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W. A. Lagreze, M. Gaggl, M. Weigel, M. Bach, R. Munk, T. A. Bley; Quantification of Glaucomatous Optic Atrophy: Retrobulbar Optic Nerve Diameter Measured by High Speed Magnetic Resonance Imaging (MRI) in Comparison to Static Perimetry (SP), Scanning Laser Tomography (SLT), Scanning Laser Polarimetry (SLP), and Optical Coherence Tomography (OCT). Invest. Ophthalmol. Vis. Sci. 2007;48(13):1200. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To compare different, non-invasive surrogate markers for optic atrophy in humans. To assess a novel MRI protocol for ultrafast and precise quantification of the optic nerve diameter (OND) as a measure of retrobulbar optic atrophy.
47 subjects were included. 9 had no eye disease, 16 had preperimetric glaucoma, 11 had a glaucomatous mean visual field defect (MD) of less than 10 dB and 11 subjects of more than 10 dB. Each subject underwent SP by Octopus 101, SLT by HRT, SLP by GDxVCC, Stratus-OCT, and ultrafast high resolution MRI in a 3T scanner. ONDs were determined 5, 10, and 15 mm behind the eye using half a Fourier-acquired single shot turbo spin echo (HASTE)-sequence requiring 1.5 s data acquisition time per slice and providing a spatial resolution of 0.11 mm. A multiple linear regression model was applied to determine 36 intercorrelations (r) among different techniques. ONDs served as independent variables. Dependent variables were 3 different SLT parameters, retinal nerve fiber layer thicknesses measured by OCT and SLP, the Nerve Fiber layer Index measured by SLP, as well as the MD.
For OND measurements taken 5 mm behind the eye, r was uniformely < 0.37 and did not reach statistical significance when corrected for multiple testing. 10 mm behind the eye r increased up to 0.57, being statistically significant in some instances. In the orbital apex 15 mm behind the eye r reached a maximum of 0.80, being statistically significant in most cases. At this location the highest correlation was found for the mean retinal nerve fiber layer thickness measured by OCT.
Retina or optic nerve head related surrogate markers for axonal content are highly correlated to the OND, however only in the orbital apex. Therefore, OND measurements as a marker for axonal loss should be avoided when taken directly behind the eye, e.g. by sonography. Among the different laser scanning devices, OCT correlated best with the OND. HASTE-sequence proved to be very useful for OND quantification.
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