Structure-function relationships using spectral-domain optical coherence tomography: comparison with scanning laser...

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Assessing the relationship between retinal nerve fiber layer (RNFL) thickness and visual field sensitivity is crucial for glaucoma diagnosis and monitoring.
• Spectral-domain optical coherence tomography (OCT) and scanning laser polarimetry (GDx VCC) are common imaging techniques used to measure RNFL thickness.

Purpose of the Study:

• To compare the regional structure-function relationships between RNFL thickness and visual field sensitivity using OCT and GDx VCC.
• To determine which imaging modality and regression model (linear vs. logarithmic) best captures this relationship.

Main Methods:

• A prospective cross-sectional study included 120 eyes (40 healthy, 40 suspected glaucoma, 40 glaucoma).
• RNFL thickness was measured using Cirrus-OCT and GDx VCC, with detailed sector analysis.
• Correlations between RNFL thickness and visual field sensitivity were analyzed using linear and logarithmic regression. Receiver operating curve (ROC) areas were calculated.

Main Results:

• Structure-function correlations were significantly stronger with spectral-domain OCT (r² up to 0.726) compared to GDx VCC (r² up to 0.362).
• Logarithmic regression provided a better fit for the structure-function relationship than linear regression for both instruments.
• OCT demonstrated superior diagnostic performance, with the largest ROC areas for superior RNFL thickness in glaucoma patients (0.963) and average RNFL thickness in suspected glaucoma patients (0.888).

Conclusions:

• Spectral-domain OCT offers a more robust assessment of the structure-function relationship in glaucoma compared to scanning laser polarimetry.
• The relationship between RNFL thickness and visual field sensitivity is better described by a logarithmic model.
• OCT and GDx VCC measurements are not interchangeable for clinical use.