Structure function relationships differ between optic neuritis and glaucoma with comparable optical coherence...

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Optic neuritis (ON) and primary open-angle glaucoma (POAG) are leading causes of optic neuropathy and visual impairment.
• Understanding the structure-function relationship is crucial for diagnosing and managing these conditions.
• Previous studies have not fully elucidated the distinct patterns of visual field defects relative to retinal layer thinning in ON versus POAG.

Purpose of the Study:

• To compare the structure-function relationships between patients with ON and POAG.
• To investigate the correlation between retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) damage and visual field (VF) defects in both conditions.
• To identify differences in how structural damage translates to functional vision loss in ON and POAG.

Main Methods:

• Retrospective analysis of 194 patients (47 ON, 147 POAG) with optical coherence tomography (OCT) and visual field testing data.
• Assessment of RNFL and GCIPL thickness and correlation with VF indices (e.g., mean deviation, VF index).
• Statistical analyses including linear regression with robust error estimation and propensity score matching to compare structure-function relationships, controlling for age and comorbidities.

Main Results:

• Despite comparable RNFL and GCIPL thinning, ON patients exhibited significantly better VF performance than POAG patients (p < 0.001).
• In POAG, VF loss strongly correlated with structural parameters, while ON showed preserved VF even with significant RNFL/GCIPL thinning.
• A significant interaction between disease type and structure-function slopes was confirmed (p < 0.01), persisting across various analyses including propensity score matching and sensitivity analyses.

Conclusions:

• There is a notable dissociation in structure-function relationships between ON and POAG, particularly at RNFL <90 µm and GCIPL <80 µm.
• Optic neuritis preserves visual field function better than primary open-angle glaucoma for equivalent levels of retinal layer thinning.
• These findings emphasize the need for disease-specific diagnostic strategies and further research into the underlying mechanisms of ON and POAG to optimize patient management.