The Impact of Drusen on Retinal Sensitivity in non-exudative Age-Related Macular Degeneration: A point-to-point Analysis

Abstract

Purpose : To evaluate the impact of drusen and hyperreflective foci (HRF) on the retinal sensitivity during the course of non-exudative age-related macular degeneration (AMD).

Methods : In a regular follow-up scheme of every three months for one year, retinal sensitivity of 33 eyes of 24 patients with early or intermediate AMD was assessed by mesopic testing using a grid of 45 stimulus points (Nidek MP3, Italy). Eyes were consecutively scanned using Spectralis SD-OCT (scanning area 20°x20°, volume scan 1024x97). All stimuli points were registered exactly to the corresponding OCTs, and drusen as well as HRF were segmented using automated artificial intelligence algorithms. This allowed to calculate the volume and mean thickness of drusen and HRF within a circle of 240µm centered at each stimulus point.

Results : The mean age of the patients was 76.85 years (±6.6). The mean sensitivity was 25.6 dB at baseline and 28.3 dB at 12 months, the mean drusen volume was 0.05mm² and 0.07mm² respectively (p>0.05). Cross-sectional analysis revealed a significant correlation between drusen volume as well as thickness and a worse retinal sensitivity of the overlying photoreceptors (p<0.001, Pearson’s correlation coefficient 0.7). HRF volume was also significantly correlated to a worse retinal sensitivity (p<0.001), however with a lower strength of association. During observation time, no eye showed a distinct drusen regression or converted towards advanced AMD.

Conclusions : A lower sensitivity in eyes of AMD is a well-known fact, however in this survey a direct correlation between drusen size and a lower sensitivity of the overlying photoreceptors is shown by exact measurement of retinal characteristics at the point of stimulus. For HRF a weaker correlation could be identified. However, their impact is more difficult to determine, possibly due to their small size and an often concomitant underlying druse. Further research will investigate the changes of retinal sensitivity during drusen regression and conversion towards advanced AMD.

This is a 2020 ARVO Annual Meeting abstract.