The diaphragm test - the new registering instrument and its mode of use

Historical Significance: NATHANIEL BISHOP HARMAN, MA (Cantab) BCh (Cantab). FRCS (1869-1945) was educated at the City of London School and Cambridge, graduating with a double first in the Natural Sciences Tripos in 1897. He joined the medical school of the Middlesex Hospital, where he came under the influence of William Lang, with whom he worked in the Eye Department as clinical assistant. He did a great deal of anatomical teaching both at Cambridge and in London, before he went to South Africa as a Civil Surgeon in the Boer War. At Moorfields he worked with Treacher Collins. He was elected ophthalmic surgeon to the Belgrave Hospital for Children and later to the West London Hospital, where he was also lecturer in ophthalmology. He is best remembered for the work which he did with James Kerr in low vision through the foundation of special classes in the schools of the L.C.C. education authority, where partially sighted children were segregated and taught by special methods. He was a prolific author, and his 'Aids to Ophthalmology" reached its eighth edition. A number of surgical instruments carry his name. His diaphragm test for binocular vision was demonstrated at the Ophthalmological Society in 1909, and immediately became a popular instrument, of great help in detecting malingerers. [Source obituary Brit J Ophthal 1945. www.ncbi.nlm.nih.gov/pmc/articles/.../pdf/brjopthal00687-0060.pdf.] The diaphragm test has an aperture between the observer and a test target posiitons so that the right and left eyes view only the central portion of the target, while the right eye only sees the left part of the target and vice versa.