Retinal ganglion cell layer thickness and local visual field sensitivity in glaucoma

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Early detection and monitoring of glaucoma are crucial for preserving vision.
• Standard automated perimetry (SAP) measures visual field sensitivity, while optical coherence tomography (OCT) assesses retinal nerve fiber layer thickness.

Purpose of the Study:

• To compare visual field sensitivity loss measured by SAP with local retinal ganglion cell layer (RGC) thickness measured by frequency-domain OCT.
• To investigate the correlation between RGC thickness and visual field defects in glaucoma patients.

Main Methods:

• Compared RGC+IPL thickness with SAP total deviation (TD) in 14 glaucoma patients and 19 controls.
• Hand-corrected segmentation of RGC+IPL from 128 horizontal B-scans.
• Adjusted SAP test point locations to correspond with RGC body displacement around the fovea.
• Analyzed data grouped into 5 eccentricities (3.4°–9.7° radius).

Main Results:

• RGC+IPL thickness showed good correlation with SAP loss within 7.2° of the fovea (Spearman ρ = 0.71–0.74).
• Correlation was weaker beyond 7.2° where the RGC layer is thinner.
• A linear model demonstrated a reasonable fit for RGC+IPL thickness and SAP loss within 7.2°.

Conclusions:

• Local RGC+IPL thickness is well-correlated with local sensitivity loss in glaucoma within the central 7.2° of the retina.
• Adjustment for RGC displacement is important for accurate correlation.
• Findings support the use of OCT-derived RGC thickness as a biomarker for glaucoma progression.