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    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, Yunus
    PurposeTo 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.
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    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, Abdullah
    Objective: 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.
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    Peripheral Facial Paralysis in a Newborn with Charge Syndrome
    (2022) Özdemir, Melike; Ergeldi, Gülçin; Bayrak, Abdullah; Karahan, Eyup; Arman, Ayşegül
    CHARGE Syndrome is a genetic disorder that affects many organs. Approximately two-thirds of the cases have CHD7 mutations. Most individuals with this syndrome have a coloboma in their eyes. Coloboma can be found in one or both eyes and may impair visual functions depending on its size and location. Moreover, patients with this syndrome often have cranial nerve abnormalities. In this infant, peripheral facial paralysis was detected in addition to the eye coloboma, choanal atresia, heart defects, growth retardation, and ear anomalies, which are the main characteristic findings of CHARGE Syndrome. The chorioretinal coloboma in our case was present in both eyes and included optic discs. He had findings such as facial weakness on the left side, lagophthalmos, and flattening of the nasolabial fold due to peripheral facial paralysis. Lubrication therapy and eye closure treatment at night were started to protect the corneas of this patient. The cases with CHARGE Syndrome should be kept under ophthalmologic control against the risk of retinal detachment, amblyopia, and refractive errors that may occur in the future. We should be careful about the VII., VIII., IX. and X. cranial nerves dysfunctions which cause severe morbidity such as lagophthalmos, deafness, the difficulty of feedings in these cases.
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    Preoperative evaluation of white cataracts with the pentacam
    (Elsevier, 2024) Toprak, Güvenç; Alkan, Yunus; Bayrak, Abdullah
    Purpose: 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.
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    Tavşan gözlerinde metisilin dirençli staphylococcus aureus keratit modelinde intrastromal vankomisinin farklı tedavi dozlarının etkinliğinin karşılaştırılması
    (Bolu Abant İzzet Baysal Üniversitesi, 2022) Bayrak, Abdullah; Çelebi, Serdal
    Bu çalışmada, metisilin dirençli Staphylococcus aureus (MRSA) etkenli bakteriyel keratit tedavisinde, korneal intrastromal vankomisinin farklı tedavi dozlarının etkinliklerinin karşılaştırılması amaçlanmıştır. Bu amaçla 24 tavşanın sol göz kornea santraline 103 CFU içeren 0,1 mL MRSA suşları, 30 gauge enjektör ile intrastromal ekimi yapıldıktan sonra, her grupta altı adet olacak şekilde, tavşanlar 4 gruba ayrılmıştır. Keratit modeli oluşması için 24 saat beklenilmiştir ve tüm gruplarda keratit modeli oluştuğu gözlendikten sonra ikinci aşamaya geçilmiştir. Birinci gruptaki 6 göz kontrol grubu olarak kabul edilmiş ve intrastromal dengeli tuz solüsyonu uygulanmıştır. İkinci grup tavşanların sol kornealarına tek doz 0,5 mg/0,1 mL intrastromal vankomisin; üçüncü grup tavşanların sol kornealarına tek doz 1 mg/0,1 mL intrastromal vankomisin; dördüncü grup tavşanların sol kornealarına tek doz 2 mg/0,1 mL intrastromal vankomisin enjeksiyonu yapılmıştır. Bu enjeksiyonlardan sonra 24 saat beklenilmiştir ve tavşanların hiçbirinde olası komplikasyon görülmemiştir. Sonrasında son safha olan ötenaziyi takiben vakumlu trepan yardımıyla kornealar çıkarılıp, mikrobiyoloji laboratuvarına gönderilmiştir. Bakteriyel yük en fazladan en aza doğru şu şekilde sıralanmıştır; kontrol grubu (7,13±1,27 log10 CFU/g), 0,5 mg/0,1 mL intrastromal vankomisin grubu (4,54±0.57 log10 CFU/g), 2 mg/0,1 mL intrastromal vankomisin grubu (4,49±0.85 log10 CFU/g) ve 1 mg/0,1 mL intrastromal vankomisin grubu (4,21±0.83 log10 CFU/g). Çalışmamızdaki her bir kornea morfolojik olarak da incelenmiştir. Bu işlemi yaparken sekiz farklı parametre (kemozis, konjonktival injeksiyon, iritis, fibrin, hipopiyon, epitel erazyonu, korneal infiltrat, korneal ödem) klinik bir puanlama sistemi (0:yok; 1:minimal; 2: hafif; 3:orta; 4:ciddi) kullanılarak iki farklı gözlemci tarafından (A.B. ve Y.A.) değerlendirilmiştir. Puanlama işlemi sırasında hem dışarıdan morfolojik gözlem yolu hem de biyomikroskopi kullanılmıştır. Bu amaçla keratit modellemesi yapıldıktan sonraki 24.saatte (tedavi öncesi) ve 48.saatte (tedavi sonrası) sonuçları değerlendirilip kaydedilmiştir. Bu skorlar, hem üç farklı intrastromal vankomisin dozlarını kendi aralarında hem de kontrol grubuyla karşılaştırılarak değerlendirilmiştir. iii Korneanın morfolojik inceleme sonuçları şu şekildedir; tedavi öncesi ve sonrası toplam klinik skorlar, dört farklı grup için ayrı ayrı değerlendirildiğinde; kontrol grubunun (tedavisiz grup) 48.saat toplam klinik skoru, 24.saat skoruna kıyasla, anlamlı şekilde artış göstermektedir. Üç farklı tedavi grubunda ise tedavi sonrası toplam skor, tedavi öncesi toplam skorla karşılaştırılıp incelendiğinde sonuçlar şu şekildedir; 1) 0,5 mg/0,1 mL intrastromal vankomisin tedavi grubu ile 1 mg/0,1 mL intrastromal vankomisin grubunda anlamlı fark saptanmamıştır. 2) 2 mg/0,1 mL intrastromal vankomisin tedavi grubunda ise 48.saat toplam klinik skoru, 24.saat toplam klinik skora göre anlamlı olarak artış göstermiştir fakat bu sonuçların 24. ve 48. saat bulguları yani erken dönem bulguları olduğu unutulmamalıdır. Bunlara ek olarak, üç farklı tedavi dozunun, konjonktiva, kornea, iris ve ön kamara üzerindeki güvenliliğini sorgulamak için, yukarıda bahsedilen sekiz farklı parametreyi üç farklı tedavi grubu arasında ayrı ayrı değerlendirdik. Anlamlı sonuç şu şekildedir: 0,5 mg/0,1 mL, 1 mg/0,1 mL olmak üzere iki farklı intrastromal vankomisin dozu; iritis, ön kamarada fibrin, korneal ödeme neden olmazken, 2 mg/0,1 mL intrastromal vankomisin dozu, iritis, ön kamarada fibrin, korneal ödem gibi durumlara diğer iki doza kıyasla anlamlı olarak daha fazla neden olmuştur. Burada vurgulamak istediğimiz nokta şudur ki; vankomisin etken maddesinin halihazırda korneal epitel, endotel hücrelerine ve ön kamarada fibrin, iritis gibi yan etkileri bilinmektedir. 2 mg/0,1 mL intrastromal vankomisin dozu, bakteriyel yükü azaltması istatistiksel olarak anlamlı olsa da, korneal yan etkiler ortaya çıkardığı gösterilmiştir. Sonuç olarak, tek doz 0,5 mg/0,1 mL intrastromal vankomisin, tek doz 1 mg/0,1mL intrastromal vankomisin ve tek doz 2 mg/0,1 mL intrastromal vankomisin olmak üzere bu üç farklı tedavi dozu, kontrol keratit grubuna kıyasla bakteriyel yükü anlamlı şekilde azalttığı ve tedavi edici gücü ortaya konulmuştur. Fakat korneaya olası yan etki açısından değerlendirildiğinde, tek doz 0,5 mg/0,1 mL intrastromal vankomisin ve tek doz 1 mg/0,1 mL intrastromal vankomisin uygulamalarının; tek doz 2 mg/0,1 mL vankomisin uygulamasına kıyasla istatistiksel olarak daha güvenli olduğu ortaya konulmuştur. iv Bu çalışmayla, 0,5 mg/0,1 mL intrastromal vankomisin dozunun, 1 mg/0,1 mL vankomisine kıyasla daha az kimyasal etken madde ile istatistiksel olarak aynı etkinlik ve güvenlilik sağlanmasıyla, gelecek tedavilerde 0,5 mg/0,1 mL intrastromal vankomisin dozunun kullanılmasının daha uygun olduğunu düşünmekteyiz. Bu çalışma, MRSA etkenli bakteriyel keratit tedavisinde, korneal intrastromal vankomisin etkin dozaj karşılaştırma çalışması literatürdeki ilk deneysel çalışmadır. Mevcut kısıtlılıkları ile birlikte korneal intrastromal uygulama metodunun etkinlik ve güvenlik seviyelerinin gelecekte insan çalışmaları ile desteklenmesine ihtiyaç vardır.
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    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, Abdullah
    Purpose: 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.