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What Does It Mean To Have 20/20 Vision?

One of the most common terms associated with optometry and eye exams is probably the term “20/20”. This term is so well recognized, that there are even popular phrases with it used outside of optometry. Such as, “hindsight is 20/20”! But what does it actually mean to have 20/20 vision? For most people, this term probably doesn’t mean a lot, other than the fact that it is associated with having “perfect vision”.  But the number 20/20 does actually mean something. 20/20 is a unit of measurement used in optometry and the optical industry to asses vision. Our blog this week is dedicated to “20/20” to explain just in fact what it means and how it works!

Understanding The Eye Test

If you’ve had an eye exam, you are then familiar with the “eye chart”. The eye chart (Snellen Chart – proper name) is an important part of an eye exam! The ability and clarity in which a patient is able to see the Snellen chart helps the optometrist assess the patient’s vision. When measuring visual acuity (just how well a person sees) your optometrist uses a unit of measurement (like the numbers 20/20, 20/10, 20/50 etc) to determine how well and individual sees. The first number denotes the distance that you are standing from the Snellen chart. And the second number, is the distance that a person with normal vision can see and read the same line on the chart.

What Does 20/20 Vision Mean?

So knowing now that 20/20 is a unit of measurement, we can understand what 20/20 means.  If we can read the chart at 20 feet away (1st number) and most other people can also read the same chart at 20 feet away (2nd number). 20/20 vision means that vision is “normal”.

What If You Don’t Have 20/20 Vision?

For people who have a hard time reading the eye chart, the second number will be higher then the first number. For example, if a person as 20/50 vision, it means that they have to be standing 20 feet away from the chart to read it, where most other people with normal vision can read the same chart, standing farther away at 50 feet. So basically the measurement means that you have vision which is worse than average and by about how much.

You can also have vision that is better than 20/20 as well. For example, if a person has 20/10 vision, it means that they can again read the eye chart at 20 feet away, while most other people can only see the same line on the eye chart when they are standing closet at 10 feet.

Having 20/20 Vision

If you don’t have 20/20 vision or better, the goal of your optometrist is to get your eyes seeing as close to 20/20 vision as possible. They do this with the help of vision correction aids such as glasses or contact lenses. Sometimes there are eye problems or diseases which will prevent a person from seeing 20/20 no matter what correction they wear.

A person is “legally blind” if their corrected vision (with eyeglasses or contacts) is 20/200 or worse.

A Vision Test Is Only Part Of Your Exam

Even though it is nice to know what your vision is, such as 20/20. Or have your vision corrected to 20/20 with the help of glasses. 20/20 doesn’t mean that your eyes are healthy. The measurement is just one tool that the optometrist uses to assess your eye health and vision. Many eye conditions have no symptoms or symptoms which progress slowly over time. This can make it hard for a person to acknowledge that their vision is deteriorating. Because of this, if it important to have both your vision and eye health assessed regulaly during routine eye exams. Occasionally it is only during an eye exam that problems can be detected.

 

 

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