Mesut Erdurmus

Antioxidant Status and Oxidative Stress in Primary Open Angle Glaucoma and Pseudoexfoliative Glaucoma

Purpose: The aim of this study was to establish the antioxidant status and oxidative stress in patients with primary open-angle glaucoma (POAG) and pseudoexfoliative glaucoma (PEG). Methods: Serum levels of total antioxidant capacity (TAC) and superoxide dismutase (SOD) as indicators of antioxidant status; and total oxidant status (TOS), nitric oxide (NO), protein carbonyl (PC), and malondialdehyde (MDA) as indicators of oxidative stress were measured from the blood samples of patients with POAG (n = 23), PEG (n = 24) and healthy control subjects (n = 19) by spectrophotometry. Results: Mean TAC level was 0.6 ± 0.1 mmol/L in the POAG group; 0.5 ± 0.1 mmol/L in the PEG group and 1.2 ± 0.3 mmol/L in the control group (p = 0.001). Mean SOD level was 13 ± 0.5 mg/L in the POAG group, 11.6 ± 0.2 mg/L in the PEG group and 9.4 ± 0.6 mg/L in the control group (p = 0.001). Mean TOS level was 19.6 ± 2.6 μmol/L in the POAG group, 21.2 ± 4.2 μmol/L in the PEG group and 15.1 ± 7 μmol/L in the control group (p = 0.001). Mean NO level was 74.3 ± 14.4 µmol/L in the POAG group, 66.1 ± 8.1 µmol/L in the PEG group and 62.3 ± 13.5 µmol/L in the control group (p = 0.005). Mean PC level was 641.5 ± 102.5 nmol/mg in the POAG group, 988.3 ± 214.7 nmol/mg in the PEG group and 654.4 ± 150.7 nmol/mg in the control group (p = 0.001). Mean MDA level was 1.9 ± 0.2 µmol/L in the POAG group, 1.7 ± 0.4 µmol/L in the PEG group and 1.1 ± 0.2 µmol/L in the control group (p = 0.001). Conclusion: The findings of the present study are potentially of significance and add to the growing body of evidence for oxidative stress in POAG and PEG. Decreased antioxidant defense and increased oxidative stress system may play an important role in the pathogenesis of POAG and PEG.

In vitro susceptibility patterns of methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus corneal isolates to antibiotics.

Purpose: To determine the in vitro susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MRCNS) isolates to various antibiotics. Methods: All cases of bacterial keratitis caused by Staphylococcus species during 2006 and 2007 were identified. The isolates were divided according to species and susceptibility to methicillin into 4 groups: methicillin-susceptible S. aureus, methicillin-susceptible coagulase-negative Staphylococcus, MRSA, and MRCNS. Routine susceptibility testing for Staphylococcus species to methicillin and 19 other antibiotics was performed using the MicroScan POS Breakpoint Combo Panel Type 20. Results: One hundred fifty-seven isolates were identified. Forty isolates were S. aureus, including 21 MRSA, and 117 isolates were coagulase-negative Staphylococcus, including 29 MRCNS. All MRSA isolates were susceptible to gentamicin, linezolid, rifampin, tetracycline, and vancomycin and were resistant to penicillin, cefazolin, cefepime, azithromycin, erythromycin, and ofloxacin. Ninety percent of MRSA isolates were resistant to fourth-generation fluoroquinolones. All MRCNS isolates were susceptible to vancomycin, chloramphenicol, linezolid, and rifampin and were resistant to penicillin, cefazolin, cefepime, and azithromycin. Sixty-five percent of the MRCNS isolates were susceptible to fourth-generation fluoroquinolones and gentamicin. Conclusions: All MRSA and MRCNS isolates were sensitive to vancomycin, linezolid, and rifampin. MRSA isolates were generally sensitive to gentamicin and tetracycline and resistant to fourth-generation fluoroquinolones. MRCNS isolates were not consistently sensitive to gentamicin, tetracycline, or fourth-generation fluoroquinolones.

Contact Lens Related Quality of Life in Patients With Keratoconus

Objectives: To assess the impact of the different types of contact lenses (CLs) on quality of life (QoL) in patients with keratoconus based on self-reported results from The Contact Lens Impact on Quality of Life (CLIQ) Questionnaire. Methods: Consecutive keratoconus patients who wore CLs (rigid gas permeable [RGP], hybrid or soft toric) at least in one eye were asked to complete the CLIQ questionnaire on the Cornea Service, Wills Eye Institute. Results: A total of 71 patients with a mean age of 42.6 ± 13.1 year were included in the study. One eye of each patient was included in the study. Of these, 40 eyes used rigid gas-permeable lenses, 20 eyes used hybrid lenses and 11 eyes used soft toric lenses. The mean CLIQperson measure was 45.5 ± 8.2 in RGP group, 45.4 ± 7.5 in hybrid group and 48.4 ± 10.5 in soft toric group. There was no significant difference among the three groups in self-reported results from the CLIQ questionnaire (P = 0.8). Conclusions: Subjects with keratoconus who wear RGP, hybrid or soft toric CLs, reported similar contact lens impact on their QoL.

Inhibitory effects of regorafenib, a multiple tyrosine kinase inhibitor, on corneal neovascularization.

AIM To evaluate the inhibitory effects of regorafenib (BAY 73-4506), a multikinase inhibitor, on corneal neovascularization (NV). METHODS Thirty adult male Sprague-Dawley rats weighing 250-300 g, were used. Corneal NV was induced by NaOH in the left eyes of each rat. Following the establishment of alkali burn, the animals were randomized into five groups according to topical treatment. Group 1 (n = 6) received 0.9% NaCl, Group 2 (n = 6) received dimethyl sulfoxide, Group 3 (n = 6) received regorafenib 1 mg/mL, Group 4 (n =6) received bevacizumab 5 mg/mL and Group 5 (n = 6) received 0.1% dexamethasone phosphate. On the 7d, the corneal surface covered with neovascular vessels was measured on photographs as the percentage of the corneas total area using computer-imaging analysis. The corneas obtained from rats were semiquantitatively evaluated for caspase-3 and vascular endothelial growth factor by immunostaining. RESULTS A statistically significant difference in the percent area of corneal NV was found among the groups (P <0.001). Although the Group 5 had the smallest percent area of corneal NV, there was no difference among Groups 3, 4 and 5 (P >0.005). There was a statistically significant difference among the groups in apoptotic cell density (P = 0.002). The staining intensity of vascular endothelial growth factor in the epithelial and endothelial layers of cornea was significantly different among the groups (P <0.05). The staining intensity of epithelial and endothelial vascular endothelial growth factor was significantly weaker in Groups 3, 4 and 5 than in Groups 1 and 2. CONCLUSION Topical administration of regorafenib 1 mg/mL is partly effective for preventing alkali-induced corneal NV in rats.

Aqueous humour and serum concentration of asymmetric dimethyl arginine in pseudoexfoliation syndrome

Objective Asymmetric dimethyl arginine (ADMA) is the major endogenous inhibitor of nitric oxide synthase. ADMA is related to endothelial dysfunction and is an independent cardiovascular risk factor. This study aimed to evaluate the concentration of ADMA in aqueous humour and serum samples of patients with pseudoexfoliation (PEX) syndrome. Materials and Methods 21 cataract patients with PEX syndrome (PEX group) and 18 cataract patients without PEX syndrome (control group) were enrolled in the study. ADMA was measured in the aqueous humour and serum of the PEX and control groups. ELISA was used to determine the ADMA concentration. Results Mean aqueous humour ADMA concentration in the PEX group was 0.39±0.07 μmol/l and in the control group was 0.34±0.06 μmol/l. Mean serum ADMA concentration in the PEX group was 0.56±0.21 μmol/l and in the control group was 0.44±0.12 μmol/l. ADMA concentration of aqueous humour in the PEX group was significantly higher than the control group (p=0.026). Similarly, ADMA concentration of serum in the PEX group was significantly higher than the control group (p=0.039). Conclusions The findings of the present study could suggest that ADMA might play a role in the aetiopathogenesis of PEX syndrome. Higher aqueous and serum levels of ADMA might be potential evidence of endothelial dysfunction in PEX syndrome.

Inhibitory Effects of SU5416, a Selective Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitor, on Experimental Corneal Neovascularization

Purpose: Treatment of neovascularization in ocular diseases with vascular endothelial growth factor (VEGF) inhibition shows promising results. SU5416 is a low-molecular-weight tyrosine kinase inhibitor. It selectively inhibits the membrane-bound tyrosine kinase activity of VEGF-2 receptor (Flk-1/KDR) and blocks the intracellular signaling process. The aim of this study was to evaluate the effect of SU5416 on corneal neovascularization. Methods: Corneas were cauterized with silver nitrate/potassium nitrate sticks in 20 eyes of 20 BALB/C mice. In the study group (n = 10), SU5416 (25 mg/kg) dissolved in dimethyl sulfoxide was given as an intraperitoneal injection in a single daily dose for 7 days. The other group of 10 mice given intraperitoneal dimethyl sulfoxide alone served as a control group. After 7 days, corneal neovascularization was evaluated using photographs captured by fluorescein angiography. Colored photographs were taken by a biomicroscope with a digital camera. Data were expressed as mean neovascular length and mean number of new vessels for each animal. The values were computed and compared between the groups. Results: The mean burn stimulus intensities were not different between the groups. In the study group, the mean length of the vessels and the mean number of vessels were 0.49 ± 0.05 and 11.20 ± 1.69 mm, respectively. In the control group, the mean length of the vessels and the mean number of the vessels were 0.89 ± 0.11 and 17.80 ± 1.03 mm, respectively. There is a statistically significant difference in the mean length and the mean number of new vessels between the study and control groups (p < 0.001). Conclusion: Selective inhibition of VEGFR-2 (Flk-1/KDR) tyrosine kinase with SU5416 was shown to have an inhibitory effect on corneal neovascularization in this animal model. VEGFR-2 (Flk-1/KDR) tyrosine kinase inhibition may represent a different pathway for treatment of the neovascularization process in ocular pathologies. Fluorescein angiography photographs of new vessels on the cornea may provide a better evaluation of neovascularization than colored images in animal models.

Cyclosporin effectively inhibits posterior capsule opacification after phacoemulsification in rabbits: a preliminary study

Purpose:  To evaluate whether cyclosporin A prevents or reduce posterior capsule opacification after phacoemulsification surgery in rabbit eyes.

Central corneal thickness in individuals with intellectual disabilities.

Purpose: To assess central corneal thickness (CCT) values in individuals with intellectual disabilities (ID). Methods: The study group was made up of 25 participants with ID (mean age, 36.9 ± 8.7 years). The control group was made up of 25 healthy individuals (mean age, 37.1 ± 10.1 years) with normal intellectual capacity and without any systemic or intraocular pathology. CCT value was measured by ultrasound pachymetry. Ten consecutive measurements were made at the center of the cornea of each eye. Results: In the ID group, mean CCT value was 554.0 ± 39.7 μm in the right eye and 556.8 ± 38.7 μm in the left eye. In the control group, mean CCT value was 535.7 ± 24.2 μm in the right eye and 536.5 ± 24.8 μm in the left eye. CCT value in the ID group was significantly greater than in the control group for both right (P < 0.05) and left eyes (P < 0.02). Conclusions: CCT should be kept in mind during measurements of intraocular pressure (IOP) in individuals with ID because their CCTs may be greater than those in the general population.

Amiodarone-induced keratopathy: full-thickness corneal involvement.

Purpose. To report a case of amiodarone-induced keratopathy involving the entire cornea, including the endothelium. Methods. Clinical case description and documentation with confocal laser scanning microscopy using the Heidelberg Retinal Tomography II (HRT II). Results. A 65 year-old man with a history of blurred vision and seeing halos around lights had been treated with amiodarone for 6 years. Best-corrected visual acuity was 20/25 in each eye. Slitlamp examination of both eyes showed a bilateral, symmetric, whorllike pattern of brown deposits in the inferocentral corneal epithelium. Diffuse and fine deposits resembling keratic precipitates in the central part of the endothelial face were also detected. Examination of the lens, optic nerve, and fundus in each eye did not show any abnormalities that could be attributed to the amiodarone therapy. Severe endothelial deposition was documented with the confocal laser scanning microscope of the HRT II. Conclusions. Amiodarone-induced keratopathy with confluent and diffuse endothelial deposition is rare, and it may be indicative of a more severe toxicity associated with amiodarone.

Serum Levels of Omentin in Pseudoexfoliation Syndrome.

Purpose:Omentin, a member of the adipocytokines family, is derived from adipose tissue and a lower level of serum omentin is considered as a metabolic risk factor. The aim of the present study is to evaluate the serum levels of omentin in patients with pseudoexfoliation syndrome (PES). Materials and Methods:Patients without any systemic or ocular disease other than PES were included in the study. Age-matched and sex-matched healthy volunteers without PES were accepted as a control group. After detailed ophthalmologic examination, blood samples were obtained from a forearm vein. Serum levels of omentin were determined by the method of enzyme-linked immunosorbent assay. Results:The mean age of the PES group (12 females, 12 males, n=24) was 75.2±8.4 years, and the control group (10 females, 10 males, n=20) was 75±6.7 years. There was no difference between the groups in terms of age (P=0.93) and sex (P=0.9). The mean serum levels of omentin in the PES group were 801.5±317.1 ng/mL and in the control group were 1150.1±584.1 ng/mL. The mean serum omentin levels were significantly lower in patients with PES (P=0.016). Conclusion:Lower levels of serum omentin in patients with PES compared with healthy subjects may support the theory of systemic nature of the disease.