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Abstract #11446 Published in IGR 6-3
An objective method to define outlier optical coherence tomograms andrepeatability of retinal nerve fibre layer measurements
Bergamin O; Anderson SC; Kardon RHActa Ophthalmologica Scandinavica 2004; 82: 535-543
PURPOSE: To compare the variation in thickness and reflectivity of the retinalnerve fibre layer (RNFL), circumferentially and on repeated testing. METHODS: In 24 normal eyes and 38 eyes with different optic neuropathies or retinopathies,third-party optical coherence tomography (OCT) software defined the RNFL borderbased on the reflectivity pattern across the retina and also providedmeasurements of the mean reflectivity and total retinal thickness in addition to RNFL thickness. A new Gaussian filtering method was implemented so that theweight of the applied filter was varied for each of five individually repeatedscans until an optimum weight filter was determined. RESULTS: The scansrequiring the highest weight filter could be identified as 'outlier' scans thatcontained measurement or alignment artifacts. There was no difference in theweights of filtering needed for normal and abnormal eyes. The RNFL thickness andreflectivity, and retinal thickness were highly correlated with one another innormal and abnormal eyes. CONCLUSIONS: A new Gaussian filtering routine wasdevised that not only defined the most reproducible substructure of the RNFL fora given patient's eye, but also provided a new method of quantifying measurementvariability and identification of scans with measurement or alignment artifacts.
Dr. O. Bergamin. Department of Ophthalmology and Visual Science, Veterans Administration Hospital and University of Iowa, Iowa City, Iowa, USA. oliver.bergamin@usz.ch
Classification:
6.9.2 Optical coherence tomography (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis)
