Yazar "Tekin, Kemal" seçeneğine göre listele
Listeleniyor 1 - 10 / 10
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Assessment of corneal topographic, tomographic, densitometric, and biomechanical properties of Fabry patients with ocular manifestations(Springer, 2020) Cankurtaran, Veysel; Tekin, Kemal; Cakmak, Ayse Idil; Inanc, Merve; Turgut, Faruk HilmiPurpose To investigate whether cornea verticillata affects corneal topography, tomography, densitometry, or biomechanics of Fabry patients with ocular manifestations and to compare these results with those obtained from healthy subjects. Methods This prospective, cross-sectional study included 23 Fabry patients (Fabry group) with cornea verticillata and the 37 age- and sex-matched healthy subjects (control group). After comprehensive ophthalmological examinations, corneal topography, tomography, and densitometry measurements were taken using Pentacam HR and corneal biomechanics were captured via Corvis ST for all participants. Results All the investigated topographic and tomographic values were similar in the eyes with Fabry disease (FD) and the controls (P > 0.05). The corneal densitometry values of patients with FD were statistically significantly higher in all the concentric zones and layers, except posterior 0-2 mm and posterior 2-6 mm zones, compared to the controls (P < 0.05). The mean values of A1 velocity, A2 velocity, deformation amplitude ratio, Corvis biomechanical index, tomographic and biomechanical index, and Stiffness parameter at the first applanation in the Fabry group were statistically significantly different compared to control group (P < 0.05). However, the mean values of A1 length, A2 length, and the biomechanically corrected intraocular pressure were similar between the groups (P = 0.317, P = 0.819, and P = 0.468; respectively). Conclusion Although cornea verticillata associated with FD is not considered to affect vision, it is associated with increased light backscattering and reduced corneal transparency as well as altered corneal biomechanical properties.Öğe Benzer Kırma Kusuru İçin Uygulanan Farklı Keratorefraktif Cerrahi Yöntemlerinin Keratometrik Değerler Üzerine Etkileri(2021) Özülken, Kemal; İlhan, Çağrı; Tekin, Kemal; Mumcuoğlu, Tarkan; Kaya, MahmutAmaç: Fotorefraktif keratektomi (PRK) ve laser in-situ keratomileusis (LASIK) gibi farklıkeratorefraktif yöntemlerle düzeltilen benzer büyüklükteki miyopik ve birleşik miyop astigmatik kırmakusurunun, korneal keratometrik güç üzerindeki etkilerinin benzer olup olmadığının araştırılmasıdır.Gereç ve Yöntemler: Bu geriye dönük, randomize olmayan, karşılaştırmalı klinik araştırmaOcak 2018 ve Haziran 2019 tarihleri arasında gerçekleştirilmiştir. Uygulanan cerrahiye göre olgularPRK (n=100) ve LASIK (n=76) olarak 2 gruba ayrılmıştır ve her bir hastanın sağ gözü çalışmayadahil edilmiştir. Olguların cerrahi öncesi ve cerrahi sonrası 6. aydaki klinik verileri göz önündebulundurularak sferik eşdeğerindeki (SE) azalma ile SEfark ve ortalama keratometrideki (Km) değişim ileKfark değerleri hesaplanmıştır. Kfark/SEfark hesaplaması ile birim SE değişiminin Km üzerindeki etkileriaraştırılmış ve gruplar arasında karşılaştırma yapılmıştır.Bulgular: PRK ve LASIK grupları arasında cinsiyet (p=0,348) ve yaş (p=0,768) bakımından anlamlıfark yoktu. SEfark değeri PRK grubunda -3,36 ± 1,46 D (-0,88 ile -6,50 D) iken LASIK grubunda -3,26± 1,41 D (-1 ile -6,13 D) idi ve gruplar arasında anlamlı fark yoktu (p=0,206). Kfark/SEfark parametresiPRK grubunda -0,87 ± 0,23 (-0,23 ile -1,53) iken LASIK grubunda -0,94 ± 0,46 (-0,32 ile -1,29) idive gruplar arasında anlamlı fark yoktu (p=0,169).Sonuç: Benzer büyüklükteki miyopik veya birleşik miyop astigmatik kırma kusuru düzeltmesindeuygulanan PRK ve LASIK cerrahilerinin Km değerindeki cerrahi ile elde edilen değişim üzerine olanetkileri benzerdir.Öğe Cumulative Effects of Smoking and Diabetes Mellitus on Corneal Endothelial Cell Parameters(Lippincott Williams & Wilkins, 2019) Cankurtaran, Veysel; Tekin, KemalPurpose: To compare the corneal endothelial morphometric properties and central corneal thickness (CCT) values in patients with diabetes mellitus (DM) and age-matched healthy subjects and to determine whether smoking increases the effects of DM on these corneal parameters. Methods: This prospective study included patients with type 2 DM and their age-matched controls. The smoking history of all participants was evaluated. Corneal endothelial cell properties including endothelial cell density (ECD), average cell area (AVG), coefficient of variation of cell area (CV), and percentage of hexagonal cells (HEX) were obtained using a noncontact specular microscope. Consequently, CCT was measured using an ultrasound pachymeter. Results: This research analyzed 153 subjects in the DM group and 146 subjects in the control group. There were no statistically significant differences in the age, sex, and smoking status of the participants in 2 groups (P> 0.05). The corneal endothelial cell measurements including ECD, AVG, CV, and HEX did not show any statistically significant differences between these groups (P> 0.05). However, CCT of patients with DM was statistically significantly thicker than that of the controls (P = 0.005). The ECD values of the smokers with DM (2435 6 325 cells/mm(2)) were statistically significantly lower than those of nonsmoker healthy subjects (2559 6 279 cells/mm(2) P = 0.008). However, the AVG, CV, HEX, and CCT values of the smokers with DM were not statistically significantly different compared with nonsmoker healthy subjects (P> 0.05). Conclusions: Although neither only DM nor only smoking has a statistically significant effect on corneal endothelial morphometric properties, coexistence of DM and smoking causes a significant decrease in ECD.Öğe Effects of a Single Dose of Topical Brimonidine 0.15% on Anterior Segment Morphology, Pupil Characteristics, and Choroidal Thickness in Healthy Subjects(Lippincott Williams & Wilkins, 2021) Cankurtaran, Veysel; Tekin, KemalPurpose: To investigate the effects of a single dose of brimonidine 0.15% on anterior segment morphology, pupil characteristics, and choroidal blood flow in treated and untreated eyes of healthy subjects and to compare the results obtained with those in another healthy volunteer group. Methods: Participants were classified as study and control groups. The eyes in the study group were randomized. Only one eye received one drop of brimonidine (treated eyes), and the contralateral eye received single dose of sodium hyaluronate (untreated eyes). In addition, only right eyes of control subjects, who had single dose of sodium hyaluronate to both eyes, were analyzed (control eyes). Anterior segment parameters including central corneal thickness (CCT), aqueous depth, anterior chamber volume, iridocorneal angle (ICA), horizontal anterior chamber diameter, and pupil measurements including scotopic, mesopic, photopic, and dynamic pupil diameters (PDs) were performed with Sirius Scheimpflug camera. Choroidal thickness (CT) measurements were taken with optical coherence tomography. These measurements were taken at baseline and repeated 1 hour after the dosing. Results: Only the treated eyes had significantly thicker CCT and wider ICA values after instillation of brimonidine. Static and dynamic PD values of treated eyes and even untreated eyes significantly decreased after brimonidine. However, brimonidine has no significant effect on CT measurements. Conclusion: A single dose of brimonidine causes thickening in CCT and widening in ICA values in treated eyes. In addition, it has significant effect to decrease the scotopic, mesopic, photopic, and dynamic PD values in treated and even contralateral eyes while has no effect on choroidal blood flow.Öğe Evaluation of static and dynamic pupil characteristics in hyperopic anisometropic amblyopia(Sage Publications Ltd, 2019) Yetkin, Esat; Tekin, Kemal; Kiziltoprak, Hasan; Sekeroglu, Mehmet Ali; Cankurtaran, Veysel; Yasar, Hakan HalitPurpose: The aim of this study is to perform a comparison of static and dynamic pupillometry measurements in patients with hyperopic anisometropic amblyopia and age-matched controls. Methods: This prospective cross-sectional study consisted of 38 patients with hyperopic anisometropic amblyopia and 80 control subjects. A quantitative pupillometry system was used to evaluate the pupil characteristics of higher hyperopic eyes (Group 1), the fellow eyes (Group 2), and healthy eyes (Group 3). Static pupillometry measurements were taken including scotopic pupil diameter, mesopic pupil diameter, low-photopic pupil diameter, and high-photopic pupil diameter. Subsequently, dynamic pupillometry measurements were taken including resting diameter, amplitude of pupil contraction, latency of pupil contraction, duration of pupil contraction, velocity of pupil contraction, latency of pupil dilation, duration of pupil dilation, and velocity of pupil dilation. Results: Groups 1 and 2 had statistically significantly lower scotopic and high-photopic pupil diameter values compared with Group 3 (p < 0.05). The amplitude of pupil contraction values were also statistically significantly lower in Groups 1 and 2 compared with Group 3 (p = 0.001 and p = 0.003). However, there were no significant differences between the study and the control eyes with respect to mesopic and high-photopic pupil diameter, resting diameter, latency of pupil contraction, duration of pupil contraction, velocity of pupil contraction, latency of pupil dilation, duration of pupil dilation, and velocity of pupil dilation values (p > 0.05, for all). Conclusion: Static and dynamic pupil characteristics of higher hyperopic eyes and their fellow eyes are similar. This may support that amblyopia is not a monocular disorder, but can affect both eyes.Öğe Evaluation of topographic, tomographic, topometric, densitometric, and aberrometric features of cornea with pentacam HR system in subclinical keratoconus(Springer, 2021) Ozkan, Haci Hasan; Koc, Mustafa; Kiziltoprak, Hasan; Tekin, Kemal; Aydemir, EmrePurpose To investigate topographic, tomographic, topometric, densitometric, and aberrometric parameters in subclinical keratoconus with the Pentacam HR imaging system. Methods Data of 3128 patients were evaluated, finding in 108 patients clinical keratoconus in one eye and subclinical keratoconus in the other. Corneal topographic, tomographic, topometric, densitometric, and aberrometric values obtained using the Pentacam HR imaging system were compared between clinical keratoconus, subclinical keratoconus, and normal eyes. Results Comparing eyes with subclinical keratoconus and the control group, while flat K, horizontal coma, horizontal trefoil, and vertical trefoil values were similar (p > 0.05 for each), all other parameters were significantly different (p < 0.05 for each). Densitometry values of eyes with subclinical keratoconus were significantly higher in all layers of the 0-2 mm annular area and in the anterior and central layers of the 2-6 mm annular area compared to the control group (p < 0.05 for each). According to the receiver operating characteristic curve analysis, the densitometry region with the largest area under the curve was the anterior layer of the 0-2 mm annular area. The sensitivity in this region was 79.4% and the specificity 73.2% in distinguishing eyes with subclinical keratoconus from normal eyes when 19.3 GSU was considered the threshold. Conclusion Corneal densitometry values in the 0-2 and 2-6 mm annular areas, especially in the anterior layers, are parameters that can be used to predict and distinguish subclinical keratoconus from normal eyes.Öğe An objective evaluation of lens transparency after vitrectomy surgery with different intravitreal tamponades(Springer, 2022) Yalcinsoy, Kubra Ozdemir; Erol, Yasemin Ozdamar; Tekin, Kemal; Tekin, Merve Inanc; Sonmez, KenanPurpose To evaluate and compare the effects of different intraocular tamponade agents on lens density after vitrectomy. Methods The participating patients were divided into four groups according to the tamponade agent used: a sulfur hexafluoride (SF6) group, a perfluoropropane (C3F8) group, a silicone oil group, and a no tamponade group. Lens density measurements were performed preoperatively and two weeks, one month, and three months postoperatively using a Pentacam HR device with a Scheimpflug camera. The postoperative values were compared with the preoperative baseline values, also the values were compared between the four groups. Results The study included 82 eyes (82 patients). In the SF6 group, lens density significantly increased in all zones two weeks and one and three months postoperatively (all P < .05). In the C3F8 group, lens density significantly increased in all zones three months postoperatively (all P < .01). In the silicone oil group, the zone 1, zone 2, and average lens density (ALD) value significantly increased one and three months postoperatively (all P < .05). In the no tamponade group, the zone 1, zone 2, and ALD values significantly increased three months postoperatively (all P < .05). There were no significant differences between the four groups in any zone either preoperatively or postoperatively (all P > .05). Conclusions Although increases in lens density were observed earlier in the tamponade groups than in the no tamponade group, between the groups over the follow-up period were no differences. We need the development of new surgical methods and materials to prevent post-vitrectomy lens damage in the future.Öğe Preeklampside Retinal Vasküler Sistemin Optik Koherens Tomografi Anjiyografi ile Değerlendirilmesi(2021) Cankurtaran, Veysel; Tekin, Kemal; İnanç, Merve; Dolapçıoğlu, Kenan SerdarAmaç: Çalışmada preeklampsinin, retinal vasküler sistem üze-rindeki etkis ini opt ik koherens tomografi anjiyograf i ile değerlendir-mek ve elde edilen verileri sağlıklı gebelerle ve gebe olmayan sağlıklı kadınlarla karşılaştırmak amaçlanmıştır. Gereç ve Yöntemler: Çalış-maya preeeklampsi tanılı gebeler (18 kişi, Grup 1), sağlıklı gebeler (24 kişi, Grup 2) ve gebe olmayan sağlıklı kadın olgular (25 kişi, Grup 3) dâhil ed ilmiş tir. Tüm katılımcılara, optik koherens tomografi anji yo-grafi de dâhil kapsamlı bir oftalmolojik muayene yapılmış ve optik ko-herens tomografi anjiyografi parametreleri gruplar aras ında karşılaştırılmıştır. Bulgular: Her 3 grupta, ortalama yaş açısından ista-tistiksel anlamlı fark saptanmamıştır (p=0,755). Ortalama yüzeyel fo-veal vasküler dansite ve derin foveal vasküler dansite açısından, her 3 grup arasında istat istiksel anlamlı farklı lık saptanmıştır (sırasıyla p=0,001; p<0,001). Grup 1 ve Grup 2'deki hastalarda, ortalama yüze-yel foveal vasküler dansite ve derin foveal vasküler dansite Grup 3'teki olgulara kıyasla istatistiksel anlamlı düzeyde düşük olarak izlenmiştir (p<0,05). Grup 1 ve Grup 2'deki hastaların, iki li karşılaştırılmasında ise ortalama yüzeyel foveal vasküler dansitede anlamlı farklılık sap-tanmazken; ortalama derin foveal vasküler dansite Grup 1'de istatistik-sel anlamlı düzeyde düşük olarak bulunmuştur (sırasıyla p=0,626; p=0,015). Sonuç: Preeklampsinin, retinal vasküler sistem üzerinde an-lamlı etkilenmelere neden olduğu saptanmıştır.Öğe Retinal Microcirculation in Predicting Diabetic Nephropathy in Type 2 Diabetic Patients without Retinopathy(Karger, 2020) Cankurtaran, Veysel; Inanc, Merve; Tekin, Kemal; Turgut, FarukPurpose: To evaluate retinal thicknesses and retinal microcirculation in healthy controls and in diabetic patients with or without microalbuminuria. Methods: Eighty-six diabetic patients without diabetic retinopathy (DR) (44 normoalbuminuric, 42 microalbuminuric) and 51 healthy controls were enrolled in this cross-sectional, prospective study. Optical coherence tomography (OCT) and OCT angiography (OCTA) were performed. Correlations between OCTA parameters with mean urinary albumin levels were evaluated. Results: The mean vessel densities of superficial capillary plexus (SCP), whole disc, and peripapillary area were significantly decreased in patients with microalbuminuria compared to patients with normoalbuminuria and controls (p < 0.05 for all). The mean vessel density of deep capillary plexus was significantly reduced in patients with microalbuminuria compared to controls (p < 0.05 for all). There were no significant differences in retinal thickness between groups (p > 0.05). Both duration of diabetes and urinary albumin levels were significantly and moderately correlated with mean vessel density of whole SCP in diabetic patients (r = 0.330, p = 0.021; r = 0.356, p = 0.017, respectively). Conclusion: Diabetic eyes without clinically detectable DR show impaired retinal microcirculation. Microalbuminuria is associated with alterations of retinal microcirculation in diabetic patients without DR. Evaluation of retinal microcirculation is likely useful for detecting early changes related to microvascular complications in type 2 diabetic patients.Öğe Use of automated quantitative pupillometric evaluation for monitoring the severity of diabetic retinopathy(Consel Brasil Oftalmologia, 2021) Cankurtaran, Veysel; Ilhan, Cagri; Tekin, Kemal; Citirik, Mehmet; Dirican, Emre; Gurkan, ErenPurpose: We aimed to evaluate the use of automated quantitative static and dynamic pupillometry in screening patients with type 2 diabetes mellitus and different stages of diabetic retinopathy. Method: 155 patients with type 2 diabetes mellitus (diabetes mellitus group) were included in this study and another 145 age- and sex-matched healthy individuals to serve as the control group. The diabetes mellitus group was divided into three subgroups: diabetes mellitus without diabetic retinopathy (No-diabetic retinopathy), nonproliferative diabetic retinopathy, and proliferative diabetic retinopathy. Static and dynamic pupillometry were performed using a rotating Scheimpflug camera with a topography-based system. Results: In terms of pupil diameter in both static and dynamic pupillometry (p <0.05), statistically significant differences were observed between the diabetes mellitus and control groups and also between the subgroups No-diabetic retinopathy, nonproliferative diabetic retinopathy, and proliferative diabetic retinopathy subgroups. But it was noted that No-diabetic retinopathy and nonproliferative diabetic retinopathy groups have showed similarities in the findings derived from static pupillometry under mesopic and photopic conditions. The two groups also appeared similar at all points during the dynamic pupillometry (p>0.05). However, it could be concluded that the proliferative diabetic retinopathy group was significantly different from the rest of the subgroups, No-diabetic retinopathy and nonproliferative diabetic retinopathy groups, in terms of all the static pupillometry measurements (p<0.05). The average speed of dilation was also significantly different between the diabetes mellitus and control groups and among the diabetes mellitus subgroups (p<0.001). While weak to moderate significant correlations were found between all pupil diameters in static and dynamic pupillometry with the duration of diabetes mellitus (p<0.05 for all), the HbAlc values showed no statistically significant correlations with any of the investigated static and dynamic pupil diameters (p>0.05 for all). Conclusion: This study revealed that the measurements derived from automated pupillometry are altered in patients with type 2 diabetes mellitus. The presence of nonproliferative diabetic retinopathy does not have a negative effect on pupillometry findings, but with proliferative diabetic retinopathy, significant alterations were observed. These results suggest that using automated quantitative pupillometry may be useful in verifying the severity of diabetic retinopathy.
