Measuring dimensions of emmetropic and myopic eyes with magnetic resonance imaging
Atchison, David A., Jones, Catherine E., Schmid, Katrina L., Strugnell, Wendy E. , Riley, Robyn , Pritchard, Nicola, & Pope, James M. (2003) Measuring dimensions of emmetropic and myopic eyes with magnetic resonance imaging. Clinical and Experimental Optometry, 87(1), pp. 45-58.
Magnetic resonance imaging (MRI) is a powerful tool to investigate ocular dimensions, as it is unaffected by assumptions regarding the refractive indices of the ocular media. We used MRI to measure the axial (cornea to retina), horizontal (retina to retina) and vertical (retina to retina) dimensions in emmetropic and myopic eyes (up to -7 D) of more than 50 volunteers aged 18 to 35 years. Volunteers were positioned supine in a General Electric Twin Speed 1.5 Tesla clinical scanner. Images of the right eye were acquired using a 7.5 cm receive-only radio frequency surface coil. A mirror was mounted above the subject at approximately 45 degrees that directed gaze to a bright LED at a distance of approximately six metres straight ahead of the subject. Axial (horizontal through middle of eye) and sagittal (vertical through visual axis) sections were taken with a T1-weighted fast spin echo sequence (TR = 400 ms, TE = 16.8 ms, slice thickness three millimetres, 156 micron x 156 micron pixels, acquisition time 130 seconds). Most eyes showed considerable asymmetry in the axial sections, with lens tilts of up to 10 degrees relative to the visual axis. While the well-known increase in axial length with increase in myopia was an obvious feature of our data, there was considerable variability in shape of both emmetropic and myopic eyes.
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|Item Type:||Journal Article|
|Additional Information:||For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: email@example.com|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health|
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 2003 Optometrists Association Australia|
|Copyright Statement:||The contents of this journal from 1998 to 2005 can be freely accessed online via the journal’s web page (see link).|
|Deposited On:||20 Nov 2006|
|Last Modified:||11 Aug 2011 03:40|
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