Nerve Fiber Flux Analysis Using Wide-Field Swept-Source Optical Coherence Tomography

Area of Science:

• Ophthalmology
• Medical Imaging
• Neuroscience

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Accurate quantification of retinal nerve fiber layer (RNFL) damage is crucial for early glaucoma detection.
• Current imaging techniques have limitations in quantifying nerve fiber loss along arcuate pathways.

Purpose of the Study:

• To develop and validate a novel method for quantifying nerve fiber trajectories over arcuate courses in the peripapillary region.
• To utilize optical coherence tomography (OCT) for extended peripapillary area imaging.
• To introduce nerve fiber flux (NFF) as a quantitative measure of nerve fiber integrity.

Main Methods:

• Employed 8x8-mm volumetric OCT scans centered at the optic disc.
• Introduced nerve fiber flux (NFF) representing cross-sectional area perpendicular to nerve fibers.
• Developed an iterative algorithm to trace nerve fiber trajectories, assuming flux conservation and accounting for macular connections.

Main Results:

• The algorithm successfully identified consistent NFL track patterns in healthy eyes.
• In glaucomatous eyes, NFF showed significant correlation with visual field sensitivity in arcuate sectors (Spearman ρ = 0.53-0.62).
• Focal nerve fiber loss in glaucoma presented as uniform NFF defects along expected arcuate trajectories.

Conclusions:

• A flux conservation-based algorithm effectively derives peripapillary nerve fiber trajectories.
• Nerve fiber flux (NFF) maps enable visualization of focal defects and quantification of sector nerve fiber loss from wide-area OCT scans.
• NFF offers a cumulative measure of volumetric loss, potentially enhancing focal glaucoma damage detection.