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2 Comments 3,713 views Why is normal vision referred to as 6/6?
Kids ASK! about Health & Fitness
When I was a kid, I used to wonder what 6/6 stands for (but I did not have a librarian to ask and no one told me the answer). I would spend time staring at the health cards when the nurses came around to do the yearly checkups and wondering if my eye-sight has deteriorated when I saw something that is not 6/6—I had perfect eyesight until I was 18 years old and considering that I used to read in bed, that was quite an achievement (kids… DO NOT follow my example. DO NOT read in bed lying down).
The accuracy of vision is usually referred to as “Snellen” acuity, after Dutch ophthalmologist, Hermann Snellen (1834-1908). That is the guy who created the chart and letters we now commonly use. The accuracy of vision/visual acuity refers to how clear one’s vision is.
6/6 is actually the distance from the patient in the eye exam room to the eye chart, 6 being 6 meters. Sometimes “20” is used because in the United States, 6 meters would be about 20 feet. If you were in the States and you had normal vision, you would get 20/20, which is the same as having 6/6.
There is actually additional information regarding what 6/6 means exactly. The distance of 6 meters actually corresponds to the visual angle of your eye. However, it is difficult to explain it without diagrams so I shall not reinvent the wheel but rather, direct you to the source of this information, which explains the whole concept of 6/6 quite extensively.
Anatomy, Physiology & Pathology of the Human Eye: Visual Acuity by Ted Montgomery
Sources:
Montgomery, T. Visual Acuity. Retrieved January 9, 2008, from Anatomy, Physiology & Pathology of the Human Eye Web site: http://www.tedmontgomery.com/the_eye/index.html
If you want to find out more information on the eye
For Children:
Eyes and ears by Simon, Seymour
Publisher : New York : HarperCollins Publishers, c2003
Call No. : J 612.8 SIM
Sight by Pringle, Laurence P
Publisher : New York : Benchmark Books, 2000
Call No. : J 597.3 PAR
Human Body by Bingham, Caroline
Publisher : London : Dorling Kindersley, 2003
Call No. : J 612 BIN
All websites are last accessed on 9 January 2008. Please refer to the terms and conditions on the homepages for use.
All images used are extracted from http://www.amazon.com and http://www.bn.com.
For the availability of the above book titles, please check the library catalogue.
Originally answered by Koh Chee Boon, Librarian, Children’s Services
Contributed by Felicia Chan, Librarian, Children’s Services
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This is informative
Why normal vision is known as 6/6?
In Singapore, many students who have done the regular eye tests in schools or opticians outside will know their eyesight is considered healthy if they have a result of 6/6. For anything else, we know it is time to head for fixing a pair of glasses.
A vision of 6/6 means that you can see objects clearly from 6 metres away, as clearly as a person with normal-sighted can see from a distance of 6 metres away. The US equivalent is 20/20 vision where the yardstick is 20 feet. Both are measurement of your visual acuity. In other words, it gauges how sharply or clearly you can see something from a distance.
In the term ‘6/6 vision’, the numerator refers to the distance in metres between where you are standing and the eye chart, usually the classic Snellan chart. On the other hand, the denominator refers to the distance from where a person with typically normal eyesight can see clearly. The numerator is a constant while the denominator gives an indication of your visual acuity.
If you are nearsighted and have a vision of 6/12 vision, it means that objects beyond 6m are fuzzy to you. They are so fuzzy that what you can see from 6m away is what people with normal vision usually can see from 12m away. The bigger the denominator, the weaker is your visual acuity or poorer your eyesight.
When you are told to have 6/6 vision, your vision is considered “normal” as most people can see what you can see from 6m away. However, some people can have vision even better,like 6/3. This means that while they are 6m away from a target, they can see so well that they can see what a normal person can see from 3m away. They are said to have more acute vision than most people and they probably do not need binoculars as much as most other people.
We may have developed myopia due to genetic reasons or bad eye care habits,but we can slow down the degeneration of the eye problem. With good eye exercises or proper diet, our eyesight can become better. We can then enjoy reading more easily!