Visualizing choriocapillaris using swept-source optical coherence tomography angiography with various probe beam...

Area of Science:

• Ophthalmology
• Biomedical Imaging
• Optical Engineering

Background:

• Imaging the choriocapillaris (CC) is challenging for optical coherence tomography angiography (OCTA) due to limited transverse resolution.
• Understanding the impact of transverse resolution is crucial for accurate CC microvascular network visualization.

Purpose of the Study:

• To explore and demonstrate the effects of transverse resolution on CC microvascular network visualization using OCTA.
• To determine the optimal probe beam size for resolving CC capillary vessels.

Main Methods:

• Utilized three probe beams (1.12 mm, 2.51 mm, 3.50 mm) delivering retinal resolutions of 17.5 µm, 8.8 µm, and 7.0 µm.
• Applied a complex optical microangiography algorithm to extract blood flow in the CC slab.
• Quantified mean retinal pigment epithelium (RPE) to CC distance, CC inter-vascular spacing, and power spectrum magnitude.

Main Results:

• A clearer CC lobular capillary network was resolved with larger beam sizes.
• Image contrast increased by 114% with a 3.50 mm beam compared to a 1.12 mm beam.
• Measurements of RPE-CC distance and CC inter-vascular spacing were more reliable and stable with larger beam sizes.

Conclusions:

• Probe beam size is a critical parameter for effective CC angiography.
• Larger beam sizes are essential for visualizing individual CC capillaries with OCTA.