Relationship between peripapillary vessel density and visual field in glaucoma: a broken-stick model

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Open-angle glaucoma (OAG) is a progressive optic neuropathy.
• Early detection of OAG is crucial for preserving vision.
• Peripapillary vessel density (pVD) and retinal nerve fibre layer thickness (pRNFLT) are key OCT-A and OCT biomarkers.

Purpose of the Study:

• To determine the threshold (tipping point) where pVD, measured by OCT-A, correlates with visual field (VF) loss in OAG.
• To compare the relationship between pVD and VF sensitivity (VFS) versus pRNFLT and VFS.

Main Methods:

• A broken-stick model was employed to analyze data from 166 Korean participants (healthy, suspected glaucoma, early OAG).
• Measurements included peripapillary retinal nerve fibre layer (pRNFL) thickness and pVD via OCT and OCT-A.
• Slopes of the relationship between pVD, pRNFLT, and VFS were calculated above and below identified tipping points.

Main Results:

• Tipping points were identified for pRNFLT in global and regional sectors, with slopes near zero above these points.
• No significant tipping point was found for pVD in either global or regional analyses.
• The relationship between pRNFLT and VFS showed distinct slopes above and below the tipping point.

Conclusions:

• The absence of a tipping point for pVD suggests a potentially linear and stronger correlation with VFS compared to pRNFLT, even in early OAG.
• pVD may serve as a sensitive indicator of glaucomatous changes, potentially preceding significant VF loss.
• Further research into the linear relationship between pVD and VFS is warranted for improved glaucoma monitoring.