Projection-resolved optical coherence tomography angiography (PR-OCTA) of hard exudates.

Top row: Spectral domain-OCT (SD-OCT), projection artifact removal (PAR) OCTA and PR-OCTA scans at thresholds of 0.3, 0.5 and 0.7 of case 13. The flow artifact signal is seen in PAR-OCTA in the hard exudate (yellow ellipse). There is gradual decrease in the flow signal intensity with increasing PR-OCTA threshold from 0.3 to 0.5 (yellow ellipses), manifested by a decrease in red pixel percentage from 38.4% to 34.5%. The flow signal disappears at a threshold of 0.7 (cyan ellipse), where the red pixel percentage is equal to green and blue pixels (33% each), thus confirming it is projection artifact and not true flow. Bottom row: SD-OCT, PAR-OCTA and PR-OCTA scans at thresholds of 0.3, 0.5 and 0.7 of case 17. The flow artifact is seen in PAR-OCTA in the hard exudate (yellow circle). The flow artifact in this eye disappears at PR-OCTA threshold 0.5 (cyan circle) compared to 0.7 in the top row. The red pixel percentage drops from 35.9% in 0.3 to 33% in 0.5, to be equal to that of green and blue, confirming its disappearance.