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Title: A study of orbit development and its relationship to eye size in myopia using magnetic resonance imaging
Authors: Chau, Cheuk-man Anson
Keywords: Hong Kong Polytechnic University -- Dissertations
Eye-sockets -- Imaging
Magnetic resonance imaging
Issue Date: 2003
Publisher: The Hong Kong Polytechnic University
Abstract: This study covers three aspects: the first is a calibration study performed on phantoms simulating the orbit and eyeball to evaluate the accuracy of volumetric determination using MRI DICOM (Digital Imaging and Communication in Medicine) images; the second is a study on the orbit development in Hong Kong Chinese and the third is a study to demonstrate the relationship between eye size and the volume of the orbit in adult subjects with varying degrees of myopia. Calibration was conducted using ten tailor-made spherical silicon balls ranging from 5 to 14 cm³ and 10 silicon moulds of orbits from 10 human dry skulls. These were used to simulate the eyes and orbits respectively. The phantoms were subjected to MRI scanning. A T2-weighted sequence was used. The volume of each phantom was computed and compared with the known physical volumes. The computed and physical volumes were highly correlated for both eyeball and the orbit phantoms. Coefficient of variations of the computed and physical volumes were low. Consequently, it is possible to apply a calibration value to the computed volume to estimate the physical volume with a high level of confidence. The study on orbit development involved a cross-sectional MRI study of 81 Hong Kong Chinese subjects aged from 1 to 42 years. A linear growth rate was found in the first 15 years of life. The orbit grew from around 11.56 cm³ to 25.50 cm³ in 42 years. The orbit reached maturity at around the age of 16 years. To study the relationship between eye size and the volume of the orbit 33 adult subjects with varying degrees of ametropia (+1.00D to -12.75D) underwent MRI of the orbit. Results show that the larger myopic eye was not associated with a larger orbit.
Description: xvi, 170 p. : ill. ; 30 cm.
PolyU Library Call No.: [THS] LG51 .H577M OR 2003 Chau
Rights: All rights reserved.
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