Erratum in: “Assessing the accuracy of foveal avascular zone measurements using optical coherence tomography angiography: segmentation and scaling” by Rachel Linderman, Alexander E. Salmon, Margaret Strampe, Madia Russillo, Jamil Khan, and Joseph Carroll (
Trans Vis Sci Tech. 2017;6(3):16, doi:
10.1167/tvst.6.3.16)
The model eye length for the Optovue AngioVue system was incorrectly reported at 24.81 mm. After seeing another paper published reporting an axial length of 23.82 mm,
1 we requested the manufacturer (Optovue, Inc., Fremont, CA) to investigate further. They reported back that the correct model eye length assumed by their AngioVue OCT is 23.95 mm.
All foveal avascular zone (FAZ) area calculations and statistics have been rerun with correctly scaled areas to reflect the different model eye length. While FAZ area values for each individual changed slightly, and thus exact statistics changed, none of the results changed in terms of significance.
In the Abstract, the first two sentences of the Results should read: “FAZ area (mean ± SD) for manual segmentation was 0.257 ± 0.104 mm2, greater than both semiautomatic (0.231 ± 0.0939 mm2) and automatic (0.234 ± 0.0933 mm2) segmentation (P < 0.05). Not correcting for axial length introduced errors up to 31% in FAZ area. Manual area segmentation had better repeatability (0.022 mm2) than semiautomatic (0.046 mm2) or automatic (0.060 mm2).”
Methods, page 3, the axial length assumed for the model eye by the manufacturer was incorrectly listed as 24.81 mm. It should read 23.95 mm.
Figure 1 has been updated, and the P value for panel B should read 0.87. The corresponding text in the results section (page 4) should read: “When correcting the scan size for differences in ocular magnification, the trend is abolished (R2 = 0.0061, P = 0.87, Fig. 1B). The error in FAZ area estimates as a function of axial length is shown in Figure 1C; the average error was 8.29% with a maximum error of 31.36%. The absolute maximum error was 0.07 mm2.”
Results, page 5, bottom of left column should read: “When comparing the automatic with the manual segmentation methods, the mean difference (±SD) was 0.0240 ± 0.0259 mm2 (Wilcoxon signed-rank test, P < 0.0001) with manual being, on average, larger than automatic segmentation for FAZ area. As a percentage of the automatic FAZ area, the difference ranged from 2.2% to 54.4% (the absolute maximum error was 0.145 mm2). The difference between the two methods increased as a function of FAZ area (y = 0.874x + 0.0086; P = 0.0001).”
Results, page 5, bottom of right column should read: “No correlation between age and FAZ area was observed (manual, P = 0.920; semiautomatic, P = 0.996; automatic, P = 0.920), nor was there any correlation between age and FAZ acircularity (manual, P = 0.912; automatic, P = 0.337)”
The Bland Altman plots in Figure 2 have been updated.
The FAZ area values in Tables 1 and 2 have been corrected.
Reference 8 was incorrectly printed, with the beginning of the title coming before the last author's name. It should read: “Nelson LB, Spaeth GL, Nowinski TS, Margo CE, Jackson L. Aniridia. A review. Surv Ophthalmol. 1984;28:621–642.”
Reference 19 was incorrectly printed, with the beginning of the title coming before the last author's name. It should read: “Carpineto P, Mastropasqua R, Marchini G, Toto L, Di Nicola M, Di Antonio L. Reproducibility and repeatability of foveal avascular zone measurements in healthy subjects by optical coherence tomography angiography. Br J Ophthalmol. 2016;100:671–676.”
The article has been corrected online.