Estimating the prevalence of subretinal drusenoid deposits (SDD) among older adults with healthy macula and age-related macular degeneration (AMD) with multimodal imaging

Abstract

Purpose: To assess SDD prevalence among older adults with healthy macula and early and intermediate AMD using multimodal imaging.

Methods: 651 subjects (1302 eyes) ≥60 years old enrolled in the Alabama Study of Early Age-Related Macular Degeneration (ALSTAR) were assessed using SD-OCT, IR and FAF images, and color fundus photographs. Our strict criteria of SDD required identification on ≥1 en face modality and OCT or on ≥2 en face modalities in the absence of OCT findings. Our expanded criteria of SDD required detection on any imaging modality. Eyes with gradable OCT images were assessed for presence and severity of AMD using the AREDS 9-step scale. The number of subjects excluded from the analysis because of incomplete imaging data was specific to the SDD criteria used. SDD was considered present at the person-level if present even in one eye.

Results: Using the strict criteria, overall sample prevalence of SDD was 32% (200/616); of those with SDD 123/200 (62%) were affected in both eyes. Persons with SDD were older than those without SDD (70.1 vs 68.7 yrs, p<0.0003). When stratified by AMD status, SDD prevalence was 53% in AMD subjects and 23% in subjects without AMD (p<0.0001). Among those with early and intermediate AMD, SDD prevalence was 49% and 80% respectively. After age adjustment, those with SDD were 3.5X more likely to have AMD than those without SDD (95% CI 2.4-5.0). Using the expanded criteria, SDD prevalence was 74% (462/622) with 326/462 (70%) affected in both eyes. There was no age difference between subjects with and without SDD, but SDD prevalence was higher among those with AMD compared to those without (85% vs 69%, p<0.0001) and increased with disease severity. After age adjustment, persons with SDD were 2.6X more likely to have AMD compared to those without SDD (95% CI 1.7-4.1).

Conclusions: SDD is prevalent in over 1/2 of persons with early to intermediate AMD, and is present in about 1/4 of older adults with healthy maculae, even by stringent SDD criteria. A broader definition of SDD increases its prevalence but may lead to overestimation. SDD prevalence is strongly associated with AMD presence and severity and increases with age. Consensus on SDD detection methods is recommended to advance our knowledge of this lesion and its clinical and biologic significance.