Being told by the Optometrist that you have 20:20 vision is something that fills most people with pride but is it really that big an achievement and what does it actually mean? The first thing to say is that although people consider 20:20 vision to be perfect vision, it actually only equates to what the average adult should be able to see. A large percentage of people attending the Optometrist will have 20:20 vision and it is what the Optometrist expects you to be able to see. As to what 20:20 vision means, you can read the following simple explanation:
- The first number: The first number represents the distance from which you are looking at the letter. In the case of 20:20, the distance is 20 feet, which is the standard distance which Optometrists testing rooms are set up for. You may think that 20 feet seems a little too large for an Optometrists room but take into account the mirror you look into which doubles the size of the test room.
- The second number: The second number represents the size of the letter you are looking at. So effectively, what 20:20 vision means is that you can see a size 20 letter at 20 feet away. The higher up the test chart you go the size of the letters increases. The very top letter (the biggest) is the number 200 letter. If you are only able to see this size of letter then your vision is said to be 20:200.
What does better than 20:20 vision mean?
If you imagine you are looking at the eye test chart in an Optometrists, the bottom line of the chart is actually smaller than the 20:20 line. On most eye tests charts (this varies) the 20:20 vision line is actually the third line up from the bottom. This effectively means that there are 2 rows of letters that are smaller than this line. The line directly below that 20:20 vision line is normally 20:15 and the very bottom line is normally 20:12. This means that at 20 feet you can successfully see size 15 and size 12 letters respectively.
What happens if I don’t have 20:20 vision?
For those people that do not have 20:20 vision you are likely to need to wear glasses, contact lenses or have laser eye surgery. Just because you don’t have 20:20 vision without glasses does not mean that you won’t be able to achieve 20:20 vision or better with a visual correction. For most people glasses, contact lenses or laser eye surgery will improve their vision to 20:15 or even 20:12. It is generally only if you have an eye disease or lazy eye that you will not be able to achieve 20:20 vision. The reason for this is because the eye disease has damaged your eyes to such an extent that even with the best possible glasses on you are still unable to achieve 20:20 vision.
In summary, whilst 20:20 vision is something to be thankful for, it is only what the average person is expected to see. Most people should expect to see even better than this and this is something you can ask your Optometrist the next time you attend for an appointment. The next time you hear someone being smug about their 20:20 vision, you will be able to confidently point out to them that it is not nearly as impressive as they think it is!
This article was written by an Optometrist from the UK, where the equivalent of 20:20 vision is 6:6 vision. This means a size 6 letter at 6 metres, rather than 6 feet. Tim also writes for his own website Treatmentsaver.com which covers topics ranging from Botox cost to Glaucoma. Tim’s number one piece of advice to anyone reading this post is to ensure that you have an eye test at least every 2 years.