PLX Academy · News · 01 April 2022
Eye test chart
French eye doctor, Ferdinand Monoyer developed a unit of measurement for the optical power of a lens called a diopter.
Anyone who has had an eye test will have been asked to read rows of letters, which become progressively smaller and harder to recognize by their optician. This eye test chart was first invented by Ferdinand Monoyer, a French opthalmologist, or eye doctor, who would have been 185 years old today.
Monoyer, developed a unit of measurement for the optical power of a lens called a diopter. In his famous eye chart, each row represents a different diopter which measures the distance you would have to be from the text to read it. Monoyer, also inserted his name into the chart. ‘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 humor!
For example, around 75% of the UK population depends on glasses, contact lenses or laser eye surgery to correct their vision. Without Monoyer’s ideas, it may have taken longer for us to perfect eye tests. With his chart and the invention of diopters, Monoyer made a vital contribution to opthalmology and his impact has lasted to the present day.
Ferdinand Monoyer was born in Lyon, France, 9 May 1836. He moved to the University of Strasbourg in 1871 where he was Associate Professor of Medical Physics at the Faculty of Medicine. Later, he 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. The house in Lyon where Monoyer lived, has been preserved and is open to visitors for special events such as picnics and walks in the gardens.