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The letter chart is usually placed at 6 metres which measures the far distance vision ( or at 3 metres with a mirror in place that increases the distance ) Patients will be asked to read the letters.

 

There is a standard way of writing the results.

The results are measured in a fraction - but it is not too complicated.  Eg 6/24

 

The upper part of the figure tells us at what distance the test was done at - which is usually at 6 metres.

The lower part indicates the size of the letter -  a smaller number here means a smaller letter.

 

For example, the larger letter on a Snellen Chart is  usually the  6/60 letter, and letters gradually decrease in size. A medium sized letter is 6/18.  A tiny letter size  is 6/5

 

Good standard of vision is 6/6 - this is a small letter and is equivalent of twenty twenty vision.

The 20:20 vision term comes from measuring in feet rather than metres

The 6/4 letter is even smaller and indicates excellent vision.

 

If there is difficulty in seeing the smaller letters, the optician will do further tests to determine if lenses will help to improve the vision ie if glasses or contact lenses are needed to see better.

 

 

Different versions of the test chart

Other versions of the chart are available like Tumbling E  or Landolt C . These have the same shape but in different directions. So useful for people who are illiterate or speak a different language.

 

eg in Landolt C chart, the broken circle has a gap, and this is put into different positions on the chart. The person can say or point to which direction the gap is seen. The size of each broken circle  gets smaller further down the chart and so can check the level of vision.

 

There are also charts in different languages like Arabic or Chinese.

 

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Eye Test Chart

The eye test charts measure visual acuity (level of vision) by having different sized letters. These charts do vary in eye care practices - as they do not have the exact same letters or sizes - and some charts may include very tiny letters.

 

A common one is called a Snellen Chart ( named after a Dutch eye doctor)