Diploscope for the investigation and treatment of disorders of binocular vision

Historical Significance: The diploscope was an instrument designed as a test for binocular vision and muscle balance but found to be equally useful as a home training apparatus for adults and older children. It was in comment use in the first half of the 20th century. For a patient experiencing relative divergence the letters to be read as DOOG. Excessive convergence, on the other hand, would cause them to be read as OGDO. Suppression of left or right eye would cause, respectively, only DO or OG to appear. Ophthalmologist Dr. A. Remy published his invention of the "Diploscope" in 1902 and a monograph on it in 1917 in which he described physiology of vision and methods of research by means of diploscope, the ways of diagnosis and treatment of various forms of squint, amblyopia, pathologic diplopia and some forms of nystagmus.