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Abstract #18130 Published in IGR 9-2
Long-term variability of GDx VCC retinal nerve fiber layer thickness measurements
Medeiros FA; Doshi R; Zangwill LM; Vasile C; Weinreb RNJournal of Glaucoma 2007; 16: 277-281
PURPOSE: To evaluate the long-term variability of GDx VCC retinal nerve fiber layer (RNFL) thickness measurements. METHODS: The study enrolled a cohort of glaucoma suspects who did not develop any evidence of visual field damage or change in the appearance of the optic nerve during an average follow-up of 9.1 ± 3.2 years. Subjects underwent ocular imaging using the commercially available GDx VCC scanning laser polarimeter. At each visit, each eye was imaged three times. Subjects underwent repeated testing with GDx VCC at approximately 12-month intervals during their follow-up. In total, 255 examinations were obtained in 31 eyes of 31 individuals during an average GDx VCC follow-up time of 26.0 ± 8.9 months. A random effects analysis of variance model was used to estimate intraclass correlation coefficients and long-term and short-term variability estimates. RESULTS: Intraclass correlation coefficients ranged from 0.77 to 0.86 for GDx VCC parameters. Short-term variability estimates ranged from 2.45 to 3.89 μm for RNFL thickness parameters, whereas the short-term variability estimate for the parameter Nerve Fiber Indicator was 3.71. Long-term variability was slightly higher than short-term variability for all parameters. For RNFL thickness parameters, long-term variability estimates ranged from 3.21 to 4.97 μm, whereas for the parameter Nerve Fiber Indicator the long-term variability estimate was 4.93. CONCLUSIONS: RNFL measurements obtained with the GDx VCC were found to be highly reproducible in a long-term test-retest situation, supporting the use of this instrument for longitudinal assessment of the RNFL.
Dr. F.A. Medeiros, Department of Ophthalmology, Hamilton Glaucoma Center, University of California, San Diego, CA 92093-0946, USA. fmedeiros@eyecenter.ucsd.edu
Classification:
6.9.1.2 Confocal Scanning Laser Polarimetry (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis > 6.9.1 Laser scanning)
