Abstract
BackgroundTo study the impact of image quality on quantitative measurements and the frequency of segmentation error with optical coherence tomography angiography (OCTA).MethodsSeventeen eyes of 10 healthy individuals were included in this study. OCTA was performed using a swept-source device (Triton, Topcon). Each subject underwent three scanning sessions 1–2 min apart; the first two scans were obtained under standard conditions and for the third session, the image quality index was reduced using application of a topical ointment. En face OCTA images of the retinal vasculature were generated using the default segmentation for the superficial and deep retinal layer (SRL, DRL). Intraclass correlation coefficient (ICC) was used as a measure for repeatability. The frequency of segmentation error, motion artifact, banding artifact and projection artifact was also compared among the three sessions.ResultsThe frequency of segmentation error, and motion artifact was statistically similar between high and low image quality sessions (P = 0.707, and P = 1 respectively). However, the frequency of projection and banding artifact was higher with a lower image quality. The vessel density in the SRL was highly repeatable in the high image quality sessions (ICC = 0.8), however, the repeatability was low, comparing the high and low image quality measurements (ICC = 0.3). In the DRL, the repeatability of the vessel density measurements was fair in the high quality sessions (ICC = 0.6 and ICC = 0.5, with and without automatic artifact removal, respectively) and poor comparing high and low image quality sessions (ICC = 0.3 and ICC = 0.06, with and without automatic artifact removal, respectively).ConclusionsThe frequency of artifacts is higher and the repeatability of the measurements is lower with lower image quality. The impact of image quality index should be always considered in OCTA based quantitative measurements.
Highlights
To study the impact of image quality on quantitative measurements and the frequency of segmenta‐ tion error with optical coherence tomography angiography (OCTA)
In the deep retinal layer (DRL), the vessels appeared thicker in the low quality image compared to the high quality images
Motion artifacts were present in one eye in the first and third session (P = 1); banding artifacts were present in 3 eyes in the first and second session and 12 eyes in the third session (P = 0.218)
Summary
To study the impact of image quality on quantitative measurements and the frequency of segmenta‐ tion error with optical coherence tomography angiography (OCTA). Optical coherence tomography angiography (OCTA) is a recently developed clinical tool that has allowed a noninvasive technique to visualize the retinal and choroidal microcirculation in a depth-resolved fashion allowing the superficial and deep retinal layer to be studied separately without the need for dye injection [1, 2]. This technology relies on motion contrast to separate moving from stationary structures to identify blood flow. The aim of this study was to investigate and to quantify the impact of image quality on OCTA quantitative measurements
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