What is Drusen?
Small, sharply defined, circular, yellow or white dots lying below the level of the retinal vessels, either discreet or coalesced into larger masses, located throughout the fundus but tending to collect in the region of the macula, around the optic disk, or in the periphery. They may occur in adolescence, but generally do not appear until middle-age or later, consist of hyaline material on the lamina vitrea of the choroid, are considered to be formed by secretions of cells of the pigment epithelium due to degenerative changes and usually do not interfere with vision.
Drusen of the Optic Disk
Sharply defined white or yellow masses of hyaline material on the optic disk, which may protrude over the disk margin and project into the vitreous in grapelike clusters. They are attributed to degenerative changes in the glial cells and may become calcified.
Definition from: Dictionary of Visual Science - Cline Hofstetter Griffin