Longitudinal changes in ellipsoid zone relative reflectivity in eyes with and without reticular pseudodrusen in intermediate age-related macular degeneration

Abstract

Purpose : The ellipsoid zone (EZ) reflectivity on spectral-domain optical coherence tomography (SD-OCT) imaging is assumed to derive from the photoreceptors’ mitochondria and is regarded to be an indicator for the photoreceptors’ health. Since reticular pseudodrusen (RPD) are a recognized risk factor for progression in age-related macular degeneration (AMD), the purpose of this pilot study was to determine longitudinal changes in EZ relative reflectivity in eyes with and without RPD.

Methods : Horizontal SD-OCT line scans through the fovea of eyes with and without RPD were obtained from an existing AMD natural history cohort, in which SD-OCT was performed every 6 months over 3 years. RPD eyes had definite and extensive presence of RPD on multimodal imaging. Eyes without RPD were those without RPD for the entire study duration. SD-OCT raw images were used to quantify the reflectivity (a grey value ranged 0-1) of the EZ and the external limiting membrane (ELM) at 7 retinal locations up to 8.9° from the fovea. The changes in the EZ relative reflectivity (expressed as EZ:ELM ratio) over time were determined and compared between groups with and without RPD.

Results : Ten subjects (10 eyes) with RPD (mean age of 74.3 years) and 10 subjects without RPD (68.5 years) were included in this pilot study. At baseline, the mean (± standard deviation) EZ relative reflectivity of eyes with and without RPD was 38.3 ± 30.1 and 37.0 ± 20.3, respectively. Over a review period of 3 years, there was a trend of a greater reduction in the EZ relative reflectivity in eyes with RPD (on an average of -12.4 ± 20.8) compared to eyes without RPD (-0.9 ± 15.1, p = 0.1942).

Conclusions : iAMD eyes with RPD showed a trend towards a more pronounced decrease in EZ relative reflectivity over time compared to iAMD eyes without RPD. These findings warrant further studies evaluating the EZ relative reflectivity as a potential biomarker for AMD severity and progression in a larger cohort.

This is a 2020 ARVO Annual Meeting abstract.