Researcher:
Kesim, Cem

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Doctor

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Cem

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Kesim

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Kesim, Cem

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2020 - 202332

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    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.
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    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.
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    Visual acuity, defocus curve and patient satisfaction of a new hybrid EDOF-multifocal diffractive intraocular lens
    (Sage Publications Ltd, 2022) Özturkmen, Cem; Karadeniz, Pınar Günel; N/A; Kesim, Cem; Şahin, Afsun; Doctor; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; School of Medicine; 387367; 171267
    Purpose: To evaluate the visual acuity, defocus curve and visual quality of life following bilateral implantation of a new hybrid extended depth of focus (EDOF)-multifocal diffractive intraocular lens (IOL). Methods: Patients who underwent cataract surgery with bilateral implantation of Tecnis Synergy IOL were enrolled in this study. The main outcomes were defined as uncorrected distant, intermediate and near visual acuities (UDVA, UIVA and UNVA, respectively), defocus curve and VF-14 questionnaire aimed for visual performance. Results: The mean +/- SD values for binocular UDVA, UIVA and UNVA were -0.01 +/- 0.04, 0.05 +/- 0.03 and 0.03 +/- 0.05 logMAR, respectively. Defocus curve showed a continuous vision above 0.16 logMAR between +0.50 D and -2.50 D. Patients had good visual performance with mean VF-14 scores above 3 points. Driving at night (3.47 +/- 0.64) was found to be the most difficult task to perform. Spectacle independence was 100% for both distant and near vision. Conclusion: Bilateral implantation of Tecnis Synergy IOL in cataract patients shows good visual acuity and performance, covering a good visual range without any need of spectacles.
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    Astigmatic vectorial analysis in pediatric keratoconus after unilateral cross-linking treatment
    (Lippincott Williams & Wilkins, 2022) Öztürkmen, Cem; N/A; N/A; Kesim, Cem; Şahin, Afsun; Doctor; Faculty Member; School of Medicine; School of Medicine; 387367; 171267
    Purpose: The aims of this study were to evaluate the treatment response of pediatric keratoconus (KC) patients to unilateral corneal collagen cross-linking (CXL) in treated eyes, disease progression in untreated eyes, and define the predictive value of astigmatic parameters by astigmatic vectorial analysis. Methods: Pediatric patients with KC with CXL-treated progressive eye and untreated fellow eye were included. Patients with other ocular conditions and a history of previous ocular surgery were excluded. Astigmatic changes in anterior and posterior corneal surfaces were evaluated with vectorial analysis. The receiver operating characteristic curves were analyzed to detect the best parameter that discriminates treated and untreated groups. Results: Thirty-two eyes of 16 patients with at least 2-year follow-up were analyzed. The maximum keratometry (K) in CXL-treated eyes remained stable (from 53.51 +/- 2.86-53.41 +/- 2.84 diopter (D), P = 0.84) while the steepest K increased in untreated eyes (from 47.82 +/- 1.71-49.59 +/- 3.32 D, P = 0.03). The oblique components of corneal astigmatism in CXL-treated eyes were higher than those of fellow eyes (all P < 0.05), which significantly decreased in the anterior 3-mm zone after treatment (P = 0.048). The mean differential astigmatism magnitudes were significantly higher in treated eyes (all P < 0.05). The refractive centroid remained unchanged in treated eyes (P = 0.553) and shifted in the oblique direction in untreated eyes (P = 0.04). The oblique differential astigmatism in the anterior 7-mm zone showed the highest area under the curve value in predicting treatment efficacy (0.813, 95% confidence interval: 0.646-0.981, P < 0.001). Conclusions: Astigmatic vectorial analysis is an objective tool for longitudinal assessment of clinical outcomes in KC. Changes in the oblique components of corneal astigmatism might predict progression and treatment efficacy.
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    Correction: choroidal vascularity index as an indicator of vascular status of choroid, in eyes with nanophthalmos
    (Springer Nature, 2020) Aksoy, F. E.; Altan, C.; Demircan, A.; Tunç, U.; Demir, G.; Taskapılı, M.; N/A; Kesim, Cem; Doctor; Koç University Hospital; 387367
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    Effect of light backscattering from anterior segment structures on automated flare meter measurements
    (Sage Publications Ltd, 2022) Yalınbaş, Duygu; Yılmaz, Mervenur; Zeynep; Halim, Muhammad Sohail; Sepah, Yasir J.; Nguyen, Quan Dong; N/A; Hasanreisoğlu, Murat; Kesim, Cem; Uzunay, Nur Sena; Şahin, Afsun; Faculty Member; Teaching Faculty; Undergraduated Student; 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; 182001; 387367; N/A; 171267
    Background: To evaluate effect of maximal anterior cortical lens density, iris scatter and anterior chamber depth on laser flare photometry. Methods: Patients diagnosed with clinical uveitis were enrolled in the study. Clinical flare gradings were recorded upon the Standardization of Uveitis Nomenclature. Aqueous flare was measured with an automated device (Kowa FM700). Back-scattering from anterior cortical lens and anterior iris surface was calculated from Scheimpflug images. A curvilinear regression model was used to calculate estimated values for each clinical grade. These values were used to split cases in Group I (laser flare photometry lower than estimated) and Group II (laser flare photometry higher than estimated). Mean anterior chamber depth, pupil aperture, maximal anterior cortical lens density and iris scatter values were compared between two groups. A stepwise multiple regression analysis was performed to determine the effect of clinical flare gradings and ocular parameters on aqueous flare measurements. Results: The study included 228 eyes of 114 cases. Scheimpflug images were obtained from 105 eyes. Estimated aqueous flare measurements (in photons/milliseconds) were 4.87, 8.50, 14.81, 25.83, 45.04 and 136.93 for 0, 0.5+, 1+, 1.5+, 2+ and 3+ clinical flare respectively. Group II had higher maximal anterior cortical lens density than Group I (96.6 ± 37.1 vs 77.9 ± 17.1 pixel unit, p = 0.001). The measured aqueous flare was significantly related to clinical flare, maximal anterior cortical lens density and pupil aperture (adjusted R2: 0.480, p < 0.001). Conclusion: The back-scattered light from anterior cortical lens could affect laser flare photometry measurements. This effect might be quantified by Scheimpflug imaging.
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    Correlation of clinical aqueous flare grading to semi-automated flare measurements using laser flare photometry
    (Taylor & Francis, 2022) Halim, Muhammad Sohail; Onghanseng, Neil; Tran, Anh N. T.; Hassan, Muhammad; Yilmaz, Mervenur; Segawa, Asadu; Gurelik, Gokhan; Afridi, Rubbia; Ormaechea, Maria Soledad; Uludag, Gunay; Nguyen, Nam, V; Bae, Jeong Hun; Park, Jung Huynh; Do, Diana, V; Ibrahim, Mohamed A.; Sepah, Yasir J.; Quan Dong Nguyen; N/A; Hasanreisoğlu, Murat; Kesim, Cem; Faculty Member; Teaching Faculty; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; School of Medicine; 182001; 387367
    Purpose: To compare laser flare photometry (LFP) measurements of aqueous flare with Standardization of Uveitis Nomenclature (SUN) and modified SUN grading.Methods: In this prospective study with multicenter design, uveitis patients were classified according to SUN and modified SUN grading scales. LFP was performed with Kowa FM-700 flaremeter. Mean LFP values were compared with SUN and MSUN scores.Results: The study included 475 LFP measurements, of which 216, 48, 150, 31, 28 and 2 had 0, 0.5+, 1+, 1.5 +, 2+ and 3+ flare, respectively. LFP values were significantly different between each two consecutive steps for both clinical gradings (all P < .05). Cut-off values for modified SUN grading steps were defined as 5.7, 9.7, 15.7 and 43.2 for 0/0.5+, 0.5+/ 1+, 1+/1.5+ and 1.5/2+ borders of clinical flare, respectively.Conclusions: LFP proves to be an objective measurement in analyzing aqueous flare comparable to both SUN and MSUN clinical grading systems.
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    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
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    Identification of diagnostic and prognostic indicators of hypercoagulability in patients with pseudoexfoliation syndrome
    (Association for Research in Vision and Ophthalmology (ARVO), 2021) N/A; N/A; Narimanfar, Ghazal; Uğurel, Elif; Kesim, Cem; Zibandeh, Noushin; Albayrak, Özgür; Şahin, Afsun; Yalçın, Özlem; PhD Student; Resercher; Doctor; Resercher; Resercher; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Health Sciences; School of Medicine; N/A; N/A; N/A; School of Medicine; School of Medicine; N/A; N/A; Koç University Hospital; N/A; N/A; 387367; N/A; N/A; 171267; 218440
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    Henle fiber layer mapping with directional optical coherence tomography
    (Lippincott Williams & Wilkins, 2022) N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Computer Engineering; N/A; Kesim, Cem; Bektaş, Şevval Nur; Kulalı, Zeynep Umut; Yıldız, Erdost; Ersöz, Mehmet Giray; Şahin, Afsun; Demir, Çiğdem Gündüz; Hasanreisoğlu, Murat; Doctor; Undergraduate Student; Undergraduate Student; PhD Student; Doctor; Faculty Member; Faculty Member; Faculty Member; Department of Computer Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; School of Medicine; School of Medicine; N/A; School of Medicine; School of Medicine; College of Engineering; School of Medicine; Koç University Hospital; N/A; N/A; N/A; Koç University Hospital; N/A; N/A; N/A; 387367; N/A; N/A; N/A; 324533; 171267; 43402; 182001
    Purpose: To perform a macular volumetric and topographic analysis of Henle fiber layer (HFL) from retinal scans acquired by directional optical coherence tomography. Methods: Thirty healthy eyes of 17 subjects were imaged using the Heidelberg spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering, Heidelberg, Germany) with varied horizontal and vertical pupil entry. Manual segmentation of HFL was performed from retinal sections of horizontally and vertically tilted optical coherence tomography images acquired within macular 20 x 20 degrees area. Total HFL volume, mean HFL thickness, and HFL coverage area within Early Treatment for Diabetic Retinopathy Study grid were calculated from mapped images. Results: Henle fiber layer of 30 eyes were imaged, segmented and mapped. The mean total HFL volume was 0.74 +/- 0.08 mm(3) with 0.16 +/- 0.02 mm(3), 0.18 +/- 0.03 mm(3), 0.17 +/- 0.02 mm(3), and 0.19 +/- 0.03 mm(3) for superior, temporal, inferior, and nasal quadrants, respectively. The mean HFL thickness was 26.5 +/- 2.9 mu m. Central 1-mm macular zone had the highest mean HFL thickness with 51.0 +/- 7.6 mu m. The HFL coverage that have thickness equal or above to the mean value had a mean 10.771 +/- 0.574 mm(2) of surface area. Conclusion: Henle fiber layer mapping is a promising tool for structural analysis of HFL. Identifying a normative data of HFL morphology will allow further studies to investigate HFL involvement in various ocular and systemic disorders.