En Face OCT and the Phenotype Characterization of Drusen

PURPOSE. To detect and differentiate the various subtypes of drusen and subretinal drusenoid deposits (SDDs) using single-capture en face spectral-domain optical coherence tomography (SD-OCT) imaging. METHODS. This study was a retrospective case series. Sixty-six eyes of 37 patients with evidence of soft, cuticular, and calcified drusen and SDDs were analyzed. Structural en face OCT images were reconstructed using two 40-μm-thick slabs and one 400-μm-thick slab positioned at different levels above and below Bruch’s membrane. The various features captured with en face OCT at different levels of segmentation were applied to study and classify the subtypes of drusen and SDDs. RESULTS. Dot and ribbon SDDs were clearly captured with outer retina slab segmentation. Soft, cuticular, and calcified drusen were captured with the retinal pigment epithelium (RPE) slab, and all demonstrated a version of the donut sign. The choroidal slab showed reverse donuts representing cuticular drusen, dark lesions due to severe shadowing from calcified drusen, and a slightly attenuated signal representing soft drusen. CONCLUSIONS. En face OCT is a simple and practical tool to phenotype the various classes of drusen and SDDs. Composition differences between the various drusen and SDDs can be captured with en face OCT at varying segmentation levels due to differences in light reflectance and penetration characteristics. These OCT features provide a more in-depth understanding of the various subtypes of drusen and SDDs and can enhance phenotype characterization, which can improve clinical care, clinical trial recruitment, and reading center performance.