Remembering Ferdinand Monoyer

09 May 2017

Around 75% of the UK population depend on glasses, contact lenses or laser eye surgery to correct their vision. As such many of us will be familiar with the eye chart used at our initial consultation.

Today Google released another thematic doodle celebrating the life of renowned French ophthalmologist Ferdinand Monoyer. Monoyer would be 181 years old today and left an important legacy within the field of ophthalmology. It was in fact Monoyer who invented the eye test chart over 100 years ago.

Ferdinand Monoyer Google Doodle


It was Ferdinand Monoyer’s chart of shrinking letters that first showed each row as representing a different diopter. If Monoyer’s eye chart does not seem immediately familiar then that is because most clinics now use the more popular ‘Snellen’ eye chart which was developed around the same time by Herman Snellen in 1862. Used to test visual acuity, the Monoyer chart is unique in that it hides the name of it’s creator within the lettering. ‘Monoyer’ can be read on the left hand side of the chart reading upwards ignoring the last line and ‘Ferdinand’ on the right hand side. It seems the famous ophthalmologist had a sense of humour!


Monoyer Eye Chart

Monoyer Eye Chart, invented by Ferdinand Monoyer and featuring his name hidden within the letters.


One of Monoyer’s greatest achievements was inventing the dioptre in 1872, the unit of measurement of the optical power of a lens, which is still used today. (We often hear people refer to their refractive error as ‘-2’ for example. What they mean to say is that their refractive error is -2.0D or dioptres.).


Ferdinand Monoyer

Ferdinand Monoyer


Ferdinand Monoyer was born in Lyon, France and moved to the University of Strasbourg in 1871 where he was Associate Professor of Medical Physics at the Faculty of Medicine. He later on taught at the University of Lyon and the University of Nancy. Monoyer passed away on July 11th, 1912 aged 76 but his incredible legacy lives on and was honoured by Google worldwide today.