1. Articles from Gábor Márk Somfai

    1-20 of 20
    1. The Use of Optical Coherence Tomography for the Detection of Early Diabetic Retinopathy

      The Use of Optical Coherence Tomography for the Detection of Early Diabetic Retinopathy

      Diabetic retinopathy (DR) is one of the leading causes of vision loss globally with a severe burden on all societies due to its high treatment and rehabilitation costs. The early diagnosis of DR may provide preventive steps (including retinal laser therapy and tight carbohydrate, blood pressure, and cholesterol control) that could in turn help to avoid progression of the pathology with the resultant vision loss. Optical coherence tomography (OCT) enables the in vivo structural imaging of the retina, providing both qualitative (structure) and quantitative (thickness) information. In the past decades, extensive OCT research has been done in the field of ...

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    2. Noninvasive, High-Resolution Functional Macular Imaging in Subjects With Retinal Vein Occlusion

      Noninvasive, High-Resolution Functional Macular Imaging in Subjects With Retinal Vein Occlusion

      BACKGROUND AND OBJECTIVES: Several imaging modalities have been developed to characterize ischemia inherent in retinal vascular diseases. This study aims to predict the impact and to better establish the mechanisms of visual deterioration. A high-resolution functional imaging device is used, yielding quantitative data for macular blood flow and capillary network features in healthy eyes and in eyes with central retinal vein occlusion (CRVO) or branch retinal vein occlusion (BRVO). PATIENTS AND METHODS: This prospective, cross-sectional, comparative case series measured blood flow velocities (BFVs) and noninvasive capillary perfusion maps (nCPMs) in macular vessels in patients with BRVO/CRVO and in healthy ...

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    3. Inter-session repeatability of retinal layer thickness in optical coherence tomography

      Inter-session repeatability of retinal layer thickness in optical coherence tomography

      Reliable retinal layer thickness measurements using optical coherence tomography (OCT) are important to track the subtle retinal changes in longitudinal studies. A total of 10 eyes (5 healthy subjects, 40±13 years old) were enrolled to study the inter-session repeatability and identify the pitfalls affecting the reliabilities. Each eye was scanned using spectral domain OCT (Spectralis SDOCT, Heidelberg Engineering) for 3 sessions with 30 seconds rest in between. The first and second sessions were scanned independently and the third one was scanned with the first one as the baseline visit. Each session consisted of a confocal scanning laser ophthalmoscopy (cSLO ...

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    4. Optical Coherence Tomography of the Optic Disc and the Macula in Neurodegenerative Diseases (Book Chapter)

      Optical Coherence Tomography of the Optic Disc and the Macula in Neurodegenerative Diseases (Book Chapter)

      Optical coherence tomography (OCT) was introduced in the beginning of the 1990s as a new imaging tool that enables the high-resolution in vivo examination of biological tissues. It was first used in ophthalmology where the OCT technology revolutionized the diagnostics of the conditions of the macula and the vitreo-retinal interface. Today, there is intensive research on the possible applications of OCT in other specialties, e.g., angiology, oncology, gastroenterology, dermatology, and dentistry. In the future, OCT may play an important role in the diagnosis and monitoring of neurodegenerative diseases, owing to the fact that the retina is such a unique ...

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    5. Performance evaluation of automated segmentation software on optical coherence tomography volume data

      Performance evaluation of automated segmentation software on optical coherence tomography volume data

      Over the past two decades a significant number of OCT segmentation approaches have been proposed in the literature. Each methodology has been conceived for and/or evaluated using specific datasets that do not reflect the complexities of the majority of widely available retinal features observed in clinical settings. In addition, there does not exist an appropriate OCT dataset with ground truth that reflects the realities of everyday retinal features observed in clinical settings. While the need for unbiased performance evaluation of automated segmentation algorithms is obvious, the validation process of segmentation algorithms have been usually performed by comparing with manual ...

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    6. Real-Time Automatic Segmentation of Optical Coherence Tomography Volume Data of the Macular Region

      Real-Time Automatic Segmentation of Optical Coherence Tomography Volume Data of the Macular Region

      Optical coherence tomography (OCT) is a high speed, high resolution and non-invasive imaging modality that enables the capturing of the 3D structure of the retina. The fast and automatic analysis of 3D volume OCT data is crucial taking into account the increased amount of patient-specific 3D imaging data. In this work, we have developed an automatic algorithm, OCTRIMA 3D (OCT Retinal IMage Analysis 3D), that could segment OCT volume data in the macular region fast and accurately. The proposed method is implemented using the shortest-path based graph search, which detects the retinal boundaries by searching the shortest-path between two end ...

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    7. The effect of incorrect scanning distance on boundary detection errors and macular thickness measurements by spectral domain optical coherence tomography: a cross sectional study

      The effect of incorrect scanning distance on boundary detection errors and macular thickness measurements by spectral domain optical coherence tomography: a cross sectional study

      Background To investigate the influence of scan distance on retinal boundary detection errors (RBDEs) and retinal thickness measurements by spectral domain optical coherence tomography (SD-OCT). Methods 10 eyes of healthy subjects, 10 eyes with diabetic macular edema (DME) and 10 eyes with neovascular age-related macular degeneration (AMD) were examined with RTVue SD-OCT. The MM5 protocol was used in two consecutive sessions to scan the macula. For the first session, the device was set 3.5 cm from the eye in order to obtain detectable signal with low fundus image quality (suboptimal setting) while in the second session a distance of ...

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    8. Fractal-based analysis of optical coherence tomography data to quantify retinal tissue damage

      Fractal-based analysis of optical coherence tomography data to quantify retinal tissue damage

      Background The sensitivity of Optical Coherence Tomography (OCT) images to identify retinal tissue morphology characterized by early neural loss from normal healthy eyes is tested by calculating structural information and fractal dimension. OCT data from 74 healthy eyes and 43 eyes with type 1 diabetes mellitus with mild diabetic retinopathy (MDR) on biomicroscopy was analyzed using a custom-built algorithm (OCTRIMA) to measure locally the intraretinal layer thickness. A power spectrum method was used to calculate the fractal dimension in intraretinal regions of interest identified in the images. ANOVA followed by Newman-Keuls post-hoc analyses were used to test for differences between ...

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    9. Spectral domain optical coherence tomography in patients after successful management of postoperative endophthalmitis following cataract surgery by pars plana vitrectomy

      Spectral domain optical coherence tomography in patients after successful management of postoperative endophthalmitis following cataract surgery by pars plana vitrectomy

      Background Acute severe postoperative endophthalmitis may lead to severe vision loss. The aim of this study was the analysis of macular microstructure imaged by spectral domain optical coherence tomography in patients after pars plana vitrectomy due to postcataract endophthalmitis. Methods A cross sectional study was carried out in 17 patients who had cataract surgery in both eyes and underwent unilateral pars plana vitrectomy due to postcataract endophthalmitis. Postoperative best corrected visual acuity was determined in both eyes. Evaluation of macular thickness, macular volume, peripapillary retinal nerve fiber layer thickness and choroidal thickness using enhanced depth imaging technique was performed by ...

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    10. A Morphological Study of Retinal Changes in Unilateral Amblyopia Using Optical Coherence Tomography Image Segmentation

      A Morphological Study of Retinal Changes in Unilateral Amblyopia Using Optical Coherence Tomography Image Segmentation

      Objective The purpose of this study was to evaluate the possible structural changes of the macula in patients with unilateral amblyopia using optical coherence tomography (OCT) image segmentation. Patients and Methods 38 consecutive patients (16 male; mean age 32.4±17.6 years; range 6–67 years) with unilateral amblyopia were involved in this study. OCT examinations were performed with a time-domain OCT device, and a custom-built OCT image analysis software (OCTRIMA) was used for OCT image segmentation. The axial length (AL) was measured by a LenStar LS 900 device. Macular layer thickness, AL and manifest spherical equivalent refraction (MRSE ...

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    11. Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser–assisted and standard cataract surgery

      Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser–assisted and standard cataract surgery

      Purpose: To evaluate and compare thickness changes in the retinal layers in the macula with optical coherence tomography (OCT) segmentation software after femtosecond laser–assisted phacoemulsification (study group) and conventional phacoemulsification (control group).Setting: Department of Ophthalmology, Semmelweis University, Budapest, Hungary.Design: Case-control study.Methods: Total retinal thickness of the macula was evaluated using Stratus OCT 4 to 8 weeks postoperatively. The OCT images were segmented using OCT retinal image analysis software. Regional thickness data in the central area, inner rings, and outer rings were obtained and absolute and relative thicknesses of the individual retinal layers in the 2 study ...

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    12. In Vivo Evaluation of Retinal Neurodegeneration in Patients with Multiple Sclerosis

      In Vivo Evaluation of Retinal Neurodegeneration in Patients with Multiple Sclerosis
      To evaluate macular morphology in the eyes of patients with multiple sclerosis (MS) with or without optic neuritis (ON) in previous history. Optical coherence tomography (OCT) examination was performed in thirty-nine patients with MS and in thirty-three healthy subjects. The raw macular OCT data were processed using OCTRIMA software. The circumpapillary retinal nerve fiber layer (RNFL) thickness and the weighted mean thickness of the total retina and 6 intraretinal layers were obtained for each
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    13. Investigation of changes in thickness and reflectivity from layered retinal structures of healthy and diabetic eyes with optical coherence tomography

      Investigation of changes in thickness and reflectivity from layered retinal structures of healthy and diabetic eyes with optical coherence tomography
      OCT is usually employed for the measurement of retinal thickness. However, coherent reflected light carries more information characterizing the optical properties of tissue. Therefore, optical property changes may provide further information regarding cellular layers and early damage in ocular diseases. We investigated the possibility of OCT in detecting changes in the optical backscattered signal from layered retinal structures. OCT images were obtained from diabetic patients without retinopathy (DM, n = 38 eyes) or mild diabetic retinopathy (MDR, n = 43 eyes) and normal healthy subjects (n = 74 eyes). The thickness and reflectivity of various layered structures were assessed using a custom-built algorithm ...
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    14. The structure and function of the macula in patients with advanced retinitis pigmentosa

      The structure and function of the macula in patients with advanced retinitis pigmentosa
      Purpose: To assess the structure and function of the macula in advanced retinitis pigmentosa (RP). Methods: Twenty-nine eyes of 22 patients with RP were compared against 17 control eyes. Time-domain optical coherence tomography (OCT) data were processed using OCTRIMA as a means of quantifying Stratus OCT images. The thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer and inner plexiform layer complex (GCL+IPL), inner nuclear layer and outer plexiform layer complex (INL+OPL) and the outer nuclear layer (ONL) were measured. Multifocal electroretinography (mfERG) was performed; two groups were formed based on the mfERG findings. Fourteen eyes ...
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    15. Layer extraction in rodent retinal images acquired by optical coherence tomography

      Layer extraction in rodent retinal images acquired by optical coherence tomography
      Abstract  Optical coherence tomography (OCT) is a modern technique that allows for in vivo, fast, high-resolution 3D imaging. OCT can be efficiently used in eye research and diagnostics, when retinal images are processed to extract borders of retinal layers. In this paper, we present two novel algorithms for delineation of three main borders in rodent retinal images. The first, fast algorithm is based on row projections in a sliding window. It provides initial borders for a slower but more precise variational algorithm that iteratively refines the borders. The results obtained by the two algorithms are quantitatively evaluated by comparison to ...
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    16. Comparison of retinal thickness by Fourier-domain optical coherence tomography and OCT retinal image analysis software segmentation analysis derived from Stratus optical coherence tomography images

      Comparison of retinal thickness by Fourier-domain optical coherence tomography and OCT retinal image analysis software segmentation analysis derived from Stratus optical coherence tomography images
      Purpose: To compare thickness measurements between Fourier-domain optical coherence tomography (FD-OCT) and time-domain OCT images analyzed with a custom-built OCT retinal image analysis software (OCTRIMA). Methods: Macular mapping (MM) by StratusOCT and MM5 and MM6 scanning protocols by an RTVue-100 FD-OCT device are performed on 11 subjects with no retinal pathology. Retinal thickness (RT) and the thickness of the ganglion cell complex (GCC) obtained with the MM6 protocol are compared for each early treatment diabetic retinopathy study (ETDRS)-like region with corresponding results obtained with OCTRIMA. RT results are compared by analysis of variance with Dunnett post hoc test, while ...
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    17. Imaging lid-parallel conjunctival folds with OCT and comparing its grading with the slit lamp classification in dry eye patients and normal subjects

      Imaging lid-parallel conjunctival folds with OCT and comparing its grading with the slit lamp classification in dry eye patients and normal subjects
      Purpose: to visualize and describe the morphological appearance of lid-parallel conjunctival folds (LIPCOF) using optical coherence tomography (OCT) and to relate it to dry eye signs and symptoms. Methods: LIPCOF grade, non-invasive tear film break-up time (NIBUT), lipid layer's interference pattern and dry eye symptoms were recorded in 17 normal and 33 dry eye cases. LIPCOF was evaluated with slit lamp and visualized with OCT. Three different algorithms for OCT was developed to grade LIPCOF using either tear meniscus height or the covering tear film on the folds evaluated by OCT. Results: The three OCT methods showed significant correlations ...
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    18. Reliability and reproducibility of macular segmentation using a custom-built optical coherence tomography retinal image analysis software

      We determine the reliability and reproducibility of retinal thickness measurements with a custom-built OCT retinal image analysis software (OCTRIMA). Ten eyes of five healthy subjects undergo repeated standard macular thickness map scan sessions by two experienced examiners using a Stratus OCT device. Automatic/semi automatic thickness quantification of the macula and intraretinal layers is performed using OCTRIMA software. Intraobserver, interobserver, and intervisit repeatability and reproducibility coefficients, and intraclass correlation coefficients (ICCs) per scan are calculated. Intraobserver, interobserver, and intervisit variability combined account for less than 5% of total variability for the total retinal thickness measurements and less than 7% for ...
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    19. Evaluation of potential image acquisition pitfalls during optical coherence tomography and their influence on retinal image segmentation

      The development of improved segmentation algorithms for more consistently accurate detection of retinal boundaries is a potentially useful solution to the limitations of existing optical coherence tomography (OCT) software. We modeled artifacts related to operator errors that may normally occur during OCT imaging and evaluated their influence on segmentation results using a novel segmentation algorithm. These artifacts included: defocusing, depolarization, decentration, and a combination of defocusing and depolarization. Mean relative reflectance and average thickness of the automatically extracted intraretinal layers was then measured. Our results show that defocusing and depolarization errors together have the greatest altering effect on all measurements ...
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    20. Optical Coherence Tomography of the Macula in Congenital Achromatopsia

      Optical Coherence Tomography of the Macula in Congenital Achromatopsia
      purpose. It is known that symptoms of congenital achromatopsia are caused by the lack of functioning cones, but there are very few published data on histologic changes in the retina in these cases. This study was conducted to examine in vivo the anatomic structure of the retina of patients with achromatopsia. methods. Fifteen eyes of eight patients with congenital achromatopsia and 18 eyes of nine control subjects were examined by optical coherence tomography. Radial 6-mm scans were taken of the macula. The thickness of the neuroretina was measured both automatically and manually. Measurements were taken at the foveola and at ...
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    1-20 of 20
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    Optical Coherence Tomography of the Macula in Congenital Achromatopsia Imaging lid-parallel conjunctival folds with OCT and comparing its grading with the slit lamp classification in dry eye patients and normal subjects Comparison of retinal thickness by Fourier-domain optical coherence tomography and OCT retinal image analysis software segmentation analysis derived from Stratus optical coherence tomography images Layer extraction in rodent retinal images acquired by optical coherence tomography The structure and function of the macula in patients with advanced retinitis pigmentosa Investigation of changes in thickness and reflectivity from layered retinal structures of healthy and diabetic eyes with optical coherence tomography In Vivo Evaluation of Retinal Neurodegeneration in Patients with Multiple Sclerosis Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser–assisted and standard cataract surgery PREcise Percutaneous Coronary Intervention for Stent OptimizatION in Treatment of COMPLEX Lesion (PRECISION-COMPLEX) Real-Time Risk Score for Glaucoma Mass Screening by Spectral Domain Optical Coherence Tomography: Development and Validation Macrophages in close proximity to the vitreoretinal interface are potential biomarkers of inflammation during retinal vascular disease Vertical scan imaging of Anterior Segment Optical Coherence Tomography for descemet anchoring caterpillar seta: A case report and review of literature