Background and Objectives: Radial keratotomy is one of the current techniques in correction of myopia which has high prevalence in general population. The main purpose of this study was to evaluate changes in pattern and profile of corneal TOPOGRAPHY before, one week and third months after surgery. Secondary aims of this study were to record the subjective complaints and their correlation with topographic changes after surgery. Materials and Methods: In a clinical trial, comparison of corneal TOPOGRAPHY before and after RK was done in 50 eyes of 26 patients from 19/3/1997 to 20/9/2001. In all patients, routine eye examinations were performed before surgery along with determination of pattern and profile of corneal topographies (asphericity coefficient). Surgery were done under topical anesthesia with 0.2 mm diamond knife. Incision technique was as the American method with present standard nomograms. Corneal TOPOGRAPHY in first week and third months after surgery was done with special attention to central optical zone (COZ) pattern, presence of multifocality and asphericity coefficient. Patient’s complaints also were recorded.Results: The mean age of patients was 29 (18-60) years. 74% out of patients were male and 26% female. The mean duration of follow up was 10.5 months. The most common patterns of TOPOGRAPHY before surgery were asymmetric bow-tie (44%), symmetric bow-tie (40%), and spheric (8%). Corneal profile was prolate in 92% and spheric in 8% of cases. No case of oblate profile was found before surgery. Prevalent corneal patterns after surgery were regular polygonal (circular or elliptic) in 50% , Band like in 22%, and split in 28% of cases. Corneal multifocality was found in 38% of cases after surgery. Corneal profile was oblate in 94% and prolate in 6% of cases.Conclusion: Radial keratotomy induces various changes in corneal pattern and profile after surgery. Increased corneal asphericity and switching from prolate to oblate profile were noted. Multifocality in central flat zone can increase uncorrected visual acuity without considerable optical complications. Split pattern of central optic zone can cause diurnal fluctuation of vision.

Purpose: To evaluate quantitative topographic parameters of the cornea and to define topographic cone patterns and pachymetry in a series of keratoconus patients.Methods: We prospectively evaluated topographic findings of 130 eyes of 73 patients using Orbscan corneal TOPOGRAPHY system. The location, anterior and posterior surface elevation, curvature, amount of astigmatism and pachymetry were analyzed with special reference to the central point of corneal, the apex and the thinnest point.Results: The mean age of patients was 27/31 years ± 9.30 (SD). Fifty seven patients (67.6%) had bilaterial and sixteen (12.3%) had unilateral keratoconus.Most cones (64.6%) were located in the inferior temporal quadrant. 32.3% of cones were restricted to the central cornea and 4 were above horizontal meridian. Maximum apex elevation was 68.9D. The mean elevation of the apex was (0.195±0.055) mm. The mean distance between the apex and central point was (0.697±327) mm.The mean thickest of thinnest point of cornea was 398pm (range 143-551pm).Conclusion: Orbscan can provide accurate and subtle information about the shape and thickness of keratoconus which can help for early diagnosis of this disease.Orbscan TOPOGRAPHY system may be helpful in identifying patients who are potentially at risk for developing ectasia after lasik.

Purpose: To compare the visual outcome between wavefront-optimized (WFO) and TOPOGRAPHY-guided customized ablation (T-CAT) for compound myopic astigmatism.Methods: This double blind, prospective clinical trial study comprised 40 eyes (21 patients) with compound myopic astigmatism. Myopia was considered between 1 to 8 diopters and astigmatism was considered between 1 to 3 diopters. Patients were randomly divided into two groups: 1) the wavefront optimized group and 2) the TOPOGRAPHY-guided group. All surgeries were done with Allegretto WaveLight® EX500laser eximer. Visual acuity, refractive error, corneal aberrations, ocular high order aberrations and corneal asphericity were measured before and 6 months after surgery. The results were compared between the two groups.Results: Six months after surgery, the best corrected visual acuity was similar in two groups. Mean spherical equivalent refraction was -4.33 ± 1.7D and -4.13 ± 1.61 D (P=0.528) to -0.06 ± 0.14 D and -0.04 ± 0.09D (P=0.586) in wavefront optimized and TOPOGRAPHY-guided groups after surgery. Less stromal tissue was ablated in the TOPOGRAPHY-guided group than in the wavefront optimized group (P=0.969). There was no significant difference between the 3rd and 4th grade corneal aberrations between the two groups before and after the surgery (P>0.05). Corneal spherical aberration was increased in both groups. This increase was higher in the WFO group (P=0.798). Higher order aberrations increased from 0.35 ± 0.14 m and 0.35 ± 0.11 m (P=0.496) to 0.52 ± 0.15m and 0.49 ± 0.16 m (P=0.786) in the WFO and T-CAT groups, respectively. Corneal asphericity increased in group two, which was higher in the WFO group (P=0.679).Conclusion: The results of TOPOGRAPHY-guided and wavefront optimized treatments with Allegretto eximer laser were similar in the correction of compound myopic astigmatism, but TCAT induced fewer HOAs.

Introduction: TOPOGRAPHY is an important and effective property affecting the soil quality. Some researchers demonstrated that degree and aspect of land slope may influence the particle size distribution and gravel. Slope degree affects the surface and subsurface run-off, drainage, soil temperature, stability of soil aggregates and soil erosion. This research was carried out to determine the spatial variation of soil properties in different slope degrees of northern and southern slopes in Khorasan Razavei province, Iran.Material and Methods: This study was performed in Sanganeh research station (longitude 60o 15ʹ60ʺ and latitude 36o 41ʹ 36ʺ), of north-eastern, Khorasan Razavi province of Iran. In order to study the effects of TOPOGRAPHY on some soil physical and chemical properties, a topo-sequence with the same slope length, parent materials and cover crops was selected.30 soil samples (0-30 cm depth) were collected from different slopes of less than 5, 5-15, 15-30, 30-50 and more than 50 percent of both southern and northern aspects. In this study, the soil particle size distribution (texture) was measured by hydrometer method, organic carbon and calcium carbonate were determined by wet oxidation and titration with HCl 6 M, respectively and soil structural stability index, aggregates mean weight diameter and particles fractal dimension were calculated by related equations. Finally, the studied soil properties of 5 slopes (less than 5, 5-15, 15-30, 30-50, and more than 50%) and 2 aspects (north and south) with 3 replicates were compared by nested experimental design and Tuky test in JMP statistical software.Results and Discussion: The maximum and minimum clay contents as well as fractal dimension and organic carbon contents were found in less than 5% and more than 50% of south slopes, respectively. Clay content and fractal dimension in north aspect were also significantly (P<0.001) more than south one. In reverse, the sand content in south aspect was significantly (P<0.05) more than north one. There was no significant difference between silt content in north and south aspects, but the silt content was maximum value in toe slope, which reflects the transportation of silt due to soil erosion from steeper parts of slope to toe slope. The differences of calcium carbonate and organic matter contents in different slope degrees were significant (P<0.05). The minimum and maximum calcium carbonate contents were noted in less than 5% and more than 50% of south slopes, respectively and the average of calcium carbonate in south aspect was significantly (P<0.001) more than the north one, while the organic carbon contents in north aspect was significantly (P<0.001) more than the south one. In both southern and northern slopes, the OC as a result of high radiation and less soil moisture content and then poor crop cover has been decreased by increasing the slope degree. The highest and least values of MWD in studied area were found in less than 5% and 30-50% degree of south slope, respectively and the average of MWD in north aspect was significantly (P<0.01) more than south slope, too. The value of structural stability index in north aspect also was more than the south one and it was decreased by increasing the slope degree.Conclusion: The results showed that, in spite of the same soil texture class in different slope degrees of both north and south aspects, particle size distribution in different parts of slope was varied. By decreasing the degree of slope, the fractal dimension of solid particles increased and vice versa. It seems that the fractal dimension of solid particles and structural stability index of soil can be replaced by soil texture and MWD, respectively, because they can represent the best and explicit description of particle size distribution and the effect of soil forming process in sloped regions, and soil structure.

Background: Hemorrhagic Brain Infarction (HBI) is an important finding which has been reported mainly in cardioembolic strokes. Although clinical status of the patients is not often deteriorated, however decision making for anticoagulation's difficult in HBI patients.Materials and Methods: This descriptive-cross sectional study, was carried out in 100 consecutive patients with HBI admitted in Valie Asr Hospital, Khorasan during 2003-2004. HBI was diagnosed by CT scan within 24-48 hours of stroke onset and the arterial territory of the infarct was confirmed by topographic maps of brain in CT. Clinical status of the patients was evaluated each 12 hours during hospitalization, period. Etiologic work up of our stroke patients included routine blood chemistry and hematologic tests, ECG, transthoracic echocardiography and carotid duplex and transcranial Doppler sonography.Results: 54 females and 46 males with mean age 62.3 had HBI. 88% of the HBI occurred within MCA territory. The lenticulostriate artery was involved alone in 46% and with other MCA branches in 23% of cases. In patients with HBI, clinical status was deteriorated in 16%, recovered in 38% and stabilized in 46%, during hospitalization period respectively.The cardio embolism consisted 40% of etiologies in our HBI patients.Conclusion: Cardioembolism was not the main etiology in our patients with HBI. This finding reduces generality of the Fisher-Adams hypothesis. HBI infrequently leads to clinical deterioration of the patients.

The subject of radiation damage in silicon by plasma and electron beam technique has been investigated for many years. Modification for having particular surface TOPOGRAPHY is also sometimes desired specially in those experiments that ion interaction with surface is very sensitive to the surface TOPOGRAPHY. In our previous work in order to study the electron bombardment effect on silicon, we used our new design electron source. In this paper, silicon samples were bombarded by 30 keV argon ions on normal to the surface with doses in the 1×1016-2×1017 Ar+/cm2 range. Topographical changes induced on silicon surface, generation of blisters and evolution of them at different doses observed by atomic force microscopy. Measurement of mean surface height show that for doses greater than 1×1017 Ar+/cm2 the height decreases because of sputtering. The optical properties of samples after Ar+ irradiation measured by a UV-Vis-NIR spectrophotometer.

Objective: Topographical parameters are important to guide stem cell behaviour, including geometry, size, lateral spacing and surface chemistry, which have been reported to affect the adhesion, growth, proliferation, and differentiation of stem cells. Nanostuctures on biomaterials provides a useful tool for guiding diferentiation, as the features are more durable than surface chemistry and can be modified in size and shape to suit the desired application. The underlying mechanism of how TOPOGRAPHY influences stem cells remains unknown. Nevertheless, the advance of nanotechnology has enabled the fabrication of synthetic topographies with different materials, shapes and sizes, allowing systematic studies of the underlying mechanism. Here we demonstrate the importance of nanoscale surface TOPOGRAPHY as a crucial factor to control adhesion and differentiation of TERA 2 embryonic stem cells. Since orientation and symmetry may also be important, we have examined how the geometry of arrangement of zinc oxide nanotubes on a substratum affects the differentiation of stem cells growing on them under simulated in vitro conditions.Materials and Methods: TERA 2 stem cells re-enhanced from -80°C to 37°C in culture flask.Results: The results clearly show that these architectures caused differential guidance for the filopodia (extensions) of stem cells. Cells adhered far less to vertical ZnO nanorods than to horizontal ZnO. The few cells that adhered to vertical ZnO nanorods were rounded and not viable compared to horizontal ZnO. Cells that initially adhered to the vertical nanorods were unable to spread. This suggests that it is the lack of initial attachment and spreading that causes premature cell death.Conclusion: The ZnO nanorods are useful to affect the behavior of stem cells and, potentially their differentiation. Altering the orientation of nanotubular zinc oxide on the surface revealed changes in stem cell behaviour, offering a promising nanotechnology-based route for directed tissue engineering with excellent controllable mechanical properties.

Background: Etiologic overlaps may occur in patients with ischemic stroke depending on the diagnostic investigations and classification criteria. Methods: Consecutive ischemic stroke patients admitted in Mackenzie hospital, Canada from August 2003 to August 2004 underwent a standard battery of diagnostic investigations by stroke neurologists. Stroke mechanism was defined based on the Toast criteria. Stroke TOPOGRAPHY subtypes were small and large artery territory infarcts. Results: A total of 302 stroke patients (159 female, 143 male) were registered. Small and large artery territory infarcts consisted 25.5% and 74.5% of our TOPOGRAPHY respectively. Etiologic overlaps were found in 17.5% of the patients. Cardiac source of embolism was significantly more frequent in patients with large artery territory infarcts (p= 0.002) but frequency difference of corresponing large artery atherosclerotic stenosis was not significant in these topographies (p= 0.378). Etiologic overlaps were more frequent in patients with small artery territory infarcts (p= 0.004). Conclusion: Etiologic overlaps are frequent and should be considered for optimal management of the ischemic stroke patients.