The Myth of 20/20 Vision

Published on
February 24, 2022

20/20 vision means that you can see a small letter or letters from 20 feet away, with your best correction in place whether it's glasses or contact lenses. Most patients come in and think their eyes are doing well if they can see 20/20. 20/20 is an important component of an eye examination, but it does not explain everything about our eyes. 

 

Can I get an Online Eye Exam? 

The myth of 20/20 vision lends itself to the discussion of an online eye exam. While the technology exists to virtually give a person a prescription for glasses or contact lenses, the technology does not exist to test the full scope of ocular health and function that is done during a comprehensive eye exam. According to the disclaimer at the bottom of the page on all of the online eye exams they state:

“An eye health exam cannot be replaced by a virtual vision test, and it does not represent a comprehensive eye examination. It’s important to get your eye health examined periodically even if you aren’t experiencing any vision problems, so please follow the advice of your doctor.”

 

What is Assessed During a Functional Vision Exam?

The eye's function goes much further than simply being able to see clearly. Whenever an eye doctor examines the function of the eye, they are usually interested in more than just the health of the structures in the back of the eye, how the eye sees at a static distance, and how the pupils react. A vision of 20/20 is by no means the end all be all of good vision and certainly not of good functional vision.

During a functional eye exam the eye doctor is looking at all things related to how we see the world in our day to day functioning. This means that the functional optometrist is no longer just looking at the eye itself, but also examining the eye-brain relationship as well as the processing of visual information. 

When examining the patients ability to use their vision to function, the functional optometrist will assess: 

Functional Visual Acuity: meaning the ability to see at near (reading), far (looking at the board), and mid distance (using a computer or watching the television). 

Visual Field: How much of the world we see in our field of vision or in our peripheral vision. 

Oculomotor Function: How our eyes are able to move, for example reading requires the ability to smoothly scan or track both eyes across a sentence. 

Visual Perception: How we process the visual information that we take in, for example how we understand what we read or how we understand material that is presented visually. 

Accommodation: The ability to focus on an object, for example when a student copies text from the board they need to shift their focus from near to far and back. 

Binocular Vision: The ability to form one image clearly from the individual visual information gathered by each of our two eyes, for example someone who has binocular vision issues may only see an image from one eye and lose depth perception. 

Contrast Sensitivity: The ability to discern differences between shades of color or patterns. Someone with poor contrast may have difficulty reading or walking around without tripping. 

Color Vision: Approximately 8% of males have some amount of color blindness which can make certain learning situations difficult. 

 

What does 20/20 vision mean for you?

It is likely that you do not need glasses, contact lenses, or magnifiers if you have 20/20 vision. In the event that you are nearsighted (able to see things clearly up close), farsighted (able to see things in the distance clearly), or you are a combination of the two, you are likely to need corrective lenses. Even if you don't need glasses, it is important to understand that your total vision cannot be determined by how well you read the E chart.

 

How do you know when you have a vision problem if 20/20 isn't a true indicator of your eyesight?

 

School Eye Testing

Vision screenings conducted by schools are not the end-all and be-all of vision screening, but they can give you a good indication as to how well your child sees and whether they need help. It is crucial to understand that these screenings cannot detect a wide range of vision problems, which is why using them to prove that someone has "perfect vision" is inadvisable. As per the College of Optometrists in Vision Development (COVD), the most common visual problems are not related to visual acuity. And according to the American Optometric Association a school vision screening only assesses 4% of a comprehensive eye exam. 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

We recommend a functional eye exam (also called a developmental eye exam) for all children as they enter school. For older children and adults, a functional vision exam is important if you are experiencing blurred vision, headaches, neck strain, dizziness, difficulty recalling, reading comprehension, or other significant visual problems.

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