Optic disc drusen are acellular, calcified deposits within the optic nerve head. Optic disc drusen are congenital and developmental anomalies of the optic nerve head, representing hyaline-containing bodies that, over time, appear as elevated, lumpy irregularities on the anterior portion of the optic nerve. [ http://www.ncbi.nlm.nih.gov/pubmed/22787500 http://www.ncbi.nlm.nih.gov/pubmed/23658477 ]