Dynamics of Drusen in the ETDRS Grid: A Comprehensive Three-Month Analysis of Movement and Morphology of Drusen in Patients with Intermediate Age-Related Macular Degeneration (iAMD)

Abstract

Purpose : Drusen are a hallmark of intermediate age-related macular degeneration (iAMD). Yet drusen are not stationary. We investigate the dynamic behavior of softdrusen and pseudodrusen within the macular area divided into ETDRS grid over a three-month period in patients with iAMD. We pinpoint the sectors of the ETDRS grid undergoing the most significant changes over time and categorize these changes based on the type of drusen present.

Methods : Eight patients with iAMD were examined over a three-month period. Monthly spectral domain optical coherence tomography (SD-OCT, Heidelberg) scans were conducted. The acquired OCT images for softdrusen were segmented automatically (Heyex, Heidelberg), followed by manual correction of the segmentation to ensure accuracy and reliability in drusen assessment. We measured the volume and thickness between the Bruchs membrane layer and the RPE and we analized the movement of the drusen in the ETDRS grid. For the analysis of pseudodrusen we use a deep algorithmic software (Altris, Inc) where we measure the volume of pseudodrusen and subsequent manual labeling. This study adheres to the Declaration of Helsinki.

Results : All patients included were diagnosed with iAMD AREDS grade 2. No EZ zone alterations in OCT were present.
Mean softdrusen drusen volume at baseline was:
0.47 mm³ +-0.06mm³
Mean Pseudodrusen volume at baseline was:
1.69mm³ +- 0.7mm³
The distribution of softdrusen within the ETDRS sectors was:
17%, 52% and 31% for central, inner ring and outer ring, respectively.
After 3 months there was a total increase of 5% in Softdrusen (-4% in central sector, 7% in inner ring and 7% in outer ring)
After 3 months, the volume of pseudodrusen increased 21% in average in the whole ETDRS grid

Conclusions : The results in patients with softdrusen were heterogeneous (increase and decrease patterns) and in pseudorodrusen were homogeneous (increase). We have observed that in the 4 cases with softdrusen most of the changes occur in the central sector of the ETDRS grid. We support the understanding of drusen formation and movement across the macular region. This may help, supportive to the literature, to better understand iAMD and to interpret possible therapeutic effects on drusen and drusen reduction.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.