What Does It Mean to Have 20/20 Vision?

Having 20/20 vision means you can see objects clearly from a distance of 20 feet. It's a measurement of the clarity and sharpness of your vision. If you have 20/20 vision, you have a clear view of things that are 20 feet away from you.

What 20/20 Vision Means

A measurement of 20/20 vision refers to visual acuity. Visual acuity describes a person’s ability to see shapes and details. It is not the full measure of vision but rather a factor that is taken into consideration when judging a person’s ability to see.

Eye Health

Your vision is processed through various parts of the eye, including:

• Retina: The retina is a layer of tissue at the back of the eye that is responsible for transforming light into electrical signals.
• Lens: Located behind the pupil and iris, the lens focuses light onto the retina. It helps you see images clearly.
• Optic nerve: The optic nerve connects the retina and the brain and transmits electrical signals to the brain so it can form images.
• Pupil: The pupil is the black dot in the eye that can expand and shrink depending on how much light it is exposed to.
• Iris: The iris is the colored part of the eye. It’s the muscle that controls the pupil, and it controls how much light enters the eye.
• Cornea: The cornea is the layer at the front of the eye. It is shaped like a dome and bends light as it enters.

All the components of the eye work together to interpret and transform light into electrical signals that allow the brain to create the images that you see.

Measurements of eyesight do not determine how healthy your eyes are. Therefore, even if you have 20/20 vision, you could still have unhealthy eyes. A vision test will also not be able to determine whether you have an eye disease.  

How Is 20/20 Vision Measured?

Several exams can be used to measure visual acuity, including the following:

• Snellen charts, or the Snellen system of visual acuity, are the most common tools for testing vision in the United States. The Snellen test uses a printed chart that has rows of letters that decrease in size from top to bottom. During this exam, the chart is set 20 feet away, either physically or through the use of mirrors or an adjustment in the size of the letters. You will be asked to read the letters or numbers (called optotypes) of each row aloud, starting from the top and largest letter.
• Tumbling "E" charts are used for those who can’t or don't wish to speak, as well as for people who can't read or when there is a language barrier. The entire chart is made up of rows containing the letter "E" facing in different directions. The person tested points in the direction that the "E" is facing to let the clinician know they can see it clearly.
• LEA Symbols vision charts are used as an acuity test for children who are not old enough to read letters. The letters are replaced with symbols or pictures, such as an apple, a square, or a circle.
• Jaeger cards, or Jaeger eye charts, used for near vision, are cards on which paragraphs of text are printed, with the text sizes increasing from top to bottom.
• Feinbloom flip-books and ETDRS charts (Early Treatment Diabetic Retinopathy Study charts) may also be used to examine someone who has low vision or visual impairment.

Is 20/20 Vision Perfect Vision?

Many people believe that 20/20 vision means that they have perfect vision, but that is not the case. Other factors determine how well you can see, including:

• Eye focus: Eye focus is the measurement of how well the lens in the eye adjusts to see things clearly regardless of how close or far away they are.
• Eye coordination: This describes how well the eyes work together. Since the eyes are located apart from one another, the images they see are slightly different. The brain fuses those images together to form one and that fusion process is aided by eye coordination.
• Eye teaming, or binocular vision: Eye teaming plays a role in depth perception.
• Eye movement: This is involved in tracking and acquiring images.
• Visual perceptual skills: They are used to help organize and interpret visual stimuli.
• Color vision: Color vision is the colors we see based on the eye’s ability to distinguish between light waves.

The entire picture involves all these different parts. They help determine how good your vision really is.

Farsightedness

Hyperopia, also referred to as farsightedness, is when a person cannot see objects that are close to them clearly. The vision of people with this condition is typically normal when looking at things far away from them.

People with farsightedness have to put more effort into seeing clearly and focusing on objects close to them. This can lead to a variety of problems, such as eye strain, headaches, fatigue, sporadic double vision or blurred vision, and worsening farsightedness.

The typical 20/20 test does not adequately address vision in those with farsightedness. This is because the distance between a person and the eye chart is better for finding out if someone is nearsighted, or has trouble seeing things that are far away from them. That means that a person with farsightedness can have 20/20 vision or remain undiagnosed for long periods of time.

What If I Do Not Score 20/20?

Not scoring 20/20 on a vision test isn’t always a cause for concern. It just means you see less clearly at 20 feet away than people with 20/20 vision.

Nearsightedness, also called myopia, is a risk factor for glaucoma, cataracts, and retinal detachment, so it's important to have an eye exam to rule these eye diseases out and not just a vision test.

There are varying degrees of vision acuity aside from 20/20:

• 20/30 to 20/60: Mild vision loss
• 20/70 to 20/160: Moderate low vision
• 20/200 or worse: Severe low vision
• 20/500 to 20/1000: Profound low vision
• Less than 20/1000: Near-total low vision
• No light perception: Total blindness

Vision with the readings above is best corrected with glasses. If someone only sees 20/200 with their glasses, then they have severe low vision. However, people who see 20/200 and are able to wear glasses to see 20/20 are not considered visually impaired.

If you don’t score 20/20 on your test, it could also be because you have scored higher. It’s possible to have better than 20/20 vision. Some people have vision as high as 20/10.

Frequently Asked Questions

Does 20/20 vision mean you have perfect eyesight?

Perfect eyesight is often confused with 20/20 vision. To determine perfect eyesight, visual acuity must be taken into consideration, along with various other sight factors, such as the ability to see color, depth perception, and peripheral vision.

Is there such a thing as better than 20/20 vision?

It is possible to have better than 20/20 vision. Some people may have a visual acuity of 20/10, which means they can see the same amount of detail from just 20 feet away as a typical person can see at only 10 feet.

Where did the term "20/20 vision" come from?

The 20/20 measurement system was developed by the Dutch ophthalmologist Herman Snellen in 1862. The fraction 20/20, along with other fractions of visual acuity, such as 20/40 and 20/60, are known as the Snellen fractions. If you have 20/20 vision, you can see objects clearly at 20 feet that should be seen clearly at this same distance.

Summary

Having 20/20 vision means you can see objects very clearly from 20 feet away. It's one way to measure visual acuity, which is how clearly you can see things. However, overall eye health also takes into account other factors, such as color and depth perception.

You can also have 20/20 vision and still have an eye disease. It's important to have a comprehensive eye exam and not just a vision test to determine eye health.

A Word From Verywell

Having 20/20 vision is a good thing when it comes to seeing objects at a certain distance, but it does not mean that you have perfect vision and don't have an eye condition. Not having 20/20 vision is often not something to worry about either, because it just means you can't see as well as others from 20 feet away or that you may have nearsightedness.

Nearsightedness, or myopia, is the ability to see objects up close clearly, while objects farther away are blurry. It is easily corrected with prescription lenses. The best way to determine the health of your eyes is to get a proper eye examination that can measure the different facets of your eye health.