Peripapillary Vessel Density Mediates the Relationship Between Axial Length and Visual Field Damage in Glaucoma

Area of Science:

• Ophthalmology
• Vascular Biology
• Glaucoma Research

Background:

• Axial myopia is a known risk factor for glaucoma.
• The precise mechanisms linking axial length (AL) to visual field (VF) damage are not fully understood.
• Investigating intermediary factors like peripapillary vessel density (pVD) is crucial.

Purpose of the Study:

• To determine the extent to which peripapillary vessel density (pVD) mediates the relationship between axial length (AL) and visual field (VF) outcomes in primary open-angle glaucoma (POAG) patients.
• To explore the role of microvascular changes in glaucoma pathophysiology.

Main Methods:

• Cross-sectional pilot study with two cohorts of POAG eyes (n=26 and n=71).
• Optical coherence tomography angiography used to quantify peripapillary vessel density (pVD).
• Mediation analyses performed using regression, adjusting for covariates, with bias-corrected bootstrap confidence intervals for indirect effects.

Main Results:

• Inferior-temporal pVD significantly mediated the association between AL and all measured VF outcomes (mean deviation, pattern standard deviation, visual field index) in both cohorts.
• Additional sectors showed mediation in the expanded cohort, indicating potentially widespread vascular compromise.

Conclusions:

• Peripapillary microvascular compromise plays a significant role in mediating the effect of axial length on glaucomatous visual field loss.
• Findings support a biomechanical-vascular model for POAG, applicable across varying axial lengths.