Late 19th century ophthalmoscopy tool. Ophthalmoscopic tools are used to examine the interior of the eye and measure its optical properties. This is a Fick tonometer dating from 1895. This instrument measures the internal pressure of the eyeball (a process known as ophthalmic tonometry). Made by the French Boulitte company, the original design for the instrument seen here was by an Adolf Fick. The German physiologist Adolf Eugen Fick (1829-1901) worked on tonometry during this period. His nephew was a German ophthalmologist with a similar name, Adolf Gaston Eugen Fick (1852-1937). The device shown here is a modified design by Oswalt.