Born in 1836 in Lyon, France, Ferdinand Monoyer, was a French ophthalmologist renowned for his groundbreaking research on eye sight which led to him developing the Monoyer chart more than 100 years ago.
Mr Monoyer also introduced a new measurement for vision called the dioptre in 1872 which measures the distance you have to be from text to read it.
Inspired by his father, who was a French military doctor, Mr Monoyer decided to follow in his footsteps and study medicine at the University of Strasbourg.
He worked his way up to become Associate Professor of Medical Physics before moving to become the director of the Ophthalmic Clinic at the University of Nancy. He later worked as Professor of medical physics at the University of Lyon from 1877 to 1909.
Mr Monoyer died at the age of 76 years in 1912 and his tomb is located in the Cimetière de la Guillotière in Lyon.
Just In! Eye test inventor Ferdinand Monoyer has been celebrated by Google with a winking Doodle.
Google's Doodle features a pair of brown and blue eyes taking on the famous Monoyer chart.
And in a special nod to the expert, who would be 181 today, his name is hidden among the letters. Check it out at The Sun.