Jannik Petersen Bjerrum (26 December 1851 – 2 July 1920) was a Danish ophthalmologist who was a native of Skærbæk, a town in the southernmost part of Jutland.
In 1876 he received his medical doctorate from the University of Copenhagen, and in 1879 became an assistant to Edmund Hansen Grut (1831-1907) at the Havnegade eye clinic.
Bjerrum made contributions regarding pathogenetic research of glaucoma, and performed extensive investigations involving campimetry.
He was interested in the correlation between visual perception of form and the resolving power in localized regions of the retina.
He was particularly focused on the subtleties of the central 30° of the visual field rather than the standard perimetry tests that many of his contemporaries favored.