Retinal blood flow speed quantification at the capillary level using temporal autocorrelation fitting OCTA [Invited].

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Imaging

Background:

• Optical coherence tomography angiography (OCTA) visualizes vasculature but lacks blood flow speed data.
• Accurate measurement of blood flow speed is crucial for diagnosing and monitoring vascular diseases.

Purpose of the Study:

• To present a second-generation Variable Interscan Time Analysis (VISTA) OCTA system.
• To evaluate a quantitative surrogate marker for blood flow speed in retinal vasculature.
• To assess the VISTA OCTA system's capability in imaging human retinal vasculature, including in diabetic retinopathy.

Main Methods:

• Utilized a 600 kHz swept-source OCT prototype for high-speed, high-resolution OCTA acquisition.
• Employed spatially compiled OCTA with a temporal autocorrelation model (ρ(τ) = exp(-ατ)) at the capillary level.
• Measured the temporal autocorrelation decay constant (α) as a blood flow speed marker.

Main Results:

• Demonstrated cardiac pulsatility and assessed the repeatability of the measured α values.
• Showcased distinct α values for different retinal capillary plexuses in healthy eyes.
• Presented representative VISTA OCTA images in eyes affected by diabetic retinopathy.

Conclusions:

• VISTA OCTA provides a quantitative marker (α) for blood flow speed in retinal vasculature.
• The system is capable of imaging retinal vasculature with high resolution and repeatability.
• VISTA OCTA shows potential for clinical applications in diagnosing and managing retinal vascular diseases.