Browsing by Author "Güler, C"

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    Lucas Polynomial Approach for System of High-Order Linear Differential Equations and Residual Error Estimation
    Çetin, M; Sezer, M; Güler, C
    An approximation method based on Lucas polynomials is presented for the solution of the system of high-order linear differential equations with variable coefficients under the mixed conditions. This method transforms the system of ordinary differential equations (ODEs) to the linear algebraic equations system by expanding the approximate solutions in terms of the Lucas polynomials with unknown coefficients and by using the matrix operations and collocation points. In addition, the error analysis based on residual function is developed for present method. To demonstrate the efficiency and accuracy of the method, numerical examples are given with the help of computer programmes written in Maple and Matlab.
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    Laguerre Collocation Method for Solving Fredholm Integro-Differential Equations with Functional Arguments
    Gürbüz, B; Sezer, M; Güler, C
    Laguerre collocation method is applied for solving a class of the Fredholm integro-differential equations with functional arguments. This method transforms the considered problem to a matrix equation which corresponds to a system of linear algebraic equations. The reliability and efficiency of the proposed scheme are demonstrated by some numerical experiments. Also, the approximate solutions are corrected by using the residual correction method.
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    Ocular findings in a measles epidemic among young adults
    Kayikçioglu, Ö; Kir, E; Söyler, M; Güler, C; Irkeç, M
    Purpose: To present ocular findings in a measles epidemic outbreak among young adults. Methods: Ophthalmic lesions in an unselected group of 61 young military personnel with measles were followed. Eighteen of the patients had symmetric keratitis in both eyes. They were treated with diclofenac sodium eyedrops qid in the right eye, while the left eye was observed untreated. The disappearance of the corneal lesions in both eyes was compared. Results: Forty patients (65.6%) had measles conjunctivitis with bulbar and tarsal conjunctival hyperemia. Five (8.2%) had increased mucous secretion. Thirty-five (57.4%) had superficial punctate corneal epithelial and subepithelial lesions which stained with fluorescein. Ten patients had corneal lesions without evident conjunctival pathology. Fourteen patients had subconjunctival hemorrhages, 12 of whom had bilateral lesions mostly in the superonasal quadrant. The time to disappearance of corneal lesions was 4.5 +/- 3.2 days in the diclophenac-treated right eyes, and 4.1 +/- 3.8 days in the left eyes. We did not observe a significant difference in the healing time between the two eyes (p = 0.75). Conclusion: Measles did not cause major ocular complications in healthy patients. Keratitis was unresponsive to diclophenac sodium eyedrops with respect to healing time and end result.
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    Religious fasting and intraocular pressure
    Kayikçioglu, Ö; Güler, C
    Purpose: To determine the effects of Islamic religious fasting on intraocular pressure. Methods: The authors measured diurnal intraocular pressure values during religious fasting and 1 month later in 38 healthy male volunteers with a mean age of 22.4 +/- 2.7 years. Body weight and urine specific gravity were determined to assess the extent of dehydration caused by fasting. Results: Although each patient had weight loss (0.1-1.4 kg) representing a slight dehydration caused by fasting, intraocular pressure values were not statistically different between fasting and nonfasting periods (P > 0.05). Conclusion: Fasting did not alter diurnal intraocular pressure values in healthy people.
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    Effects of betaxolol and latanoprost on ocular blood flow and visual fields in patients with primary open-angle glaucoma
    Erkin, EF; Tarhan, S; Kayikçioglu, ÖR; Deveci, H; Güler, C; Göktan, C
    PURPOSE. To evaluate the effects of betaxolol and latanoprost on ocular blood flow and visual fields in patients with primary open-angle glaucoma (POAG) by means of an observer-masked, prospective clinical study. METHODS. Thirty-two patients with newly diagnosed POAG were included in the study. The patients were randomized into two groups. The first group was treated with betaxolol 0.50% twice daily and the second group with latanoprost 0.005% once daily. Baseline and posttreatment examinations on the first and third months of treatment included intraocularpressure (IOP) measurement, automated visual field testing, and ocular blood flow assessment. For evaluation of visual fields, mean defect and pattern standard deviation indices were used. Ocular blood flow was assessed by means of color Doppler imaging of the central retinal artery (CRA) and the temporal short posterior ciliary artery (PCA). For each vessel, peak systolic (PSV) and end-diastolic (EDV) blood flow velocities were measured and resistivity index (RI) calculated. RESULTS. After exclusion of one noncompliant patient, the study was completed with 31 eyes of 31 patients. Both drugs significantly reduced IOP (p<0.05). The mean IOP lowering effect of latanoprost was significantly higher than that of betaxolol (p=0.03). Visual field indices exhibited no significant changes in either group (p>0.05). There were no significant changes in PSV or EDV measurements of CRA or PCA in either group (p>0.05). RI decreased in both CRA and PCA with both drugs. The mean changes between baseline and 3 month blood flow measurements were not significantly different between betaxolol and latanoprost (p>0.05). CONCLUSIONS. Over a treatment period of 3 months, both betaxolol and latanoprost tended to improve ocular blood flow without one of them being superior to the other The results suggest that the direct (non IOP-dependent)influence on ocular circulation is better for betaxolol than for latanoprost. In addition, neither drug caused significant generalized improvements in visual fields during this period.
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    Quality of Life Instruments Used in Ophthalmology and the Turkish Translation of National Eye Institute Visual Functioning Questionnaire (NEI-VFQ 25)
    Toprak, AB; Eser, E; Güler, C
    To investigate the relationship between ophthalmology and the Health Related Quality of Life (HRQOL) concept. To present a general knowledge about the HRQOL instruments used in ophthalmology and to give a detailed information about the National Eye Institute Visual Function Questionnaire (NEI-VFQ). We also aimed to present the translation process of NEI-VFQ into Turkish. Material and Methods: NEI-VFQ is a vision targeted HRQL questionnaire developed to assess the quality of life of patients with chronic eye disease. This instrument has been translated to Turkish by an established methodology. During the translation process validity and reliability tests were performed on a sample of 61 patients consisting of cataract, glaucoma, diabetic retinopathy, age related macular degeneration (ARMD), and degenerative myopia. Medline database from 1966 to the present using the following keywords and phrases: vision impairment, visual (or vision) disability, quality of life, functional assessment, questionnaire, and visual function. Results: The Turkish version of the NEI-VFQ had a high reliability and validity. The Cronbach alpha of the questionnaire was 0.97. The instrument had the sensitivity to discriminate patients according to disease severity, There were significant correlations between the World Health Organization Quality of Life Questionnaire (WHO-QOL) in the similar domains. Conclusion: The Turkish version of the NE-VFQ has the similar psychometric properties, reliability and validity as the original version. It can be used as an instrument to assess the effect of different therapeutic options and the effect of eye diseases to the quality of patients' lives.
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    Fluorescein dye disappearance test in patients with different degrees of epiphora
    Toprak, AB; Erkin, EF; Kayikçioglu, Ö; Seymenoglu, G; Güler, C; Unlu, HH
    PURPOSE. To assess the diagnostic efficacy of a modification of the fluorescein dye disappearance test (DDT) in patients with different degrees of epiphora. METHODS. DDT was performed by instilling a drop of 2% fluorescein in the eye. Schirmer tear test strips were placed in the lower conjunctival fornix, after 3 and 10 minutes. The colour dilution on the strips was compared to a scale with known standards and the most closely comparable colour dilution was chosen and recorded as the visual scale test (VST) grade of the strip. The grey-scale value (GV) of each strip was calculated by computer image analysis. The control group comprised 44 patients, mean age 44.8 years (SD 7.5, range 30-60). There were 13 patients in group 1 with moderate epiphora; mean age was 44.2 years (SD 9.5, range 30-60). There were 17 patients in group 2 with severe epiphora; mean age was 48.3 years (SD 7.7, range 37-60). RESULTS. VST and GV differed significantly between controls and group 1 patients at 3 minutes (p=0.002, p=0.001), and between controls and group 2 patients at 3 minutes (p<0.001, p<0.001). There was no difference between groups 1 and 2 patients in VST and GV at 3 minutes. The differences were highly significant between controls and group 1 at 10 minutes (p=0.001, p=0.007), and between controls and group 2 at 10 minutes (p<0.001, p<0.001). The differences in GV and VST between groups 1 and 2 were significant at 10 minutes (p=0.026, p=0.018). CONCLUSIONS. This modified DDT permits identification of different degrees of epiphora in a non-invasive manner, it can therefore be used to evaluate the outcome of different treatment strategies.
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    MRI Findings of Globe and Optic Nerves in Tilted Disk Syndrome
    Orguc, S; Toprak, AB; Demiray, B; Tarhan, S; Güler, C
    We assessed the anatomical variations of the globe and optic nerve in tilted disk (TD) syndrome using magnetic resonance imaging (MRI) findings and compared them with a control group. Eleven patients diagnosed with TD syndrome during eye examination were referred for MRI of the sella and chiasm to exclude intracranial mass lesions. The shape of the globe, the chiasmal angle, the insertion angles of the optic nerve in axial and parasagittal planes determined by lines parallel to the optic nerve and tangent to the globe in TD syndrome were compared with a control group consisting of 53 cases. Gender ratios were 7/4 (F/M) for the TD group and 35/18 for the control group (p>0.05). The insertion angle of the optic disk to the globe was wider in the temporal quadrant (p<0.05) and narrower in the nasal quadrant (p<0.05) in TD syndrome than in the control group. There was no significant difference in the superior and inferior insertion angles between the groups. The anterior-posterior (AP) diameter of the globe was significantly longer in patients with TD (p<0.05). There was no significant difference between the optic chiasm angles. The relationships of the optic disk and the globe were significantly different in patients with TD syndrome in comparison to the control group. TD syndrome is related to the malalignment of optic nerve and globe in the horizontal plane.
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    Prevention of posterior capsule opacification by retinoic acid and mitomycin
    Inan, ÜÜ; Öztürk, F; Kaynak, S; Ilker, SS; Özer, E; Güler, C
    Background: Our aim was to evaluate the effect of an intraoperative single dose of retinoic acid (RA) or mitomycin C (MMC) in preventing posterior capsule opacification (PCO). Methods: Twenty-seven rabbits were divided randomly into three groups. RA (250 mug/ml) and MMC (0.04 mg/ml) were given 0.1 ml by hydrosection and 0.9 ml into the capsular bag after phacoemulsification. The third group served as a control group. Three months after intervention PCO was graded clinically. Furthermore, proliferation of lens epithelial cells was evaluated histologically. Results: Two eyes developed corneal edema in the MMC group. On clinical assessment, RA and MMC were significantly effective in preventing PCO compared with controls (P <0.005). On histological analysis, there was significantly reduced proliferative activity on posterior capsules in the treatment groups, in contrast to multilayer cells in the control group. Conclusion: Intraoperative single-dose administration of RA and MMC significantly prevented the development of PCO in rabbit eyes. The optimal biocompatible dosage must be carefully determined by further investigation.
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    Prevention of posterior capsule opacification by intraoperative single-dose pharmacologic agents
    Inan, ÜÜ; Özturk, F; Kaynak, S; Kurt, E; Emiroglu, L; Özer, E; Ilker, SS; Güler, C
    Purpose. To determine whether an intraoperative single dose of dexamethasone, diclofenac, ethylenediaminetetraacetic acid (EDTA), a combination of EDTA and RGD peptide (arginine-glycin-aspartic acid sequence), or mitomycin-C (MMC) is a pharmacological means of preventing or reducing the development of posterior capsule opacification (PCO). Setting. Department of Ophthalmology, Celal Bayar University, School of Medicine, Manisa, and Department of Pathology, Dokur Eylul University, School of Medicine, izmir, Turkey. Methods: Fifty-four rabbits were randomly divided into 6 groups. Dexamethasone (4 mg/cc), diclofenac (2.5 mg/cc), EDTA (8 mg/cc), a combination of EDTA and RGD peptide (2.5 mg/cc), or MMC (0.04 mg/cc) was given, 0.1 cc by hydrodissection and 0.9 cc into the capsular bag after phacoemulsification. The sixth group served as a control group. After 3 months, the PCO was graded clinically and the proliferation of lens epithelial cells (LECs) was evaluated histologically. Results: The drugs were significantly effective in preventing PCO compared with the control (P < .005). Dexamethasone had a weaker effect than the other drugs. In histological analysis, although monolayer LECs in the dexamethasone and diclofenac groups were observed, there was no proliferative activity on the posterior capsules in the EDTA, EDTA+RGD, and MMC groups in contrast to the multilayer cells in the control. Conclusions: Intraoperative single-dose application of EDTA, EDTA+RGD peptide combination, and MMC significantly prevented the development of PCO in rabbit eyes. Diclofenac was less effective but also reduced PCO. Although dexamethasone did not prevent the proliferation of LECs, it decreased PCO clinically. (C) 2001 ASCRS and ESCRS.