What is 20/20 vision?

Vision is complicated. The brain, eyes, and vision are connected. So, during an eye exam, your eye doctor will perform different types of vision tests. One test is a visual acuity test to measure your central vision. 

Most of us have heard the term “20/20” vision. When we hear vision referred to as 20/20, we associate it with normal vision, but what exactly does 20/20 vision mean, and how is it measured? The article below will answer these questions. 
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Defining 20/20 vision

The American Academy of Ophthalmology (AAO) defines 20/20 vision as when a person can see an object with sharpness 20 feet away. Experts also consider this to be standard visual acuity. Corrective procedures and glasses aim to achieve 20/20 vision. 

How is 20/20 vision measured? 

Healthcare professionals measure central vision acuity using the Snellen system, named after the ophthalmologist who designed it. The system involves an eye chart with a series of letters of different sizes. 

Most people are familiar with the typical eye chart used. In most cases, the chart has 11 rows of letters. The first line has large letters. Each subsequent row has smaller letters. Usually, you stand 20 feet from the chart. You read the letters with one eye covered, then the other eye, and lastly, with both eyes. 

The chart also has two numbers next to each line. The top number indicates the distance you stand from the chart, and the bottom number refers to the distance at which a person with normal vision can read the line correctly. The Snellen system considers normal eye acuity when a person can correctly read the letters 20 feet away. 
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Does 20/20 vision mean “perfect” vision? 

Having 20/20 vision does not mean a person has perfect vision. Instead, it means a person’s vision is normal. Having 20/20 vision does not consider other factors, such as your depth perception or peripheral vision. 

An eye chart test is also not a comprehensive eye exam. An eye doctor measures other factors in addition to eye acuity. During a comprehensive eye exam, your eye doctor evaluates overall eye health with a variety of tests.
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How often should you have an eye test? 

According to the American Academy of Ophthalmology (AAO), children should have a visual acuity test as soon as they are old enough to read the eye chart. The AAO also recommends adults have a comprehensive baseline eye exam by age 40. Some people who are at an increased risk of eye problems should consider an eye exam sooner. For example, people who have the following conditions should consider having a comprehensive eye exam even before age 40: 

• People with a family history of eye diseases
• Having a personal history of an eye injury or eye surgery
• People with diabetes

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How to maintain good vision

The Centers for Disease Control and Prevention provides several recommendations to decrease your risk of vision loss and promote good vision. Consider the following: 

• Get regular comprehensive eye exams as recommended 
• Learn your family eye health history 
• Avoid or quit smoking
• Eat a well-balanced diet
• Wear sunglasses outside in the sun
• Maintain a healthy weight 
• Manage any medical conditions 
• Wear protective eyewear to prevent injury as needed 

Remember, measuring your vision acuity is a great step in being proactive about your vision. Corrective lenses can help improve acuity. If you have any questions about an eye chart test, we are happy to help. 

Also, if you would like to ask whether an appointment with one of our eye doctors would be appropriate at this time, call our office at 508-746-8600.