Abstract
Purpose: :
To assess the improvement in reproducibility of 100 versus 16 averaged images by Automatic Real Time-function (ART) using SpectralisTM Spectral Domain-Optical Coherence Tomography (SD-OCT, Heidelberg Engineering GmbH, Heidelberg, Germany) in retinal nerve fiber layer thickness (RNFL) circle scan-measurements.
Methods: :
RNFL-SD-OCT scans were obtained in healthy patients of at least 18 years of age and with a refractive error less than ±5.00dpt spherical and ±1.50dpt cylindrical. On each subject three scans with 16 (ART16) and three scans with 100 (ART100) averaged images by ART-function were done centered manually on the optic disc. RNFL thickness was measured in 4 quadrants around the optic disc. In addition, the overall mean RNFL thickness was assessed. Coefficients of variation (COV) were calculated.
Results: :
Twenty-nine (14 right) eyes were examined. Mean age was 45.1 ± 19.3 years. Global RNFL was 100.8µm ± 11.0 for ART100 and 100.7µm ± 10.6 for ART16, respectively (p=0.41). In the superior quadrant RNFL was 124.6µm ± 23.2 for ART100 and 127.0µm ± 19.5 for ART16, respectively (p=0.07), in the temporal quadrant 73.8µm ± 15.7 and 73.4µm ± 12.9, respectively (p<0.01), in the inferior quadrant 129.4µm ± 17.7 and 127.8µm ± 16.5, respectively (p=0.01) and in the nasal quadrant 73.1µm ± 11.8 and 74.8µm ± 11.1, respectively (p=0.02). COVs for ART100 ranged from 10.9% to 21.3% and from 10.6% to 17.6% for ART16.
Conclusions: :
Previously only up to 16 images could have been averaged by ART-function. In the new software version 5.3 of Heidelberg SpectralisTM SD-OCT up to 100 images can be averaged using ART. Imaging quality is now significantly improved but thus does not lead to improvement in measuring RNFL.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer • optic nerve