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 Jutland ( da, Jylland ; german: Jütland ; ang, Ēota land ), known anciently as the Cimbric or Cimbrian Peninsula ( la, Cimbricus Chersonesus; da, den Kimbriske Halvø, links=no or ; german: Kimbrische Halbinsel, links=no), is a peninsula of ...

. In 1864 Skærbæk became part of Germany due to consequences of the

Second Schleswig War The Second Schleswig War ( da, Krigen i 1864; german: Deutsch-Dänischer Krieg) also sometimes known as the Dano-Prussian War or Prusso-Danish War was the second military conflict over the Schleswig-Holstein Question of the nineteenth century. ...

. In 1876 he received his medical doctorate from the

University of Copenhagen The University of Copenhagen ( da, Københavns Universitet, KU) is a prestigious public research university in Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in Scandinavia after Uppsala Unive ...

, and in 1879 became an assistant to Edmund Hansen Grut (1831-1907) at the Havnegade eye clinic. After Grut's retirement in 1896, he became director of the clinic, as well as being the second professor of

ophthalmology Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medic ...

at the University of Copenhagen, a position he would maintain until his retirement in 1910. Bjerrum made contributions regarding pathogenetic research of

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

, 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 The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

. He was particularly focused on the subtleties of the central 30° of the

visual field The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point ...

rather than the standard

perimetry A visual field test is an eye examination that can detect dysfunction in central and peripheral vision which may be caused by various medical conditions such as glaucoma, stroke, pituitary disease, brain tumours or other neurological deficits. V ...

tests that many of his contemporaries favored. As a result of his campimetric tests he discovered a small glaucomatous

scotoma A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision. Every normal mam ...

that was to become known as a " Bjerrum scotoma", which is a visual field defect that goes by several other names, such as "sickle scotoma", "arcuate scotoma" or "scimitar scotoma". Other eponyms named after Bjerrum include: * Bjerrum tangent screen: Screen used to assess the central 30° of the visual field. * Bjerrum's area: An arcuate region that extends above and below the blind spot to between 10° and 20° of

fixation point In geometrical optics, a focus, also called an image point, is a point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blu ...

. After Bjerrum's retirement in 1910, his work in campimetry was continued by his assistant, Henning Rønne (1878-1947). Jannik Petersen Bjerrum was the father of the chemist Niels Bjerrum and the brother of physicist

Kirstine Meyer Kirstine Bjerrum Meyer (12 October 1861 – 28 September 1941) was a Danish physicist and was first woman from her country to earn a doctorate in natural sciences. Biography Kirstine Bjerrum was born in Skærbæk, Denmark and died in Hellerup ...

References

Ophthalmology Hall of Fame
(biography)

Imaging and the Perimetry Society, The age of isopter perimetry: Bjerrum and the tangent screen *

External links

* {{DEFAULTSORT:Bjerrum, Jannik Petersen 1851 births 1920 deaths People from Tønder Municipality Danish ophthalmologists University of Copenhagen faculty University of Copenhagen alumni