Researcher:
Taş, Ayşe Yıldız

Profile Picture
ORCID

Job Title

Faculty Member

First Name

Ayşe Yıldız

Last Name

Taş

Name

Name Variants

Taş, Ayşe Yıldız

Email Address

Birth Date

Filters

2017 - 201952020 - 202229

Advanced Search

Filter by

Settings

Researcher Of Publications: search.filters.isAuthorOfPublication.0252034c-bda9-4245-acba-d2a88270ce19

Search Results

Now showing 1 - 10 of 34
  • Placeholder
    PublicationMetadata only
    Peripapillary choroidal vasculature in pediatric eyes with type 1 diabetes mellitus
    (Kare Yayıncılık, 2022) N/A; N/A; Hasanreisoğlu, Murat; Kesim, Cem; Uzunay, Nur Sena; Taş, Ayşe Yıldız; Karslıoğlu, Melisa Zişan; Şahin, Afsun; Faculty Member; Teaching Faculty; Undergraduate Student; Faculty Member; Doctor; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; School of Medicine; School of Medicine; School of Medicine; N/A; School of Medicine; N/A; N/A; N/A; N/A; Koç University Hospital; N/A; 182001; 387367; N/A; 200905; N/A; 171267
    Objectives: choroidal vasculature change in children with diabetes mellitus is not investigated enough although it could reflect clinical outcome. Methods: pediatric Type 1 diabetes mellitus (T1DM) patients and healthy controls were retrospectively evaluated. Peripapillary retinal nerve fiber layer optical coherence tomography (OCT) images of the right eyes were analyzed. Choroidal parameters including total choroidal area, luminal area, stromal area, and choroidal vascularity index were measured through image binarization. Results: twenty eyes of 20 patients were compared with 46 eyes of 46 healthy controls. Mean total choroidal area, luminal area, and stromal area were 1.59±0.35, 1.10±0.24, and 0.50±0.13 mm2 in patients’ eyes and 1.52±0.49, 1.05±0.34, and 0.47±0.17 mm2 in healthy eyes. No difference was found in choroidal vascularity indices between patients and healthy eyes (68.8±3.9% vs. 69.4±4.4%, p=0.521). Temporal choroidal vascularity index was significantly higher than its nasal counterpart in healthy eyes (71.8±5.0% vs. 68.6±4.9%, p<0.001) which was not significant in patients’ eyes (70.7±4.0% vs. 68.9±5.1%, p=0.067). Temporal quadrant had the highest choroidal vascularity index score among all quadrants in healthy controls (all p<0.05), whereas no choroidal vascularity index difference between quadrants was detected in patients (p=0.75). Conclusion: peripapillary choroidal vasculature has shown subtle sectoral changes which did not reflect the overall peripapillary OCT section in pediatric T1DM patients when compared with healthy controls.
  • Placeholder
    PublicationMetadata only
    The effect of thyroid eye disease on corneal biomechanical properties
    (Kare Yayıncılık, 2022) N/A; Cömert, Melis Cansu; Yılmaz, Sezen Güçlü; Taş, Ayşe Yıldız; Şahin, Afsun; Undergraduate Student; Undergraduate Student; Faculty Member; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; N/A; N/A; 200905; 171267
    Objectives: the aim of this study was to identify corneal biomechanical parameters measured by ORA in patients with TED compared to the healthy group. The NOSPECS classification of patients is used to assess the relation between biomechanical changes and disease severity. Methods: we included 22 TED patients, diagnosed with TED for more than five years, and 43 healthy participants. The NOSPECS classification was assessed as mild (grade 1-3) and severe (grade 4-6) disease. For each group, corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), Goldmann-correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) parameters were measured by ORA. Results: the mean age was 38.8±11.6 years for the TED patients and 42.9±15.58 years for the control group. For TED patients and healthy volunteers, the mean levels of CRF, CH, and CCT were measured as follows: 10.43±2.04 vs 10.28±1.91mmHg, p=0.67; 10.18±1.81 vs 10.21±1.68 mmHg, p=0.90; 550.31±35.73 vs 545.23±37.91 µm, p=0.47, respectively. These values were not significant between groups, but they were significantly higher in females compared to males in TED patients [CRF;10.68 (IQR: 9.49-12.14) vs 8.96 (IQR: 8.04-9.92) mmHg, p=0.002, CH; 10.43 (IQR: 9.48-11.25) vs 8.58 (IQR: 7.90-9.95) mmHg, p=0.003 and CCT; 554.25 (IQR: 536.05-579.52) vs 527.40 (IQR: 492.25-545.90) μm, p=0.014]. CRF values were negatively correlated with NOSPECS score (r=-0.317, p=0.036) and significantly higher CRF was observed in mild patients compared to severe disease (11.43 (IQR: 10.14-12.87) vs 9.46 (IQR: 8.75-10.28) mmHg, p=0.008). Conclusion: we found a significant gender effect on corneal biomechanical parameters of TED patients. CRF, CH and CCT values were significantly higher in females compared to males with TED. The clinical severity score of TED showed negative correlation with CRF. CRF value might be a useful parameter in follow-up of TED patients in clinical practice.
  • Placeholder
    PublicationMetadata only
    Noninvasive optical coherence tomography imaging correlates with anatomic and physiologic end-organ changes in healthy normotensives with systemic blood pressure variability
    (Lippincott Williams & Wilkins, 2020) Afşar, Barış; Sağ, Alan A.; N/A; Dağel, Tuncay; Derin, Gözde; Kesim, Cem; Taş, Ayşe Yıldız; Şahin, Afsun; Dinçer, Neris; Kanbay, Mehmet; Doctor; Undergraduate Student; Teaching Faculty; Faculty Member; Faculty Member; Undergraduate Student; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; N/A; 387367; 200905; 171267; 349025; 110580
    Objective: Blood pressure variability (BPV) is considered as a novel risk factor for cardiovascular disease including left ventricular hypertrophy, vascular stiffness, and renal dysfunction. In this study, we aimed to determine the relationship between ambulatory BPV with subclinical organ damage and vascular stiffness parameters in normotensive healthy subjects. Methods: A total of 100 healthy subjects over 18 years of age were included in this cross-sectional study. We divided the participants into two groups according to the median value of the SD of mean 24-h blood pressure (BP) (Group 1: SD of mean 24-h BP 10.15). BPs of these subjects were recorded over a 24-h period using ambulatory BP monitoring. Mobil-O-Graph device was used to estimate the augmentation index (AIx), pulse wave velocity (PWV), and ambulatory BP measurement. The choroidal thickness was measured by using optical coherence tomography device. Results: The mean age of the patients was 25.4 +/- 5.0 years. Choroidal thickness was correlated with PWV, AIx, protein excretion, and SD of systolic and diastolic BP (P < 0.05). Additionally, participants with higher BP variability have lower choroidal thickness and higher AIx. Conclusion: We showed that even in normotensive subjects, BPV correlates with choroid thickness. Thus, BPV can be an early prognostic parameter for pathologic vascular changes.
  • Placeholder
    PublicationMetadata only
    Generative adversarial network based automatic segmentation of corneal subbasal nerves on in vivo confocal microscopy images
    (Association for Research in Vision and Ophthalmology, 2021) Arslan, Abdullah Taha; Demir, Sertaç; Barkana, Duygun Erol; Şahin, Afsun; Taş, Ayşe Yıldız; Yıldız, Erdost; Acer, Ali Faik; Faculty Member; Faculty Member; PhD Student; Undergraduate Student; School of Medicine; School of Medicine; Graduate School of Health Sciences; N/A; 171267; 200905; N/A; N/A
    Purpose: In vivo confocal microscopy (IVCM) is a noninvasive, reproducible, and inexpensive diagnostic tool for corneal diseases. However, widespread and effortless image acquisition in IVCM creates serious image analysis workloads on ophthalmol-ogists, and neural networks could solve this problem quickly. We have produced a novel deep learning algorithm based on generative adversarial networks (GANs), and we compare its accuracy for automatic segmentation of subbasal nerves in IVCM images with a fully convolutional neural network (U-Net) based method. Methods: We have collected IVCM images from 85 subjects. U-Net and GAN-based image segmentation methods were trained and tested under the supervision of three clinicians for the segmentation of corneal subbasal nerves. Nerve segmentation results for GAN and U-Net-based methods were compared with the clinicians by using Pearson’s R correlation, Bland-Altman analysis, and receiver operating characteristics (ROC) statis-tics. Additionally, different noises were applied on IVCM images to evaluate the perfor-mances of the algorithms with noises of biomedical imaging. Results: The GAN-based algorithm demonstrated similar correlation and Bland-Altman analysis results with U-Net. The GAN-based method showed significantly higher accuracy compared to U-Net in ROC curves. Additionally, the performance of the U-Net deteriorated significantly with different noises, especially in speckle noise, compared to GAN. Conclusions: This study is the first application of GAN-based algorithms on IVCM images. The GAN-based algorithms demonstrated higher accuracy than U-Net for automatic corneal nerve segmentation in IVCM images, in patient-acquired images and noise applied images. This GAN-based segmentation method can be used as a facilitat-ing diagnostic tool in ophthalmology clinics. Translational Relevance: Generative adversarial networks are emerging deep learning models for medical image processing, which could be important clinical tools for rapid segmentation and analysis of corneal subbasal nerves in IVCM images.
  • Placeholder
    PublicationMetadata only
    Automated diagnosis of keratoconus from corneal topography
    (Assoc Research Vision Ophthalmology Inc, 2021) N/A; N/A; N/A; Department of Industrial Engineering; N/A; Taş, Ayşe Yıldız; Hasanreisoğlu, Murat; Balım, Haldun; Gönen, Mehmet; Şahin, Afsun; Faculty Member; Faculty Member; Master Student; Faculty Member; Faculty Member; Department of Industrial Engineering; School of Medicine; School of Medicine; Graduate School of Sciences and Engineering; College of Engineering; School of Medicine; 200905; 182001; N/A; 237468; 171267
    Purpose: Although visual inspection of corneal topography maps by trained experts can be powerful, this method is inherently subjective. Quantitative classification methods that can detect and classify abnormal topographic patterns would be useful. An automated system was developed to differentiate keratoconus patterns from other conditions using computer-assisted videokeratoscopy. Methods: This system combined a classification tree with a linear discriminant function derived from discriminant analysis of eight indices obtained from TMS-1 videokeratoscope data. One hundred corneas with a variety of diagnoses (keratoconus, normal, keratoplasty, epikeratophakia, excimer laser photorefractive keratectomy, radial keratotomy, contact lens-induced warpage, and others) were used for training, and a validation set of 100 additional corneas was used to evaluate the results. Results: In the training set, all 22 cases of clinically diagnosed keratoconus were detected with three false-positive cases (sensitivity 100%, specificity 96%, and accuracy 97%). With the validation set, 25 out of 28 keratoconus cases were detected with one false-positive case, which was a transplanted cornea (sensitivity 89%, specificity 99%, and accuracy 96%). Conclusions: This system can be used as a screening procedure to distinguish clinical keratoconus from other corneal topographies. This quantitative classification method may also aid in refining the clinical interpretation of topographic maps.
  • Placeholder
    PublicationMetadata only
    Interobserver and intraobserver agreements of the detection of Demodex infestation by in vivo confocal microscopy
    (Kare Yayıncılık, 2022) Mergen, Burak; Bayraktutar, Betül Nurefşan; Çelik, Ekrem; Arıcı, Ceyhun; Taş, Ayşe Yıldız; Yıldız, Erdost; Şahin, Afsun; Faculty Member; PhD Student; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; Graduate School of Health Sciences; School of Medicine; 200905; N/A; 171267
    Objectives: The purpose of the study was to determine interobserver and intraobserver agreement, repeatability, and intrasubject variation of the detection of Demodex infestation in eyelids of blepharitis patients using in vivo confocal microscopy (IVCM). Methods: Eighty-three eyes of 42 blepharitis patients were included in the study. All eyelids were evaluated from temporal to nasal with IVCM using section mode and 10 lashes with their follicles were imagined, and every image with suspicion of Demodex infestation was recorded. Two experienced and two inexperienced ophthalmologists were masked for the diagnosis and interpreted the IVCM images regarding the presence of Demodex infestation with a 3-week interval. Interobserver and intraobserver agreements were calculated with Cohen’s kappa and its variant statistics between and within experienced observers and between inexperienced observers. Results: While average sensitivity for the diagnosis of demodicosis in IVCM images was 83.35% for experienced and 51.35% for inexperienced observers, the average positive predictive value was 88.6% for experienced observers and 91.05% for inexperienced ones. Interobserver agreement between experienced observers was moderate (κ = 0.529) and intraobserver agreements within experienced observers were perfect (κ = 0.918 for observer-1; κ = 0.958 for observer-2). Interobserver agreement between inexperienced observers was poor (κ = 0.162) and intraobserver agreements within inexperienced observers were fair (κ = 0.427 for observer-3; κ = 0.475 for observer-4). Conclusion: The sensitivity, interobserver and intraobserver agreements in IVCM image analysis for the detection of Demodex infestation were highly associated with the clinical experience on IVCM imaging. In the hands of an experienced clinician, IVCM could be reliable for the diagnosis of ocular demodicosis.
  • Placeholder
    PublicationMetadata only
    Validation results of a deep learning algorithm for detection of diabetic retinopathy with lesion localization from retinal fundus photographs
    (Assoc Research Vision Ophthalmology Inc, 2020) Ozkaya, Abdullah; Gokgur, Eren; Cakin, Ilgaz; Yavuz, Utku; Baki, Pinar; Chang, Sung-Yen; N/A; Kesim, Cem; Taş, Ayşe Yıldız; Karslıoğlu, Melisa Zişan; Şahin, Afsun; Doctor; Faculty Member; Doctor; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; School of Medicine; N/A; School of Medicine; Koç University Hospital; N/A; Koç University Hospital; N/A; 387367; 200905; N/A; 171267
    N/A
  • Placeholder
    PublicationMetadata only
    Can rotational thromboelastometry be a new predictive tool for retinal vein occlusion development?
    (Taylor & Francis, 2019) Şahin, Deniz Gören; Özkaya, Abdullah; Bayraktutar, Betül; Taş, Ayşe Yıldız; Akay, Olga Meltem; Yalçın, Özlem; Şahin, Afsun; Doctor; Faculty Member; Faculty Member; Faculty Member; Faculty Member; N/A; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; 200905; 170966; 218440; 171267
    Purpose: To evaluate clotting dynamics by a new tool called rotational tromboelastometry (ROTEM) in retinal vein occlusion.Materials and methods: Thirty-six patients who were diagnosed with retinal vein occlusion and 43 age and sex matched healthy controls were included in this study. Diabetes and use of anticoagulant therapy were exclusion criteria. All study participants underwent detailed ophthalmologic and systemic medical examination, including blood pressure measurement, hemoglobin-hematocrit levels, platelet count, coagulation parameters including prothrombin time, activated partial thromboplastin time, fibrinogen levels, and D-dimer levels. Peripheral blood samples were collected and analyzed with ROTEM Coagulation Analyzer (Tem International, Munich, Germany).Results: The RVO patients and controls did not differ with respect to age, sex, hemoglobin, hematocrit, platelet numbers, prothrombin time, activated partial thromboplastin time, fibrinogen levels, D-dimer levels, and glucose levels. When extrinsic thromboelastometry results were analyzed, RVO patients showed a significantly decreased clotting time (76.515.0 vs. 95.0 +/- 21s, respectively; p =0.01) and clot formation time (83.3 +/- 22 vs. 99.7 +/- 24s; p =0.01) as compared with healthy controls. Other ROTEM parameters did now show any difference between two groups.Conclusion: Patients with retinal vein occlusion showed faster clotting time and shorter clotting formation time as compared with healthy controls. ROTEM detects the altered clotting dynamics and may be a useful tool to elucidate the disease pathophysiology. Further studies are needed to investigate if it can be used as a screening test for individuals who are under risk to develop RVO or as a first step test to evaluate hypercoagulable state in RVO.
  • Placeholder
    PublicationMetadata only
    Investigation of the Demodex lid infestation with in vivo confocal microscopy versus light microscopy in patients with seborrheic blepharitis
    (Taylor & Francis Inc, 2022) Arıcı, Ceyhun; Mergen, Burak; Bahar Tokman, Hrisi; Tokuç, Edip; Öztürk Bakar, Yeşim; Taş, Ayşe Yıldız; Şahin, Afsun; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 200905; 171267
    Aim: The comparison of the diagnostic efficiency of a reference method (light microscopy [LM] using 10% potassium hydroxide [KOH]) with the use of 100% alcohol to in vivo confocal microscopy (IVCM) for the detection of Demodex eyelid infestation in seborrheic blepharitis patients. Methods: Eyelashes were epilated from the right eyes for the reference method and the left eyes for the alcohol group in 58 eyes of 29 patients. IVCM was used on the left eyes. The primary outcomes were the number of Demodex mites per lash and the rate of Demodex positivity (>= 1 mite). Results: The rate of Demodex positivity was similar among the three groups (KOH: 82.8%, alcohol: 86.2%, IVCM: 72.4%; p >.05). The mean number of mites per lash in the KOH group (1.5 +/- 1.3) was higher than in the alcohol (0.9 +/- 0.6, p =.041) and IVCM groups (0.9 +/- 0.9, p =.036). Conclusion: KOH was found to be superior in terms of the quantification of mites compared to alcohol and IVCM.
  • Placeholder
    PublicationMetadata only
    Cataract surgery in patients with corneal disease
    (Medical Network, 2017) N/A; N/A; Müftüoğlu, Orkun; Taş, Ayşe Yıldız; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 188588; 200905
    Preexisting corneal disease can be exacerbated by cataract surgery and may prevent well tolerated cataract extraction. Thisarticle describes how corneal epithelial, stromal, endothelial disease may impact and be impacted by cataract surgery whilehighlighting recommendations for perioperative management and surgical technique. / Kornea problemleri varlığında katarakt cerrahisi, hastanın mevcut bulgularını kötüleştirebilmekte ya da cerrahi basamaklarını zorlaştırabilmektedir. Bu yazının amacı korneal epitelyal, stromal, endotelyal problemlerin katarakt cerrahisinden nasıl etkilendiğini ve katarakt cerrahisi basamaklarını nasıl etkilediğini göz önüne sermektir.