Longitudinal Macular Structure-Function Relationships in Glaucoma and Their Sources of Variability

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Glaucoma is a progressive optic neuropathy characterized by visual field loss.
• Central structure-function (SF) relationships are crucial for understanding glaucoma's impact on retinal nerve fiber layer thickness.
• Optical coherence tomography (OCT) provides high-resolution macular imaging for quantitative analysis.

Purpose of the Study:

• To review central SF relationships in glaucoma.
• To compare within-session and between-session variability in macular OCT thickness measurements.
• To test if longitudinal within-eye SF variability is less than between-individual variability.

Main Methods:

• Literature review on central SF relationships in glaucoma.
• Analysis of macular OCT thickness measurements (GCL, GCIPL, GCC, FMT) from 38 eyes across 3 sessions.
• Linear mixed models to assess variability components.
• Longitudinal study of 120 eyes with visual fields (VFs) and OCT data.
• Change-point regression and components-of-variance models to analyze within-eye vs. between-individual SF variability.

Main Results:

• Between-session variability contributed 8-36% to total thickness variability.
• Between-individual variability explained 67-78% of total SF variability at various eccentricities.
• SF relationships remained stable over time within individual eyes.

Conclusions:

• Within-session variability is the primary driver of macular thickness changes over time.
• Longitudinal within-eye SF variability is significantly smaller than between-individual variability.
• Studying within-eye SF relationships can improve understanding of glaucoma progression and refine diagnostic algorithms.