EyeCare Plus -- What is ‘20/20 Vision’?

Have you ever wondered why we refer to a person as having ‘20/20 vision’?

When you go to an optometrist, the first thing you usually see is one of those charts on the wall with a big ‘E’ at the top. These charts are called ‘Snellen Eye Charts.’ They’re named after the Dutch ophthalmologist Herman Snellen, who developed them in 1862 to measure visual acuity.

With these charts, Snellen set a standard for measuring visual acuity that is still in place today all over the world. Globally, almost everyone uses the Snellen chart to check visual acuity.

Measurements of visual acuity are known as ‘Snellen fractions.’ The first number – 20 – refers to the distance between the patient and the chart in feet. The second number refers to a line of text on the eye chart. The big letter ‘E’ at the top of the chart designates 20/200 visual acuity.’

The phrase ‘20/20 vision’ is still used colloquially by most Australians, even eye doctors, even though Australia uses the metric system (20 feet equals six metres). Visual acuity is officially recorded as ‘6/6’ in most countries throughout the world.

A common misunderstanding is that ‘20/20 vision’ means ‘perfect vision.’ Actually, it only means that a person has visual acuity within the normal range.

Check out the link below for more information. "https://www.eyecareplus.com.au/what-is-20-20-vision/