA | OSA Publishing Ophthalmology
      Deep learning segmentation for optical coherence tomography measurements of the lower tear meniscus

      The tear meniscus contains most of the tear fluid and therefore is a good indicator for the state of the tear film. Previously, we used a custom-built optical coherence tomography (OCT) system to study the lower tear meniscus by automatically segmenting the image data with a thresholding-based segmentation algorithm (TBSA). In this report, we investigate whether the results of this image segmentation algorithm are suitable to train a neural network in order to obtain similar or better segmentation results with shorter processing times. Considering the class imbalance problem, we compare two approaches, one directly segmenting the tear meniscus (DSA), the ...

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      Mentions: Duke University Medical University of Vienna Singapore Eye Research Institute

    3. Light-induced changes of the subretinal space of the temporal retina observed via optical coherence tomography

      Explore Nature Publishing Group Ophthalmology
      Light-induced changes of the subretinal space of the temporal retina observed via optical coherence tomography

      Photoreceptor function is impaired in many retinal diseases like age-related macular degeneration. Currently, assessment of the photoreceptor function for the early diagnosis and monitoring of these diseases is either subjective, as in visual field testing, requires contact with the eye, like in electroretinography, or relies on research prototypes with acquisition speeds unattained by conventional imaging systems. We developed an objective, noncontact method to monitor photoreceptor function using a standard optical coherence tomography system. This method can be used with various white light sources for stimulation. The technique was applied in five volunteers and detected a decrease of volume of the ...

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      Mentions: Medical University of Vienna

    4. Characterization of dry eye disease in a mouse model by optical coherence tomography and fluorescein staining

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      Characterization of dry eye disease in a mouse model by optical coherence tomography and fluorescein staining

      A custom-built ultrahigh-resolution optical coherence tomography (UHR-OCT) system and fluorescein staining were employed for investigation of a scopolamine induced dry eye mouse model. Acquired data was used to evaluate common and complementary findings of the two modalities. Central corneal thickness as measured by UHR-OCT increased significantly over the study period of 24 hours, from 89.0 ± 3.57 µm to 92.2 ± 4.07 µm. Both techniques were able to show corneal lesions with a large range of severity. Localized fluorescein staining was detected in 5% and diffuse staining in 45% of cases where no epithelial damage was visible with ...

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      Mentions: Duke University Medical University of Vienna Singapore Eye Research Institute

    5. Automatic assessment of tear film and tear meniscus parameters in healthy subjects using ultrahigh-resolution optical coherence tomography

      Explore OSA | OSA Publishing Ophthalmology
      Automatic assessment of tear film and tear meniscus parameters in healthy subjects using ultrahigh-resolution optical coherence tomography

      Many different parameters exist for the investigation of tear film dynamics. We present a new tear meniscus segmentation algorithm which automatically extracts tear meniscus area (TMA), height (TMH), depth (TMD) and radius (TMR) from UHR-OCT measurements and apply it to a data set including repeated measurements from ten healthy subjects. Mean values and standard deviations are 0.0174 ± 0.007 mm 2 , 0.272 ± 0.069 mm, 0.191 ± 0.049 mm and 0.309 ± 0.123 mm for TMA, TMH, TMD and TMR, respectively. A significant correlation was found between all respective tear meniscus parameter pairs (all p < 0 ...

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      Mentions: Medical University of Vienna Singapore Eye Research Institute Angelika Unterhuber

    6. Ultrahigh‐resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing

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      Ultrahigh‐resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing

      Purpose To employ ultrahigh‐resolution (UHR) optical coherence tomography (OCT) for investigation of the early wound healing process in corneal epithelium. Methods A custom‐built UHR‐OCT system assessed epithelial healing in human keratoconic cornea after epi‐off crosslinking (CXL) procedure and a wound healing model in rabbits with iatrogenic corneal injury. 3D OCT data sets enhanced obtaining epithelial thickness maps and evaluation of reepithelization stage. Accompanying changes in deeper corneal microarchitecture were analysed. Results The mean central corneal thickness in 40 eyes with keratoconus at baseline was 482.7 ± 38.2 μ m, while mean central epithelial thickness (CET) was ...

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      Mentions: Angelika Unterhuber

    7. Ultrahigh-resolution OCT imaging of the human cornea

      Explore OSA | OSA Publishing Ophthalmology
      Ultrahigh-resolution OCT imaging of the human cornea

      We present imaging of corneal pathologies using optical coherence tomography (OCT) with high resolution. To this end, an ultrahigh-resolution spectral domain OCT (UHR-OCT) system based on a broad bandwidth Ti:sapphire laser is employed. With a central wavelength of 800 nm, the imaging device allows to acquire OCT data at the central, paracentral and peripheral cornea as well as the limbal region with 1.2 µm x 20 µm (axial x lateral) resolution at a rate of 140 000 A-scans/s. Structures of the anterior segment of the eye, not accessible with commercial OCT systems, are visualized. These include corneal ...

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      Mentions: Medical University of Vienna Singapore Eye Research Institute

    8. Effect of different lubricant eye gels on tear film thickness as measured with ultrahigh-resolution optical coherence tomography

      Explore Wiley Online Library Ophthalmology
      Effect of different lubricant eye gels on tear film thickness as measured with ultrahigh-resolution optical coherence tomography

      Purpose To compare the effect of a single drop of different lubricant eye gels on tear film thickness (TFT) as measured with ultrahigh-resolution optical coherence tomography (UHR-OCT) in patients with mild-to-moderate dry eye disease (DED). Methods The study followed a randomized, single-masked, observer-blinded parallel group design. Patients received a single dose of either unpreserved trehalose 3% + hyaluronic acid 0.15% (TH), hyaluronic acid 0.2% (HA) or polyethylene glycol 0.4% + propylene glycol 0.3% (PP) eye drops. In total, 60 patients were included and TFT was measured using a custom-built UHR-OCT system. Results The mean TFT at baseline was ...

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    9. In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography

      Explore OSA | OSA Publishing Ophthalmology
      In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography

      Dry eye syndrome is a highly prevalent disease of the ocular surface characterized by an instability of the tear film. Traditional methods used for the evaluation of tear film stability are invasive or show limited repeatability. Here we propose a new non-invasive fully automated approach to measure tear film thickness based on spectral domain optical coherence tomography and on an efficient delay estimator. Silicon wafer phantom were used to validate the thickness measurement. The technique was applied in vivo in healthy subjects. Series of tear film thickness maps were generated, allowing for the visualization of tear film dynamics. Our results ...

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      Mentions: Medical University of Vienna Angelika Unterhuber

    10. Effect of hyaluronic acid on tear film thickness as assessed with ultra-high resolution optical coherence tomography

      Explore Wiley Online Library Ophthalmology
      Effect of hyaluronic acid on tear film thickness as assessed with ultra-high resolution optical coherence tomography

      Purpose The aim of this study was to assess the effect of a single drop of hyaluronic acid on tear film thickness (TFT) in healthy subjects. Methods Sixteen healthy subjects (eight male/eight female) aged between 20 and 36 years were included in this randomized, double-masked placebo-controlled study. One eye received a single dose of hyaluronic acid (Olixia pure ® ; Croma Pharma, Korneuburg, Austria) eye drops, and the fellow eye received physiologic saline solution as placebo control. The study eye was chosen randomly. TFT as measured with a custom-built Fourier-domain optical coherence tomography (FD-OCT) system was the main outcome variable and ...

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      Mentions: Medical University of Vienna Angelika Unterhuber
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    1. (7 articles) Medical University of Vienna
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    Effect of hyaluronic acid on tear film thickness as assessed with ultra-high resolution optical coherence tomography In vivo tear film thickness measurement and tear film dynamics visualization using spectral domain optical coherence tomography Effect of different lubricant eye gels on tear film thickness as measured with ultrahigh-resolution optical coherence tomography Ultrahigh-resolution OCT imaging of the human cornea Ultrahigh‐resolution anterior segment optical coherence tomography for analysis of corneal microarchitecture during wound healing Automatic assessment of tear film and tear meniscus parameters in healthy subjects using ultrahigh-resolution optical coherence tomography Characterization of dry eye disease in a mouse model by optical coherence tomography and fluorescein staining Light-induced changes of the subretinal space of the temporal retina observed via optical coherence tomography Deep learning segmentation for optical coherence tomography measurements of the lower tear meniscus The Association between Tear Film Thickness as Measured with OCT and Symptoms and Signs of Dry Eye Disease: A Pooled Analysis of 6 Clinical Trials Impact of cardiometabolic factors on retinal vasculature: A 3x3, 6x6 and 8x8-mm optical coherence tomography angiography study Quantitative research on the interaction between cerebral edema and peripheral cerebral blood perfusion using swept-source optical coherence tomography