Geographic Atrophy Structure-Function Relationships Based on Loss of OCT Outer Retinal Bands and Fundus...

Area of Science:

• Ophthalmology
• Medical Imaging
• Vision Science

Background:

• Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD).
• Assessing the relationship between structural changes in the retina and visual function is crucial for understanding GA progression.
• Optical coherence tomography (OCT) and fundus autofluorescence (FAF) are key imaging modalities.

Purpose of the Study:

• To investigate the association between the loss of outer retinal bands visualized by OCT and deficits in deep visual sensitivity.
• To quantify these structure-function relationships using defect-mapping microperimetry (DMP).

Main Methods:

• A cross-sectional study involving 50 individuals with GA.
• DMP testing was performed to map deep visual sensitivity losses.
• OCT scans were automatically segmented for retinal pigment epithelium (RPE), ellipsoid zone (EZ), and external limiting membrane (ELM) loss.
• FAF imaging was used for GA annotation.
• Image coregistration was employed to link structural and functional data.

Main Results:

• Strong global correlations were found between OCT outer retinal band loss and DMP-detected vision loss (Spearman's ρ = 0.85-0.86).
• Spatial agreement was higher for EZ and ELM loss (Dice Similarity Coefficient [DSC] = 0.64) compared to RPE loss (DSC = 0.60) and FAF-defined GA (DSC = 0.62).
• FAF-defined GA showed strong global correlation (ρ = 0.89) but similar spatial agreement to RPE loss.

Conclusions:

• OCT-derived EZ and ELM loss demonstrate higher spatial agreement with visual sensitivity deficits in GA than RPE loss or FAF-defined GA.
• These findings validate the functional relevance of automatically derived OCT parameters.
• The study supports the utility of these OCT parameters for monitoring GA progression.