Reticular Pseudodrusen Subtypes and Their Interaction With Soft Drusen: Longitudinal Structure-Function Analysis

To evaluate longitudinal structure-function relationships of reticular pseudodrusen (RPD) subtypes and their interaction with soft drusen (SD) on retinal sensitivity (RS) in intermediate age-related macular degeneration.

Retrospective cohort study.

Forty-six eyes of 28 patients diagnosed with intermediate age-related macular degeneration or RPD who underwent microperimetry at two time points 6 to 12 months apart.

RPD presence and subtype (dot or ribbon) and SD were assessed individually at each of 37 early treatment diabetic retinopathy study grid test points on coregistered multimodal imaging. Linear mixed-effects models estimated baseline RS and its change by drusen composition, with test-point location as a fixed effect and adjustment for clinical covariates, plus baseline RS for the change analysis.

Change in RS over follow-up and baseline RS, according to drusen composition.

At baseline, ribbon-type RPD regions showed lower RS than lesion-free regions (mean difference 0.72 ± 0.24 dB, P = .002), whereas dot-type RPD did not differ (P = .120); SD was independently associated with reduced RS (P = .021). No baseline RPD subtype × SD interaction was observed. Longitudinally, a significant interaction was found (P = .005): Regions with both ribbon-type RPD and SD showed the greatest RS decline, whereas RPD subtypes did not differ without SD (all P > .9).

The functional impact of RPD varies by subtype and coexistence with SD. Ribbon-type RPD is associated with greater RS impairment, particularly when combined with SD, highlighting the importance of lesion phenotype in functional risk assessment.