Optical Coherence Tomography Angiography Artifacts in Glaucoma

PURPOSE To determine the prevalence of different types of artifacts seen in optical coherence tomography angiography (OCTA) images of healthy and glaucoma eyes and to evaluate the characteristics associated with the increased likelihood of obtaining poor quality images. DESIGN Retrospective study. PARTICIPANTS A total of 649 eyes of 368 healthy, glaucoma suspect, and glaucoma patients. METHODS Angiovue high density (HD) and non-HD optic nerve head and macula OCTA images of participants were evaluated by 4 expert reviewers for the presence of different artifacts including eye movement, defocus, shadow, decentration, segmentation error, blink and Z offset in the superficial vascular layer. Each OCTA scan was designated to have good or poor quality based on the presence of artifacts. The association of demographic and ocular characteristics with the likelihood of obtaining poor quality OCTA images was evaluated using generalized linear mixed model. MAIN OUTCOME MEASURES The prevalence of OCTA artifacts and the factors associated with increased likelihood of capturing poor quality OCTA images. RESULTS 5263 OCTA images were evaluated. Overall, 33.9% of the OCTA images had poor quality. The majority of images with acceptable quality scores (QS>=4) had no artifacts (76.6%). Other images had one (13.6%) or two or more artifacts (9.8%). Older age (P<0.001), male gender (P=0.045), worse visual field mean deviation (P<0.001), absence of eye tracking (P<0.001) and macular scan area (P < 0.001) were associated with a higher likelihood of obtaining poor quality images. In images with acceptable QS, the commercially available quality measures including QS and signal strength index had the area under the receiver operating characteristic curves of 0.65 (95% CI: 0.62, 0.69) and 0.70 (95% CI: 0.68, 0.73) to detect good quality images, respectively. CONCLUSIONS OCTA artifacts associated with poor quality images are frequent, and their prevalence is affected by ocular and patient characteristics. One should not rely solely on the quantitative assessments that are provided automatically by OCTA instruments. A systematic scan review should be conducted to ensure appropriate interpretation of OCTA images. Given the high prevalence of poor quality OCTA images, the images should be reacquired whenever an apparent and correctable artifact is present on a captured image.