Ferdinand Monoyer, French ophthalmologist, invented the Monoyer chart (d. 1912)
Ferdinand Monoyer (9 May 1836 – 11 July 1912) was a French ophthalmologist, known for introducing the dioptre in 1872.
He invented the Monoyer chart, used to test visual acuity. He inserted his name in the random letters of the chart. It appears when one reads vertically from bottom to top on each side.