Abstract
Purpose :
Soft drusen (SDr) and retinal pigment epithelium (RPE) changes are a hallmark of intermediate age-related macular degeneration (iAMD), and both show autofluorescence (AF) properties which often change when AMD progresses. Quantification of these AF changes might enable to better predict drusen stage and RPE health. Therefore, in this study we used quantitative fundus autofluorescence (QAF) to quantify RPE and drusen complex (RPEDC) AF in SDr of iAMD patients.
Methods :
13 eyes from 13 patients (mean + STD age 71.1 ± 6.7 years; 8 females) were imaged using QAF and optical coherence tomography (OCT; macula scan, 252 scans, ART = 25, 30X25 mm). OCT scans and QAF images were software assisted aligned, then SDr were marked on the individual OCT scans. SDr area and the adjacent area were subdivided in 0.01 mm isohulls and QAF values and corresponding RPEDC thicknesses were extracted. Furthermore, deviation of SDr AF to topographic mean AF levels from 30 iAMD eyes were computed. Finally, the mean, standard deviation (STD) of QAF and the pearson correlation coefficient of QAF intensities and RPEDC were calculated.
Results :
On average, 376 ± 335 SDr annotations were compiled per eye. The average AF of all SDr was decreased by 0.31 ± 0.13 STDs. The average RPEDC thickness was 67.7 ± 20.6 µm (normative value: 50.0 µm). Both RPEDC thickness and QAF intensities increased towards the drusen apex. However, at the edge of SDr, QAF intensities were only slightly decreased (by 0.16 ± 0.04 at distance 200µm) and decreased further with increasing distance. When analyzing the correlation of RPEDC and QAF within the SDr, a high significant correlation could be found between height and QAF levels (R=0.978, p< 0.001).
Conclusions :
SDr show reduced QAF levels when compared to the topographic mean in iAMD eyes. Peak AF of the SDr can be found at the drusen apex which might be due to either drusen material within or due to changes above, i.e., the overlying RPE, or a combination of both.
SDr showed a proportional hyper-AF ring, as reported for non QAF imaging (PMID: 10670481). Our ongoing studies examine longitudinal changes in QAF of the RPEDC to better determine SDr heterogeneity, SDr life cycle, and RPE health in iAMD.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.