الفهرس 
Introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
Two hundred normal orbits of 100 subjects (50 men and 50 women) were evaluated in the present study. The age range of the subjects was 20-60 years. They were referred to Radiology department, Minia University Hospital from June 2011 to July 2012 for CT of brain, orbit and paranasal sinuses. All subjects in the present study were free of clinical evidence or history of endocrine disease such as hyperthyroidism or any orbital disorder.
Axial, 2mm thick non-overlapping contiguous, sections were obtained in all subjects and reformatted coronal and sagittal scans with a CT scanner GE Bright speed 16 slices with detector collimation 0.75mm. Subjects were asked to maintain forward gaze and gentle eye closure during the scans to prevent asymmetric extraocular muscle contraction.
The globe position (GP) in CT was determined by measuring the perpendicular distance between the IZL and the posterior margin of the globe at the mid-globe section on axial scans. The width of the optic nerve-sheath complex was also measured perpendicular to its course in the axial, coronal and sagittal CT scans. The length of both anterior and posterior segments of the eye, both anteroposterior and bipolar diameters of the lens, the thickness of the sclera, optic canal width and length were measured on axial scans. The intraorbital length of the optic nerve was measured on sagittal scan. Horizontal diameters of the lateral rectus and medial rectus muscles were measured on both axial and coronal scans. Vertical diameters of the superior muscle group (superior rectus and levator palpebrae superioris) and the inferior rectus muscle were measured on both coronal and sagittal scans. Measurements were done directly on CD using dicom. In the present study, the diameter of each muscle was measured at its maximum.
Statistical analysis of data was conducted using SPSS computer statistical program version 16. The mean values ± standard deviation (SD), and correlation coeffecients were computed and presented in tables and graphs (histograms). Analysis of variance (ANOVA) was used to test for significant differences between the mean values of the various study variables in men and women for sexual differences. ANOVA was also used to detect side differences between the study variables of the right and left sides. The statistical significance level was chosen at P<0.05.
It was found that The IZL was significantly longer in men than in women. This denotes that the horizontal dimension of skull in men is longer than in women at orbital level. And this is in agreement with other studies that of Ozgen and Ariyurek (1998) Hudson et al., (1991) and Holt et al., (1985) Lee et al., (2001).
It was found that there is a significant side difference regarding globe position in men, scleral thickness, the optic nerve thickness on axial scan in men, the thickness of the lateral rectus muscle on coronal scan.
It was found that there is no significant side difference regarding globe position in women, anterior and posterior segments, optic canal width and length, AP and bipolar diameters of the lens, the optic nerve thickness on axial scan in women, the optic nerve thickness on coronal and sagittal scans, the intra orbital length of the optic nerve, the thickness of the superior group muscles on coronal scan, the thickness of the inferior rectus muscle on coronal scan, the thickness of the medial rectus muscle on coronal scan, the thickness of the superior group muscles muscle on sagittal scan, the thickness of the inferior rectus muscle on sagittal scan, the thickness of the medial rectus muscle on axial scan, the thickness of the lateral rectus muscle on axial scan.
It was found that there is a significant sexual difference regarding the globe position, anterior segment on the right side, posterior segment, the intra orbital length of the optic nerve, the thickness of the superior group muscles on sagittal scan on the right side.
It was found that there is no significant sexual difference regarding anterior segment on the left side, scleral thickness, optic canal width and length, AP and bipolar diameters of the lens, the optic nerve thickness on axial, coronal and sagittal scans, the thickness of the superior group muscles on coronal scan, the thickness of the inferior rectus muscle on coronal scan, the thickness of the medial rectus muscle on coronal scan, the thickness of the lateral rectus muscle on coronal scan, the thickness of the superior group muscles on sagittal scan on the left side, the thickness of the inferior rectus muscle on sagittal scan, the thickness of the medial rectus muscles on axial scan, the thickness of the lateral rectus muscle on axial scan.
Also it was found that the measurements of the present study were higher than that of Korean population this might be due to racial causes.