Extravascular Motion Signal Detected by OCT Angiography Indicates Altered Vascular-Tissue Biomechanical Interactions...

Area of Science:

• Ophthalmology
• Medical Imaging
• Cardiovascular Physiology

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Optical coherence tomography angiography (OCTA) is an advanced imaging technique for visualizing retinal vasculature.
• Quantifying physiologic changes in glaucoma remains a challenge.

Purpose of the Study:

• To identify and characterize a novel extravascular motion (EVM) signal using OCTA.
• To test if EVM can quantify physiologic changes in glaucomatous eyes.

Main Methods:

• Analysis of existing OCTA data from experimental glaucoma (EG) in rhesus macaques.
• Manual segmentation of OCTA scans to quantify EVM lines and classify blood vessels.
• Statistical analysis using two-way ANOVA and linear regression.

Main Results:

• EVM signals appear as line segments along B-scan lines, estimating heart rate.
• EVMs are more frequent near arteries and in EG eyes compared to control eyes.
• EVMs increase with intraocular pressure (IOP) and are influenced by IOP even after adjustment.

Conclusions:

• A novel OCTA EVM signal represents pulsatile tissue displacement linked to the cardiac cycle.
• EVMs are more prevalent in experimental glaucoma eyes and influenced by IOP.
• EVMs may indicate altered biomechanical properties of retinal vasculature and parenchyma in glaucoma.