At the ophthalmologist, the main part of the examination is to read letters of different sizes on a board.
The method developed by Ferdinand Monoyer began at the end of the 19th century and is still used today.
Europe 1 tells you the story of this invention.
Whether you go to the ophthalmologist for regular follow-up or a simple routine check-up, you will have noticed the ceremonial surrounding eye tests.
You will receive a small puff of air in your eye to verify that the reflexes are still there, but you will also likely be required to read letters of decreasing size on what is called an optometric chart.
The way you read them will tell you what the level of your eyesight is.
However, this tool has not always existed: here is its story.
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Symbols before letters
In the 18th century, vision correction was done in a fairly traditional way.
People with vision problems had to make the diagnosis themselves.
They would try on glasses one by one until they found the ones they were most comfortable with.
Some merchants gave indications, unfortunately very unreliable, by scratching on a corner of the glasses an age at which glasses were the most recommended.
They assumed that an age group corresponded to a sight problem.
In the middle of the 19th century in Holland, Dr. Franciscus Donders had the idea to take a list of standardized shapes, place them at a fixed distance from patients and ask them what they saw.
The principle of sight tests was born.
However, the latter used symbols and not letters, making the exercise a little too easy and often distorted.
In a very short time, the use of letters is essential ... never to change.
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Double acrostic
At the same time, and without a link between the two discoveries being attested, the French doctor Ferdinand Monoyer developed a test using the same principle.
Except that he mixes the letters in large and small characters.
The Monoyer test is still used today by French ophthalmologists.
Facetious, Ferdinand Monoyer hid a little message in his invention.
In its standardized form, his test features large letters at the bottom and smaller at the top ... and a double acrostic.
At the beginning of each line, reading the letters from bottom to top shows: F - E - R - D - I - N - A - N - D. At the end, the same diagram appears M - O - N - O - Y - E - R. As you will have understood, not content with developing a test that survives him more than a hundred years later, Ferninand Monoyer decided to freeze his own name there for eternity.