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Tobias Batram, Nikolaus Feucht, Chris Lohmann, Mathias Maier; Comparison of foveal avascular zone quantification. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3036.
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© ARVO (1962-2015); The Authors (2016-present)
Since optical coherence tomography angiography (OCTA) has become widely available, many studies have quantified the foveal avascular zone (FAZ) using different systems. We performed a comparison of quantification of the FAZ using fluorescein angiography (FA), a ZEISS Plex Elite 9000 Swept-Source OCTA (ZE), an Optovue XR Avanti OCTA (OP) and the Heidelberg Engineering Spectralis 2 OCTA (HE).We analyzed 24 eyes with a history of macula edema (ME) (15 with diabetic ME, 9 with ME after retinal vein occlusion) and 21 healthy eyes as controls.
We measured the largest diameter (LD) of the FAZ in the FA, in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) with OCTA and the largest diameter orthogonal (LOD) to the LD. We used 3mmx3mm (10°x10°) scans centered on the fovea, the segmentation of the SCP and DCP was checked to be accurate.Statistical analyses include a t-test for comparing the mean of the control and ME group, pearsons correlation coefficient for multiple measurements and a paired t-tests for the mean differences of the measurements obtained by different OCTA systems of the same structure.
The mean LD of the FAZ was significantly larger in the eyes with prior ME than in the control group in the measurements obtained with ZE (300,6µm SD: 66,6µm; p<0,001) and OP (177,7µm SD: 72,0µm; p=0,019) in the DCP. [HE (111,7µm SD: 74,0; p=0,142)]Measurements of the LD in the DCP with ZE (–0.556; p<0,005), OP (-0.466; p=0,01) and HE (-0.42; p=0,019) were correlated with the BCVA as well as the LOD measured in the DCP with ZE (-0,478; p=0,001) and OP (-0,427; p=0,003), and HE (-0,338; p=0,063) showing the same trend.The measurements of the LD in the DCP were correlated between the different OCTA systems, OP with ZE (0,833; p<0,001) and HE (0,751; p< 0,001) and ZE with HE (0,571; p=0,01).The mean differences (MD) of the ZE and OP LD measurements were positive in the SCP (MD: 43,53µm;SD 14,62 µm; p=0,005) and negative in the DCP (MD: -53,5µm SD:22,68µm; p= 0,023).
The significant results as well as the trends were concordant in all measurements of the same structure obtained through the different methods. All plexus specific LD and LOD measurements for all three OCTA systems correlated, but had differences in absolute quantification. Further analysis of quantification (paired t-tests) showed that the mean difference between the systems was not uniform but complex, warranting further investigation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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