The majority of us mistakenly believe that 20/20 on the E chart means everything is fine with our vision when we actually need to use 17 visual skills every single day.

What does 20/20 mean?

The top number 20 refers to the distance between a person and the chart when they are being tested. The bottom number indicates the size of the letters that the individual is able to read on that chart. As distance is measured in feet and inches in the United States, the quantity 20 refers to the number of feet between a patient and the standard E chart an optometrist uses to test visual acuity. In turn, how well you can read numbers and letters on the chart from this distance determines how well you can see clearly. The UK and other countries that are using the metric system refer to 20/20 vision as 6/6 vision, which indicates the distance in meters between patient and chart rather than feet.

Is your vision perfect if you have 20/20 vision?

Therefore, if someone's vision is 20/20, they probably don't need glasses, contact lenses, or any type of magnification to see clearly. It doesn't mean that they don't have any other types of underlying vision problems since their vision may not be perfect. You may need corrective lenses, however, if you are nearsighted (meaning, you see well when things are close up), farsighted (you can see clearly at a distance), or a combination of both. In spite of whether or not you need glasses, it is important to remember that your vision cannot simply be determined by how well you read the E chart.

Learn more about nearsightedness and farsightedness.

If 20/20 is not a true indicator of your vision, how do you know if you have a vision problem?

School Eye Testing

Schools can conduct vision screenings, but they are not the end-all and be-all of vision screening, although they can provide a good indication of a student's vision and the need for help. These tests cannot detect a wide range of vision problems, which is why using them to prove someone has "perfect vision" is not appropriate. According to the College of Optometrists in Vision Development (COVD), the most common visual problems are not related to visual acuity. A school vision screening only accounts for 4% of a comprehensive eye exam, according to the American Optometric Association. In any case, you should take the results of any school vision test to your eye doctor, so they can compare what they see in the office with what was recorded in school.

Eye Function

All children entering school should receive a functional eye exam (also known as a developmental eye exam). A functional vision exam is important for older children and adults who have blurred vision, headaches, neck strain, dizziness, difficulty recalling, reading comprehension, or other significant visual problems.