Having 20/20 vision describes a person’s ability to see shapes and details, known as visual acuity, from a distance of 20 feet away. Visual acuity is only one component of determining eye health, so having 20/20 vision doesn’t always indicate perfect eye health.

What Factors Determine Eye Health?

There are several parts of the eye that play an important role in vision, such as the retina, lens, pupil, optic nerve, iris and the cornea. Together, they interpret light as electrical signals that the brain will make sense of and create images that can be seen.

To ensure the eye is working correctly, several factors must be taken into consideration when determining eye health, such as:

• The Eye’s Ability to Focus: This is a measurement of how well the eye lens adjusts to see clearly regardless of distance.
• The Eye’s Ability to Coordinate: This is a measurement of both eyes’ ability to work together. The brain can fuse the images that each respective eye sees to form one image.
• Eye Teaming Binocular Vision): This is important for measuring depth perception, which is the ability to see the distance between objects.
• Eye Movement: This allows the eyes to both find and acquire images.
• Visual Perceptual Skills: These skills involve organizing and interpreting visual stimuli.
• Color Vision: This measure’s the eye’s ability to distinguish between light waves, which create color.

These factors together allow the eyes to form an entire picture.

What Do Vision Scores Mean?

If you do not score 20/20 on a vision test, it may simply mean you see less clearly at 20 feet away. 

The degrees of vision acuity aside from 20/20 may include:

• 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 Perception of Light: Complete Blindness

Some people may even score 20/10, which means they can see the same amount of detail from just 20 feet away that most people would only be able to see 10 feet away.

Common Vision Problems

The degrees of visual acuity can be coupled with other vision problems. Farsightedness, for example, is the condition of not being able to see close objects clearly. This can lead to several issues, such as eye strain, headaches, fatigue, sporadic double vision or blurred vision.  However, a person may be undiagnosed for a long period of time since eye charts are better at helping to determine nearsightedness, which is when someone is only able to see things that are close to them (versus far away). 

Nearsightedness is a risk factor for glaucoma, cataracts and retinal detachment, which can be found on eye exams. Undiagnosed eye problems may lead to a lack of focus and concentration in students and an attention deficit hyperactivity disorder (ADHD) diagnosis.

For these reasons and more, a comprehensive eye exam, in addition to a vision test, is necessary for determining one’s eye health as it allows doctors to catch eye disease before it develops and progresses. A comprehensive exam will look at factors like visual acuity, the ability to focus and coordinate, color vision, and more, as all are critical parts of holistic eye health.

*Bottaro, A. (2021, July 30). Does 20/20 vision really mean you have perfect vision? Verywell Health. https://www.verywellhealth.com/20-20-5187978