Ferdinand Monoyer was a French ophtamologist, known for introducing the dioptre in 1872. He was born in Lyon, France on May 9, 1836. He also died in Lyon on July 11, 1912. He also invented the Monoyer chart, used to test visual acuity. He inserted his name in the chart; reading vertically from bottom to top on each side of the chart, one can read his name.