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Yuan Liu, Ali Fard, Homayoun Bagherinia, Mary K Durbin, Jochen Straub; Repeatability and reproducibility of RNFL microvasculature quantification using ZEISS AngioPlex™ OCT Angiography. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1699.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography angiography (OCTA) has proven to be a valuable tool for visualization and quantification of microvasculature in the retina. Clinical studies have suggested that the blood flux metrics and vessel perfusion of the peripapillary retinal nerve fiber layer (RNFL) could lead to a potential mean for management of glaucoma. Here, we report on inter-device and operator variability of these blood flow metrics among normal subjects using ZEISS AngioPlex™ OCT Angiography (ZEISS, Dublin, CA).
A prototype scan pattern consisting of 350-by-350 A-scans over a field of view of 4.5-by-4.5 mm was implemented on AngioPlex OCT Angiography. Normal subjects (N=15) enrolled in the study have both eyes scanned. The volumetric datasets were processed using Optical Micro Angiography (OMAGC) and enface projection techniques to create enface angiography maps. The images were then segmented for vessel area and blood flow metrics over an annulus, with inner and outer diameters of 2 mm and 4.5 mm, centered at the optic disc using the methods described by Chen et al. (DOI: 10.1167/iovs.15-18909).To evaluate the reproducibility and repeatability, each subject was scanned three times on each instrument and using three different instruments, giving a total of 9 scans per eye. The variance of measurements for each eye was calculated, the variances for all individuals were averaged, and the square root was taken. The resultant value was divided by the average of measurements among all eyes to determine the coefficient of repeatability (CR).
Vessel perfusions among all normal subjects were found between 0.349 and 0.412 (average: 0.46, standard deviation: 0.028) with CR of 0.92%. Flux index among all normal subjects were found between 0.343 and 0.519 (average: 0.38, standard deviation: 0.011) with CR of 1.28%. Both metrics were calculated over the entire annulus region.
Our results suggest that the RNFL microvasculature quantification (i.e., vessel perfusion and blood flux index) using AngioPlex OCT Angiography are repeatable and reproducible with variances less than 2% for normal subjects. These findings are crucial for glaucoma disease management using OCTA.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Fig. 1. A representative image of peripapillary RNFL angiography. Quantifications were performed in the area between the two red circles.
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