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The Definition, Rationale, and Effects of Thresholding in OCT Angiography
Emily D Cole1, Eric M Moult2, Sabin Dang1
1New England Eye Center, Tufts Medical Center, Boston, Massachusetts.
Purpose:
To examine the definition, rationale, and effects of thresholding in OCT angiography (OCTA).
Design:
A theoretical description of OCTA thresholding in combination with qualitative and quantitative analysis of the effects of OCTA thresholding in eyes from a retrospective case series.
Participants:
Four eyes were qualitatively examined: 1 from a 27-year-old control, 1 from a 78-year-old exudative age-related macular degeneration (AMD) patient, 1 from a 58-year-old myopic patient, and 1 from a 77-year-old nonexudative AMD patient with geographic atrophy (GA). One eye from a 75-year-old nonexudative AMD patient with GA was quantitatively analyzed.
Main Outcome Measures:
A theoretical thresholding model and a qualitative and quantitative description of the dependency of OCTA on thresholding level.
Results:
Due to the presence of system noise, OCTA thresholding is a necessary step in forming OCTA images; however, thresholding can complicate the relationship between blood flow and OCTA signal.
Conclusions:
Thresholding in OCTA can cause significant artifacts, which should be considered when interpreting and quantifying OCTA images.