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The true meaning of 20/20 Vision

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When most people hear the term 20/20 vision or find out they have 20/20 vision, they understand that to mean that they have perfect vision. They don’t hesitate to share that they have perfect 20/20 vision and do not know what it’s like to have to wear glasses or put on contacts.

We don’t mean to burst their bubble, but 20/20 vision does not mean having  “perfect vision.” When the optometrist says that you have “20/20 vision” he is referring to your visual acuity, which is the clarity or sharpness of your vision. When the doctor tests for 20/20 visual acuity he is testing how well your eyes can see an object at a distance of 20 feet. If you can see the letters clearly, then you are considered to have “normal vision.” This number indicates that you can see objects clearly at a distance of 20 feet, compared to other people.


Optometrist test your visual acuity using the Snellen Eye Chart. The Snellen Eye Chart is used to test visual acuity. It consists of displaying letters of progressively smaller sizes. The common Snellen chart has 11 lines of block letters. The first line consists of one large letter, like the “E” in the image shown below. Depending on the Snellen Chart, the first letter can one of several letters including E,H, and N. As you move down the chart each row not only gets smaller, but also increases in number of letters. The further down you can make it in the chart, the closer you are to having 20/20 vision. The eighth row is 20/20 visual acuity.

The common Snellen eye chart looks like this:

Snellen Eye Chart


Having 20/20 vision may be the goal, and the minimum requirement for pilots, but there are different variations such as:

  • 20/15: This level, is considered superior to 20/20. It means that the patient can see an object at 20 feet that  a patient with 20/20 can only see at 15 feet.
  • 20/40: This is the requirement in order to be able to pass the Driver’s license test in all 50 states. Furthermore, most printed material is set at this level.
  • 20/80: At this level, you should be able to read the time on an alarm clock at 10 feet, and be able to read the headline in a newspaper, as they are set at this size.
  • 20/200: At this level, eyewear is needed. Patients at this level are considered legally blind, and are only able to see the letters on a stop sign.



The visual acuity test is just one aspect of the typical eye exam. Optometrist also test for vision skills such as:

  • Peripheral awareness
  • Eye coordination
  • Depth perception
  • Ability to focus
  • Color vision

Here at Stanton Optical our independent eye care doctor will ensure that you receive An eye exam and receive the appropriate eye care.

Call a Stanton Optical location near you and schedule your appointment today!

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