The method for testing how well we are able to see without the help of glasses hasn't changed a great deal in over a century.
It follows a basic principle: read from rows of gradually shrinking letters until you're unable to distinguish the shapes any more. From this, opthamologists can determine people's clarity of vision.
The most well known test is the Snellen chart. It was introduced around the same time as a rival test called the Monoyer chart.
Named after its creator Ferdinand Monoyer, the Monoyer chart was designed more than 100 years ago and was the first eye test to use a decimal system.
The 9th of May would be Monoyer's 181st birthday, he has been honoured with a Google Doodle.
Who was Ferdinand Monoyer?
Monoyer, who was born in France in 1836, pioneered the way we measure eye sight. He grew up in Lyon before moving to the University of Strasbourg in 1871. He eventually returned to Lyon, were he died aged 76 in 1912.
He is best known for creating the Monoyer chart, as well as introducing the dioptre as a measurement for visual clarity.
"He developed the dioptre, the unit of measurement for vision that's still used today," said Google. "The dioptre measures the distance you'd have to be from text to read it. Most notably, Monoyer devised an eye chart where every row represents a different dioptre, from smallest to largest."
11 things you didn't know about your eyes
1. A human eye weighs approximately 28g, is 2.5cm wide and has six muscles
2. They hardly grow from the time when you're born
3. Eyes can only see the colours red, blue and green. They make all others from these three
4. They can spot around 50,000 shades of grey
5. The average blink takes one tenth of a second
6. People blink around 12 to 17 times per minute
7. It takes an eye 48 hours to heal a scratch
8. There are around 137 million rod and cone cells in you eyes
9. The muscle that controls the eye is the most active in the body
10. Images arrive at the eye upside down, split in half and distorted
11. Peripheral vision is low quality and almost black-and-white
From Telegraph.co.uk
It follows a basic principle: read from rows of gradually shrinking letters until you're unable to distinguish the shapes any more. From this, opthamologists can determine people's clarity of vision.
The most well known test is the Snellen chart. It was introduced around the same time as a rival test called the Monoyer chart.
Named after its creator Ferdinand Monoyer, the Monoyer chart was designed more than 100 years ago and was the first eye test to use a decimal system.
The 9th of May would be Monoyer's 181st birthday, he has been honoured with a Google Doodle.
Who was Ferdinand Monoyer?
Monoyer, who was born in France in 1836, pioneered the way we measure eye sight. He grew up in Lyon before moving to the University of Strasbourg in 1871. He eventually returned to Lyon, were he died aged 76 in 1912.
He is best known for creating the Monoyer chart, as well as introducing the dioptre as a measurement for visual clarity.
"He developed the dioptre, the unit of measurement for vision that's still used today," said Google. "The dioptre measures the distance you'd have to be from text to read it. Most notably, Monoyer devised an eye chart where every row represents a different dioptre, from smallest to largest."
11 things you didn't know about your eyes
1. A human eye weighs approximately 28g, is 2.5cm wide and has six muscles
2. They hardly grow from the time when you're born
3. Eyes can only see the colours red, blue and green. They make all others from these three
4. They can spot around 50,000 shades of grey
5. The average blink takes one tenth of a second
6. People blink around 12 to 17 times per minute
7. It takes an eye 48 hours to heal a scratch
8. There are around 137 million rod and cone cells in you eyes
9. The muscle that controls the eye is the most active in the body
10. Images arrive at the eye upside down, split in half and distorted
11. Peripheral vision is low quality and almost black-and-white
From Telegraph.co.uk
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