A distinction between conventional drusen and pseudodrusen was first made in 1990, and more recently knowledge of pseudodrusen, more accurately called subretinal drusenoid deposits (SDDs), has expanded. Pseudodrusen have a bluish-white appearance by biomicroscopy and color fundus photography. Using optical coherence tomography, pseudodrusen were found to be accumulations of material internal to the retinal pigment epithelium that could extend internally through the ellipsoid zone. These deposits are more commonly seen in older eyes with thinner choroids. Histologic evaluation of these deposits revealed aggregations of material in the subretinal space between photoreceptors and retinal pigment epithelium. SDDs contain some proteins in common with soft drusen but differ in lipid composition. Many studies reported that SDDs are strong independent risk factors for late age-related macular degeneration. Geographic atrophy and type 3 neovascularization are particularly associated with SDD. Unlike conventional drusen, eyes with SDD show slow dark adaptation and poor contrast sensitivity. Outer retinal atrophy develops in eyes with regression of SDD, a newly recognized form of late age-related macular degeneration. Advances in imaging technology have enabled many insights into this condition, including associated photoreceptor, retinal pigment epithelium, and underlying choroidal changes.