OCT angiography (OCTA) detects retinal blood flow based on which principle?
- A Decorrelation of OCT signal between repeated B-scan acquisitions caused by moving erythrocytes ✓
- B Doppler shift of infrared light from moving erythrocytes
- C Fluorescent emission from intravenous dye leaking through vessel walls
- D Laser speckle variability in reflected light intensity
Correct answer: A. Decorrelation of OCT signal between repeated B-scan acquisitions caused by moving erythrocytes
Explanation
OCTA detects motion (flow) by comparing multiple sequential OCT B-scans obtained at the same location; moving erythrocytes cause decorrelation (variation) of the speckle signal between scans while static tissue remains correlated. This decorrelation signal is used to generate a three-dimensional angiogram without intravenous dye. Pure Doppler OCT uses frequency shift. Dye-based leakage is the FFA principle. Laser speckle contrast imaging is a separate modality.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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