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Öğe Can vitreous reflux affect the short-term treatment response after intravitreal ranibizumab injection?(Taylor & Francis Inc, 2021) Uyar, Enes; Ulaş, Fatih; Alkan, YunusPurpose The aim of this study was to evaluate the effect of vitreous reflux (VR) on the short-term effect of intravitreal ranibizumab injection. Materials and Methods The study included 181 eyes of 81 age-related macular degeneration (AMD) and 100 diabetic macular edema (DME) patients. Treatment response was evaluated by measuring central macular thickness (CMT) as well as 1 mm and 3 mm central macular thicknesses (MT1 and MT3). Patients were grouped as; Group 1: no VR, Group 2: <3 mm VR, and Group 3: >3 mm VR according to conjunctival bleb diameters. The data were analyzed using variance, correlation and regression analyses. Results In AMD patients, reduction of CMT values following the treatment were 88.3 +/- 110.6 mu m in Group 1, 85.6 +/- 158.7 mu m in Group 2, and 93.1 +/- 92.2 mu m in Group 3. Likewise, in DME patients, it was 82.4 +/- 88.4 mu m, 72.9 +/- 109.9 mu m, and 73.7 +/- 113.7 mu m, respectively. Reduction of MT1 values after the treatment were 47.4 +/- 72.6 mu m, 36.0 +/- 131.9 mu m, and 36.7 +/- 114.4 mu m in AMD patients, and 33.3 +/- 72.5 mu m, 36.6 +/- 90.2 mu m, and 46.9 +/- 83.4 mu m in DME patients. In all comparisons among groups of VR, macular thickness (MT) change did not exhibit significant difference following an intravitreal ranibizumab treatment (p> .05). Conclusion We found that the increase in VR amount did not adversely affect the decrease in MT after intravitreal ranibizumab treatment in AMD and DME patients.Öğe Comparison of the Effect of Different Treatment Doses of Intrastromal Vancomycin in a Rabbit Model of Methicillin-Resistant Staphylococcus Aureus (MRSA) Keratitis(Taylor & Francis Inc, 2024) Bayrak, Abdullah; Celebi, Serdal; Avcioglu, Fatma; Alkan, YunusPurposeTo compare the effect of different doses of vancomycin on a rabbit model of MRSA keratitis.MethodsTwenty-four eyes of 24 New-Zealand White rabbits were included in the study. MRSA keratitis was applied to 24 left eyes of 24 New Zealand rabbits. Twenty-four hours after MRSA inoculation; 0.5 mg/0.1 mL, 1 mg/0.1 mL, and 2 mg/0.1 mL and balanced salt solution were administered to 6 rabbits in 4 groups, respectively.ResultsThe effect of different doses of vancomycin on reducing bacterial load was found to be statistically significant when each was compared to the control group (p = 0.006). When comparing the dosages with each other, no superiority was shown (p = 0.297, p = 0.749, p = 0.262 respectively). There was a significant increase in the posttreatment total clinical score in the control and 2 mg/0.1 mL groups compared to the pretreatment score (p = 0.001, p = 0.001 respectively).ConclusionIt is emphasized that necessary treatment can be achieved by administering less antibiotic (0.5 mg/0.1 mL) to the corneal intrastromal area.Öğe Comparison of the short-term effect of coffee, energy drink, and water on the eyes in young healthy subjects(Springernature, 2023) Toprak, Güvenç; Alkan, YunusPurpose: We aim to compare the short-term effects of energy drink (ED), coffee, and water on the eyes of young healthy male subjects.Materials and methods: The right eyes of 30 healthy male subjects were included in this study. We measured the intraocular pressure (IOP), mean arterial pressure (MAP), retinal thickness (RT), choroidal thickness (CT), and retinal nerve fiber layer (RNFL) thickness using spectral domain optical coherence tomography (SD OCT). The measurements for RT and CT were taken at the fovea as well as 1,500 mu m nasal and temporal to the fovea. The measurements of the subjects were performed on the first day before water consumption and at 30 minutes and 60 minutes following intake of 250 mL of water. Measurements were repeated at the same regime on the second day after drinking 250 mL of coffee containing an equal concentration of caffeine in ED (37.5 mg) and on the third day after drinking 250 mL of ED. Repeated measures one-way analysis of variance test was used for statistical analysis.Results: No significant difference was found for ocular perfusion pressure (OPP), MAP, RT, and IOP between the measurements taken on three consecutive days (p>0.05 for all). The CT values for the central, nasal, and temporal segments were significantly reduced in 0-30 and 0-60 minutes following coffee and ED intake (the range of p-value was <0.001-0.027).Conclusions: Both coffee and ED intake caused acute and significant decreases in CT that persisted for one hour in young healthy male subjects. The impact of ED intake on CT was attributed mainly to its caffeine content.Öğe Evaluation and comparison of optical coherence tomography angiography (OCTA) parameters in normal and moderate myopic individuals(Elsevier, 2024) Toprak, Güvenç; Ulaş, Fatih; Kaymaz, Abdulgani; Soydan, Adem; Kaplan, Abdulfatih; Alkan, Yunus; Özdemir, Buse; Bayrak, AbdullahObjective: The objective of this study was to evaluate and compare Optical Coherence Tomography Angiography (OCTA) parameters in patients with moderate myopia and healthy individuals retrospectively. Methods: A total of 80 male individuals aged 18-20 years were included in the study with 40 moderate myopic and 40 healthy persons. All participants underwent detailed ocular examination including refraction, intraocular pressure (IOP), visual acuity, biomicroscopy, OCTA measurement and optic biometry measurement. Retinal, retinal nerve fiber layer and choroidal layer thicknesses were evaluated in mu m with the help of the software available in the OCTA device. Results: The mean axial length (24.32 +/- 0.53 mm) was statistically significantly higher in the moderate myopic group (24.32 mm) compared to the healthy group (23.33 +/- 0.61 mm) (p < 0.001). Spherical equivalent (SE) was found as -3.79 +/- 0.91 D in the moderate myopic group and -0.22 +/- 0.32 D in the healthy group (p < 0.05). The mean superficial foveal mean density (FovSupMVD) and the mean deep foveal mean density (FovDepMVD) were statistically significantly lower in the moderate myopic group than in the healthy group (both, p < 0.001). The mean retinal temporal thickness (RTt) was statistically significantly lower in the moderate myopic group (p = 0.017). There was a mild negative correlation between axial length and FovSupMVD, FovDepMVD in myopes. In axial length ROC analysis, the cutoff value for moderate myopes was found to be 24.15 mm. Mean superficial foveal mean density (FovSupMVD) and mean deep foveal mean density (FovDepMVD), mean retinal temporal thickness (RTt) were significantly lower in the group above 24.15 mm axial length compared to the group below 24.15 mm axial length (all three, p < 0.001). Foveal avascular zone was significantly higher in the group above 24.15 mm axial length (p = 0.016) Conclusion: The results of our study indicate that the mean axial length and spherical equivalent were significantly higher, while retinal temporal thickness, the mean superficial foveal mean density and the mean deep foveal mean density were significantly lower in patients with myopia up to -6.0 D compared to the healthy individuals.Öğe Preoperative evaluation of white cataracts with the pentacam(Elsevier, 2024) Toprak, Güvenç; Alkan, Yunus; Bayrak, AbdullahPurpose: To evaluate the use of the Pentacam to analyse the presence or absence of fluid pockets under the anterior capsule and their significance in terms of surgical management and prevention of complications. Settings: Abant & Idot;zzet Baysal University Hospital, Bolu, Turkey DESIGN: Randomized, masked, prospective design METHODS: 60 patients with mature cataracts underwent standard phacoemulsification (Phaco) and intraocular lens (IOL) implantation. Patients were divided into 3 groups. Group 1 underwent Phaco+IOL implantation without imaging by Pentacam. Group 2 had fluid detected in Pentacam imaging before the operation and underwent Phaco+IOL implantation with Brazilian method. Group 3 had no fluid detected in Pentacam imaging before the operation and underwent standart Phaco+IOL implantation operation. Results: When the complication rates of 3 different groups were examined separately, they were found to be 15 % in group 1; 5 % in group 2 and 5 % in group 3, respectively. When compared in pairs as Group 1-2, 1-3, and 2-3, respectively (p < 0.01), (p < 0.01), (p > 0.05). The nuclear density of Group 2 and Group 3 was measured, resulting in 30.2 % and 29.6 %, respectively (P = 0.614). Lens thickness, patients with fluid (+) had a thickness of 5.35 mm, while patients with fluid (-) had a thickness of 3.96 mm (p < 0.05). Conclusion: Patients who are not imaged with pentacam before surgery experience more complications than other groups because the presence of fluid is unknown. Central lens thickness was higher in patients with fluid, and there was no significant difference in nuclear density between the groups with and without fluid. Pentacam can show the presence of supcapsular fluid and we recommend that imaging tools be more widely used in cataract surgery. We think that this will enable surgeons to make a more accurate surgical planning and reduce the risk of complications.Öğe The relationship between Choroidal Vascular Index and non-invasive ultrasonographic atherosclerosis predictors(Elsevier, 2024) Bayraktar, Muhammet Fatih; Toprak, Guvenc; Alkan, YunusBackground: This study explores the intricate connections between choroidal vascular index (CVI) and noninvasive ultrasonographic atherosclerosis predictors, shedding light on the potential links between ocular vascular dynamics and systemic cardiovascular health. Methods: We conducted a cross-sectional analysis of 81 participants, assessing CVI, intima-media thickness (IMT), extra -media thickness (EMT), and the PATIMA index. The presence of coronary artery disease (CAD) was also evaluated. Statistical methods included descriptive statistics, t -tests for group comparisons, Spearman correlation analysis, and receiver operating characteristic (ROC) curve analysis. Results: Our findings revealed that patients with CAD had lower CVI values compared to those without CAD, underscoring a potential association between CVI and CAD. Significant negative correlations were observed between CVI and IMT, EMT, PATIMA, and CAD. ROC curve analysis identified optimal CVI cutoff values for hypertension and CAD detection, showcasing its potential as a diagnostic marker. Discussion: Our results align with existing literature on ocular vascular changes, supporting the notion that CVI may be a promising indicator of systemic vascular conditions. The study contributes to the broader understanding of the relationships between ocular and cardiovascular health, providing a foundation for future research and clinical applications. Conclusion: The study suggests that CVI holds clinical relevance as a non-invasive marker for identifying systemic conditions, offering insights into the fields of neurology, physical therapy, and rehabilitation. Addressing its limitations, this research encourages further investigation into the multifaceted connections between CVI and atherosclerosis predictors.Öğe Role of epicardial fat thickness for prediction of proliferative diabetic retinopathy(Springer India, 2023) Sincer, Abide; Kaygusuz, Tuba; Alkan, Yunus; Coşgun, Mehmet; Doğan, Ümit; Ulaş, Fatih; Sincer, İsa; Güneş, YılmazPurpose Plenty of factors including inflammation are responsible for development of diabetic retinopathy (DR). Epicardial fat produces adipokines, cytokines and inflammatory products. Monocyte count to high density lipoprotein (HDL) ratio (MHR) has been recently suggested as an inflammatory marker. Methods Epicardial fat thickness (EFT) and MHR were analyzed in 36 diabetics without DR (NDR), 35 diabetics with proliferative DR (PDR) and 41 diabetics with nonproliferative DR patients (nonPDR). Results Monocyte counts, HDL, mean MHR and EFT values of NDR, nonPDR and PDR groups were significantly different. One-way analysis of variance test with post hoc Tukey test revealed that the significance of differences in MHR and EFT were dependent on the differences between NDR and PDR (p<0.001 for both) and nonPDR and PDR groups (pp=0.001). The differences between NDR and nonPDR (p=0.81 and p=0.06) were not significant. MHR and EFT were significantly positively correlated with PDR (r=0.453, pr=0.394, p<0.001) and negatively correlated with NDR (r=-0.256, p=0.006 and r= -0.380, p<0.001). Only EFT was found to be independently associated with PDR (p=0.002, 95% CI: OR: 1.643 (1.206-2.237)). An EFT value of >5.90 mm classified the presence of PDR with a sensitivity 74% and specificity of 61% (AUC = 0.750, 95% CI, 0.658-0.843), and a MHR value of >12.8 ratio classified the presence of PDR with a sensitivity of 83% and a specificity of 79% (AUC = 0.811, 95% CI, 0.728-0.893). Conclusion We suggest that MHR and EFT were significantly increased in proliferative DR, and increased EFT may predict the presence of PDR in type 2 DM.Öğe Tavşanlarda metisilin dirençli staphylococcus aureus keratit modelinde topikal vankomisin ve povidon iyot tedavilerinin etkinliğinin karşılaştırılması(Bolu Abant İzzet Baysal Üniversitesi, 2021) Alkan, Yunus; Kaymaz, AbdulganiÇalışmanın amacı, tavşanlarda oluşturulan metisilin dirençli Staphylococcus aureus (MRSA) keratit modeli üzerinde, topikal vankomisin ile povidon iyot (PI) etkinliklerini karşılaştırmaktır. Bu amaçla 24 tavşanın sağ göz kornea santraline 103 CFU içeren 0,1 mL MRSA suşu uygulanarak keratit modeli oluşturulduktan sonra, her grupta 6 tavşan bulunacak şekilde, tavşanlar 4 gruba ayrılmıştır. Birinci gruptaki 6 göz kontrol grubu olarak kabul edilmiş ve dengeli tuz solüsyonu (%0.9 NaCl) uygulanmıştır. İkinci gruba topikal vankomisin, üçüncü gruba topikal PI, dördüncü gruba ise topikal vankomisin ve PI uygulanmıştır. Tedavi sonrası tavşanların korneaları, ötenaziyi takiben mikrobiyolojik analiz için vakumlu trepan yardımıyla çıkarılmıştır. Ayrıca tedaviden önce ve sonra tüm kornealar klinik olarak kemozis, konjonktival enjeksiyon, iritis, fibrin, hipopiyon, epitel erozyonu, korneal infiltrat ve korneal ödem parametreleri açısından incelenip puanlanmıştır. Bakteriyel yük en yüksekten en düşüğe doğru, kontrol grubunda 7.63 ± 0.82 log10 CFU/g, PI grubunda 6.95 ± 1.66 log10 CFU/g, topikal vankomisin + PI grubunda 4.67 ± 0.77 log10 CFU/g, topikal vankomisin grubunda 4.33 ± 0.71 log10 CFU/g olarak sıralanmıştır. MRSA keratitinin tedavi öncesi ve sonrası gruplardaki toplam klinik skorlar karşılaştırıldığında; kontrol grubunda toplam klinik skor: 6.83 ± 1.16'ya karşı 12.16 ± 1.60 (p=0.001), vankomisin grubunda toplam klinik skor 6.16 ± 0.98'e karşı 6.33 ± 1.03 (p=0.695), povidon iyot grubunda toplam klinik skor 7.00 ± 1.09'a karşı 12.00 ± 1.67 (p=<0.001), vankomisin + PI grubunda toplam klinik skor 6.33 ± 0.81'e karşı 8.16 ± 0.75 (p=0.002) bulunmuştur. Tedavi sonrası grupların klinik skorlarını incelediğimizde; kontrol grubunda klinik skorların belirgin olarak kötüleştiği, vankomisin ile tedavi edilen grupta iritis, hipopiyon ve korneal infiltrat parametrelerindeki skorların düşüklüğü dikkat çekmektedir. PI ile tedavi edilen gruplarda ise özellikle kemozis, konjonktival enjeksiyon ve epitel erozyonu paremetrelerindeki yüksek skorlar göze çarpmaktadır. Sonuç olarak, MRSA'da topikal vankomisinin bakteriyel yükü anlamlı şekilde azalttığı görülmüştür. Ancak PI bakteriyel yükü azaltmada etkili bulunmamış, üstelik oküler yüzey üzerinde toksik etki gösterdiği izlenmiştir. Ayrıca vankomisine ek olarak PI kullandığımızda tedavi etkinliğinde artış saptanmamıştır.Öğe Topical vancomycin is more efficient than povidone-ıodine treatment in controlling bacterial growth in methicillin-resistant staphylococcus aureus keratitis model in rabbits(Taylor & Francis Inc, 2024) Alkan, Yunus; Kaymaz, Abdulgani; Behçet, Mustafa; Bayrak, AbdullahPurpose: To evaluate the efficacy of topical vancomycin and povidone iodine (PI) application on methicillin-resistant Staphylococcus aureus (MRSA) keratitis model in rabbits. Methods: MRSA keratitis was induced by injecting 0.1 mL MRSA containing 1000 colony-forming units (CFU) into central cornea of right eyes of 24 New Zealand White rabbits. Animals were divided into four groups (n = 6): control (treated with balanced salt solution), 50 mg/mL topical vancomycin, 5% topical PI, and combination; examined before and after treatment, and corneal tissues were harvested for analysis at 9th hour of treatment. Results: Bacterial load was determined as: 7.63 +/- 0.82 log10 CFU/g in control group, 6.95 +/- 1.66 log10 CFU/g in PI group, 4.67 +/- 0.77 log10 CFU/g in combination group, and 4.33 +/- 0.71 log10 CFU/g in vancomycin group (p = 0.001). Median of total clinical score increased significantly from 7 [range: 5-8] to 11.5 [range: 11-15] (p = 0.001) in control group, did not change (6 [range: 5-8] to 7 [range: 5-7]; p = 0.695) in vancomycin group, increased significantly from 7 [range: 5-8] to 12.5 [range: 10-14] (p < 0.001) in PI group, increased significantly from 6.5 [range: 5-7] to 8 [range: 7-9] in combination group (p = 0.002). Post-treatment clinical scores for chemosis, conjunctival injection, iritis, hypopyon, epithelial erosion, and corneal infiltrate were significantly lower in vancomycin-treated groups compared to others (p < 0.05). In PI-treated groups, especially scores for chemosis, conjunctival injection, epithelial erosion and corneal infiltrate were significantly higher than vancomycin (p < 0.05). Conclusion: Topical vancomycin significantly inhibited bacterial growth in MRSA keratitis. However, PI was ineffective in controlling this growth; additionally, exerted toxic effect on ocular surface. When vancomycin was combined with PI, no additional increase in efficacy of treatment was detected compared to only vancomycin.
