RESUMEN
PURPOSE: To characterize the features of a peculiar association between reticular pseudodrusen (RPD) and pachychoroid (namely "pachy-RPD") and to compare them with eyes affected by RPD and normal/leptochoroid. DESIGN: Observational, retrospective, case-control study. PARTICIPANTS: Among a cohort of intermediate age-related macular degeneration (AMD) population, we selected eyes with RPD and pachychoroid (i.e. choroidal thickness > 250 µm). A control group of RPD eyes but without pachychoroid (i.e. a choroidal < 250 µm) was included. METHODS: Number and stages of RPD were evaluated in each ETDRS subfield. Furthermore, choroidal perfusion was investigated using choroidal vascularity index (CVI), and choriocapillaris perfusion density (PD) on structural optical coherence tomography (OCT) and OCT-Angiography. MAIN OUTCOME MEASURES: Description of the multimodal imaging features of pachy-RPD and differences with RPD associated with normal/leptochoroid. RESULTS: Among 111 RPD eyes, 37 were included in the pachy-RPD group and 74 in the control group. Pachy-RPD patients were significantly younger than patients with RPD and normal/leptochoroid (mean age 75±16 and 82±7-year-old, respectively)(p=0.002). Total RPD number was comparable between the two groups (p=0.220). However, pachy-RPD eyes showed a significantly higher number of stage 1 RPD in comparison to the controls (p<0.001), and a lower number of stage 3 (p<0.001) and stage 4 RPD (p=0.052). The CVI and choriocapillaris PD were greater in pachy-RPD than in the control group (p<0.001 and p=0.010, respectively). CONCLUSIONS: Pachy-RPD are characterized by a different distribution of RPD stages (i.e. more early stages and lower advanced stages) in comparison to RPD in normal/leptochoroid. Furthermore, pachy-RPD eyes showed greater perfusion indexes of the choroid. These features suggest that the presence of pachychoroid could be a "protective" factor in the RPD evolution to the advanced AMD forms.