Purpose To assess the effects of algorithms and covariates in glaucoma diagnosis with optical coherence tomography angiography (OCTA).
Methods In this prospective cross-sectional study, one eye each of 36 normal controls and 64 patients with glaucoma underwent 4.5 mm disc-centred and 6 mm macula-centred OCTA scans. The peripapillary nerve fibre layer plexus capillary density (NFLP-CD) and macular superficial vascular complex vessel density (SVC-VD) were measured using both a commercial algorithm (AngioAnalytics) and a custom algorithm (Center for Ophthalmic Optics & Lasers Angiography Reading Toolkit (COOL-ART)). The nerve fibre layer and ganglion cell complex thicknesses were measured on structural OCT.
Results The overall peripapillary NFLP-CD and macular SVC-VD measured with the two algorithms were highly correlated but poorly agreed. Among the normal controls, the perfusion measurements made by both algorithms were significantly correlated with age. AngioAnalytics measurements were also correlated with signal strength index, while COOL-ART measurements were not. These covariates were adjusted. The diagnostic accuracy, measured as the area under the receiver operating characteristic curve for glaucoma detection, was not significantly different between algorithms, between structural and perfusion parameters and between the peripapillary and macular regions (All p>0.05). The macular SVC-VD in the 6 mm square had a significantly higher diagnostic accuracy than that of the central 3 mm square area (p=0.005).
Conclusions AngioAnalytics and COOL-ART vessel density measurements are not interchangeable but potentially interconvertible. Age and signal strength are significant covariates that need to be considered. Both algorithms and both peripapillary and macular perfusion parameters have similarly good diagnostic accuracy comparable to structural OCT. A larger macular analytic area provides higher diagnostic accuracy.
- diagnostic tests/investigation
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information. None.
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Contributors Concept and design: QSY, DH. Acquisition, analysis or interpretation of data: QSY, LL, PW, AC, EI, YJ, DH. Drafting of the manuscript: QSY. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: QSY. Administrative, technical or material support: YJ, OT, LL, SP, DH. Supervision: YJ, DH. DH had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Funding The study was supported by US National Institutes of Health grants R01 EY023285, R01 EY010145 and P30 EY010572; by unrestricted departmental funding from Research to Prevent Blindness (New York, NY); and by the Champalimaud Foundation (Lisbon, Portugal). The sponsor or funding organisation had no role in the design or conduct of this research.
Competing interests Q.S. QSY, none; O. Tan, OptoVue (F); S. Pi, none; L. Liu, none; P Wei, none; A. Chen, none; E. Ing, none; Y. Jia, OptoVue (F); D. Huang, OptoVue (F, I, P, R).
Provenance and peer review Not commissioned; externally peer reviewed.