Visual acuity describes how well you see detail with your central vision. This is usually measured using a special chart with rows of letters that start with one big one at the top and get smaller row by row - called a Snellen scale. There are many tests of visual acuity. One of the more common is the Snellen test type. This is made up of many letters of different size. By conventions the chart is placed 6 metres away from the patient. Each eye is assessed with two numbers, such as having 6/6 vision. The first number is the distance the chart is viewed from. The second is the distance at which the person being tested can see a letter clearly. If they are only able to see the top letter they have 6/60 vision. ‘Normal’ vision is 6/6.
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Thanks for your intrest