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Öğe Clearance of Intravitreal Daptomycin in Uveitis-Induced Rabbit Model(Taylor & Francis Inc, 2015) Ozcimen, Muammer; Sakarya, Yasar; Ozcimen, Serap; Sakarya, Rabia; Goktas, Sertan; Iyisoy, Sinan; Alpfidan, IsmailPurpose: To investigate the elimination rate of daptomycin after intravitreal injection in uveitis-induced rabbits. Materials and methods: Intravitreal injection of the single dose of 200 mu g/0.05mL daptomycin was administered to rabbits starting 24 h after induction of uveitis by an intravitreal endotoxin injection. Aqueous humor and vitreous humor samples of eight eyes per time point were collected at selected time intervals (1, 3, 6, 24, 48, 72 and 96 h), and the in vitreous half-life was calculated. Daptomycin concentrations in vitreous and aqueous humor were assayed with high-performance liquid chromatography. Results: The vitreous concentration was noted to decline slowly with time. The mean vitreous concentration was 23.25 +/- 10.99 mu g/mL and 11.10 +/- 3.33 mu g/mL at 96 h in inflamed and normal eyes, respectively. The vitreous daptomycin concentration showed an exponential decay with a half-life of 25.67 h in normal eyes and 34.6 h in inflamed eyes. The aqueous levels of daptomycin in normal eyes were low but remained significantly higher than those of inflamed eyes. Conclusions: Given that the injected dose corresponds to several times the minimum inhibitory concentrations of organisms most involved in endophthalmitis, and that therapeutic levels are present up to 96 h after injection, intravitreal daptomycin should be considered for the treatment of endophthalmitis caused by Gram-positive bacteria.Öğe Daptomycin versus Vancomycin in an Enterococcus faecalis Endophthalmitis Rabbit Model(Taylor & Francis Inc, 2016) Ozcimen, Muammer; Kurtoglu, Muhammet G.; Goktas, Sertan; Omeroglu, Ethem; Sakarya, Yasar; Alpfidan, Ismail; Ozcimen, SerapPurpose: To compare bactericidal activities of daptomycin (DAP) and vancomycin (VAN) in an experimental rabbit model of Enterococcus faecalis endophthalmitis. Materials and methods: The right vitreous cavities of 24 New Zealand rabbits were inoculated with 100 colony-forming units of E. faecalis; and after 24 h, rabbits were randomly divided into three groups. DAP group (n = 8, 0.2 mg/0.05 ml intravitreally), VAN group (n = 8, 1 mg/0.05 ml intravitreally) and balanced salt solution group (BSS, n = 8, 0.05 ml intravitreally). Clinical examination scores were recorded, and vitreous aspirates were obtained for microbiological analysis on days 0, 1, 2, 3 and 4. Rabbits were sacrificed, and the eyes were enucleated for histopathological assessment. Results: There was no difference between the DAP, VAN and BSS groups in terms of the clinical grading of endophthalmitis 24 h after the inoculation. The bacterial counts were similar between the VAN and DAP groups except on day 1, where it was significantly lower than those in the VAN group (p = 0.003). On day 4, 62% of the eyes treated with DAP, and 50% of the eyes treated with VAN were sterilized. All of the eyes from the BSS group showed increasing bacterial growth from day 0 to day 4. There was no difference between the DAP and VAN groups in terms of the histopathological and clinical examination scores, while they were significantly lower than those in the BSS group. Conclusions: This study demonstrates evidence of the effectiveness of DAP for the treatment of experimental E. faecalis endophthalmitis.Öğe The effect of rebreathing and hyperventilation on retinal and choroidal vessels measured by spectral domain optical coherence tomography(Taylor & Francis Ltd, 2015) Ozcimen, Muammer; Sakarya, Yasar; Goktas, Sertan; Sakarya, Rabia; Alpfidan, Ismail; Yener, Halil I.; Demir, Lutfi S.Objective: The purpose of this study was to examine the vasoreactivity in retina and choroid of the healthy eyes in response to experimentally altered partial arterial pressure of carbon dioxide (PaCO2) using a non-invasive technique, spectral domain optical coherence tomography (SD-OCT). Materials and methods: The study included non-smoking participants between 18 and 35 years of age, having visual acuity of 20/20 and with no systemic and ocular diseases. At baseline, the participants breathed room air (normocapnia). Hypocapnia was created with the help of hyperventilation; for this, the participants were instructed to draw deep and quick breaths, resulting one breathing cycle per 2 s. To create hypercapnia subjects rebreathed from a 5 l bag at least 3 min. Choroidal thickness and retinal artery diameter were measured at baseline, and hyperventilation and rebreathing conditions by SD-OCT. Results: Twenty eyes of 20 healthy subjects were included in this study. Their mean age was 24.90 +/- 5.32 years. Hyperventilation caused a significant reduction in choroidal thickness, compared with baseline, at all points; whereas rebreathing caused no significant change at all points. The mean diameters of the arteries were 151.80 +/- 7.88 mm, with a significant decline to 148.90 +/- 7.25 mm at hyperventilation condition and a significant increase to 153.50 +/- 7.88 mm at rebreathing condition (p = 0.018, p = 0.043, respectively). Conclusion: This study demonstrated that, SD-OCT was a useful tool in measuring the ocular vascular response under hypercapnia and hypocapnia conditions. These findings may be helpful for further understanding the physiological nature of ocular blood flow and this preliminary study provides a basis for future studies.Öğe Retinal Nerve Fiber Layer Thickness in Children With ADHD(Sage Publications Inc, 2018) Herguner, Arzu; Alpfidan, Ismail; Yar, Ahmet; Erdogan, Erkan; Metin, Ozge; Sakarya, Yasar; Herguner, SabriObjectives: The current study aims to compare retinal nerve fiber layer (RNFL) thickness, macular thickness, and macular volume between children with ADHD and a control group. Method: The study group included children with ADHD and the control group consisted of age- and gender-matched participants without any psychiatric disorder. In all participants, RNFL thickness, macular thickness, and macular volume were measured by using spectral domain-optical coherence tomography (SD-OCT). ADHD symptom severity was evaluated by using parent-report measures, including Conners' Parent Rating Scale-Revised: Short Form (CPRS-R: S) and the Strengths and Difficulties Questionnaire: Parent Form (SDQ: P). Results: We compared 90 eyes of 45 children with ADHD and 90 eyes of 45 controls. ADHD group had significantly lower RNFL thickness only in nasal quadrant than the controls. The remaining RNFL quadrants, macular thickness, and volume were not significantly different between groups. There was a reverse correlation between RNFL thickness and ADHD symptom severity. Conclusion: This is the first study examining the RNFL thickness in ADHD. Our findings showed that nasal RNFL thickness was lower, indicating reduced unmyelinated axons in the retina of children with ADHD. The results of this study support the evidence that ADHD involves a lag in cortical maturation and this is measurable in the retina.
