Association Between Choroidal Thickness and Drusen Subtypes in Age-Related Macular Degeneration

Purpose: To evaluate the association between the choroidal thickness (CT) and the characteristics of drusen and exudative age-related macular degeneration (AMD) sub-phenotypes in Asian and white populations.

Design: Retrospective clinical cohort study.

Participants: We included 359 patients with drusen in at least 1 eye, including 145 eyes from Asian patients and 214 eyes from white patients.

Methods: Drusen were graded into 3 subtypes-pachydrusen, soft drusen, and pseudodrusen-on the basis of color fundus photographs. Subfoveal CT was measured using spectral domain OCT. In patients with exudative AMD in their fellow eyes, the lesions were classified into polypoidal choroidal vasculopathy (PCV), choroidal neovascularization (CNV), or type 3 neovascularization.

Main Outcome Measures: Associations among race, CT, and AMD expression.

Results: There were significantly more eyes with pachydrusen (25.5% vs. 8.4%; P < 0.001) and fewer eyes with pseudodrusen (17.2% vs. 39.7%; P < 0.001) in the Asian cohort than the white cohort. Eyes with thicker choroid (≥250 μm) were more likely to have pachydrusen than soft drusen or pseudodrusen in both cohorts (62.2% vs. 31.3% vs. 8.0%, P < 0.001 in the Asian cohort; 94.4% vs. 37.8% vs. 18.8%, P < 0.001 in the white cohort); this association remained significant after adjusting for age, gender, and fellow eye neovascularization sub-phenotype (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.01-1.11; P = 0.026 in the Asian cohort and OR, 1.08; 95% CI, 1.04-1.13; P < 0.001 in the white cohort). In the Asian cohort, patients with PCV were more likely to have thicker choroid (P = 0.041) and pachydrusen (P < 0.001 compared with pseudodrusen, P = 0.039 compared with soft drusen).

Conclusions: Asian patients with AMD are more likely to have pachydrusen and less likely to have pseudodrusen than white patients. Choroidal thickness is independently associated with drusen subtype, whereby thicker choroid is associated with pachydrusen and PCV, and thin choroid is associated with pseudodrusen.