Correlation Study Between Drusen Morphology and Fundus Autofluorescence

Abstract

Purpose: To correlate drusen morphology and outer retinal status with autofluorescence (AF) imaging in patients with intermediate age-related macular degeneration. Methods: Drusen type and morphology were analyzed using color fundus photography and spectral-domain optic coherence tomography, whereas fundus AF was used for drusen AF evaluation. Additional structural changes on spectral-domain optic coherence tomography, such as disruption of external limiting membrane, ellipsoid zone, and retinal pigment epithelium/Bruch membrane complex, as well as the presence of choroidal hypertransmission at correspondent locations were also evaluated and correlated with fundus AF findings. Spearman's correlation coefficient was used to analyze the correlation between spectral-domain optic coherence tomography morphological characteristics of drusen and AF appearance of the corresponding drusen. Strength of correlation was calculated (r), and a P value < 0.05 was considered statistically significant. Results: Two hundred and twenty-eight drusen from 53 eyes of 53 patients were analyzed, 130 soft drusen (57.02%) and 98 cuticular drusen (42.98%). Sixty percent of the drusen were isoautofluorescent (n = 136), 35% hyperautofluorescent (n = 80), and 5% hypoautofluorescent (n = 12). We found positive correlation between drusen AF and hyperreflective foci (r = 0.4). Outer retinal layers morphology (external limiting membrane and ellipsoid zone status and hypertransmission) also correlates with autofluorescent findings (r = 0.3). Conclusion: Multimodal imaging reveals a broad spectrum of ultrastructural changes, which may reflect different stages in the evolution of drusen. Our results suggest that drusen morphological characteristics and autofluorescent findings are correlated but other factors or cofactors may be involved. The described correlations will help us understand new progression biomarkers of nonexudative age-related macular degeneration.

Age-Related Macular Degeneration: Pathophysiology, Management, and Future Perspectives

“…Multimodal imaging data are beginning to reveal the intricacies of drusen evolution in AMD and may ultimately yield more precise biomarkers of disease progression. In a recent imaging study that included patients with intermediate AMD, drusen autofluorescence characteristics were found to be weakly correlated with HRF and with morphology of the outer retinal layers [34].…”

Changes in drusen‐associated autofluorescence over time observed by fluorescence lifetime imaging ophthalmoscopy in age‐related macular degeneration

“…In a recent paper, Floes et al found 35% of soft or cuticular drusen to be hyperautofluorescent and 5% to be hypoautofluerescent (Flores et al, 2021). At these drusen, disruption of the integrity of the external limiting membrane, ellipsoid zone, and RPE–Bruch's membrane complex were found much more frequently than atop isofluorescent drusen, indicating the risk for AMD progression.…”

“…(Guymer et al, 2020; Sadda et al, 2018) While the protein (Crabb et al, 2002; Schütt et al, 2002; Umeda et al, 2005) and lipid composition (Curcio et al, 2001; Curcio et al, 2010; Curcio et al, 2011; Sarks et al, 1988; Wang et al, 2009) of drusen and RPE was studied extensively, there is still a debate on the contribution of drusen to fundus autofluorescence (FAF). While histologic studies show a weak autofluorescence of drusen with short emission wavelength (Hammer et al, 2008; Marmorstein et al, 2002; Tong et al, 2016) and long FAF lifetimes in fluorescence lifetime microscopy (Schultz et al, 2020), drusen can be either hypo‐, iso, or hyperautofluorescent in vivo (Flores et al, 2021; Gobel et al, 2016). This can be associated with disruption of the integrity of the external limiting membrane, ellipsoid zone, and RPE–Bruch's membrane complex and may indicate the risk for AMD progression (Flores et al, 2021).…”

“…While histologic studies show a weak autofluorescence of drusen with short emission wavelength (Hammer et al, 2008; Marmorstein et al, 2002; Tong et al, 2016) and long FAF lifetimes in fluorescence lifetime microscopy (Schultz et al, 2020), drusen can be either hypo‐, iso, or hyperautofluorescent in vivo (Flores et al, 2021; Gobel et al, 2016). This can be associated with disruption of the integrity of the external limiting membrane, ellipsoid zone, and RPE–Bruch's membrane complex and may indicate the risk for AMD progression (Flores et al, 2021). Furthermore, the status of the overlying RPE is important.…”