Directional Association Between Perilesional Fundus Autofluorescence and Geographic Atrophy Border Expansion

Area of Science:

• Ophthalmology
• Retinal Imaging
• Disease Progression

Background:

• Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD).
• Fundus autofluorescence (FAF) imaging visualizes retinal pigment epithelium (RPE) function.
• Understanding GA border expansion is crucial for predicting disease progression.

Purpose of the Study:

• To investigate the directional relationship between perilesional FAF intensity and GA border expansion.
• To determine if hyperautofluorescence (hyperAF) or hypoautofluorescence (hypoAF) predicts GA growth direction.

Main Methods:

• Analysis of FAF images from 102 untreated eyes at baseline and 6 months.
• Normalized FAF intensity categorized into hyperAF and hypoAF zones (0-250 µm, 0-500 µm).
• Quantification of GA border expansion and assessment of association with FAF density using linear mixed-effects models.

Main Results:

• Higher hyperAF density showed no association with increased GA border expansion (negative regression slopes).
• Higher hypoAF density was significantly associated with greater GA border expansion (positive regression slopes).
• Findings were consistent across different thresholds and in eyes with unifocal lesions.

Conclusions:

• GA expansion is directed towards hypoAF areas, not hyperAF regions.
• Spatial changes in perilesional AF patterns are linked to GA progression.
• Further research is needed to elucidate the biological mechanisms driving this association.