We have all heard people refer to their sight as perfect if they have 20/20 vision, but what does it actually mean? You may have also heard about 6/6 vision. The only difference is depending if you are in the UK or America, as it is measured in either feet or metres. 6/6 vision describes being able to see at 6 metres what an average person can see at 6 metres. While 20/20 vision describes the same ability, but at 20 feet rather than 6 metres.
Comparatively, if you have 6/12 vision for example, what you can see at 6 metres away, an average person can see from 12 metres away and you therefore have below average vision.
While 20/20 is more widely used in everyday speak, in the UK we say 6/6 vision.
How is Vision Measured?
The Snellen Chart was developed in 1862 by Herman Snellen, a Dutch ophthalmologist. It is used to measure people’s visual acuity, to assist with assigning the correct glasses and contact lens prescriptions.
During an eye examination, you will be asked to read each line of letters on the Snellen Chart. Each line gives an idea on your visual acuity. In addition to building your glasses prescription, eye tests are sometimes required for certain tasks or jobs. For example, in the UK, you can legally drive if you are able to read a number plate from 20 metres and that your eye test presents a visual acuity of 6/12 at the minimum. Drivers are allowed to wear spectacles or contact lenses when performing this task.
Knowing What Your Glasses Prescription Means
If you do require a prescription from your optician, it is good to have an understanding of what it means.
Your eye prescription is measured in dioptres, which measures refractive errors. If your prescription has negative numbers (-), that means you are short sighted, while positive numbers (+) represent long sightedness.
For example, -1.00 on your eye prescription means that you have one diopter of nearsightedness, which is mild, whereas, a note of -3.75 means 3 and ¾ diopters. This is a stronger case of nearsightedness, so your optician will prescribe you stronger lenses.
Alternatively, a note of +1.00 on your prescription will mean a smaller amount of farsightedness compared to +5.
When to Book an Eye Test
To ensure that your eye health is in check and that you have an up to date glasses prescription, book an eye test with our team at Dominic Tunnell Opticians. Using the latest technology and most professional staff, we offer quality eye exams and first class care for your eye sight.
To book an eye test, simply call 01905 950267 today.