When people learn they have “20/20 vision,” they tend to think this means they have perfect eyesight. And while they may not need glasses or contacts to see things at a distance, people with 20/20 vision can certainly still have eyesight problems.
What Does 20/20 Vision Mean?
If you can read the 20/20 line on an eye chart from 20 feet away, you can see what others with good visual acuity can see at this distance. This simple test reveals if you have sharp distance vision, but it doesn’t tell you anything else about your eye health.
The Snellen Chart
The eye chart in your optometrist’s office with the big letter E at the top is called a Snellen chart, named for Dutch ophthalmologist Herman Snellen, who developed it in 1862. He also defined “standard vision” as 20/20, which is why visual acuity measurements are known as Snellen fractions.
Is There Anything Better Than 20/20 Vision?
Seeing 20/20 may be the goal, but it’s not the best vision you can have. After all, there are letters below the 20/20 line on a Snellen chart. If you can see these letters from 20 feet away, you have 20/15 vision. And if you can see the line below that, you have 20/10 vision.
Snellen fractions can also go the other way. For instance, if you have to get within 20 feet to see what someone with normal vision can read from 30 feet back, you have 20/30 vision. And if you can only make out the large E at the top, you have 20/200 vision.
What Keeps People from Seeing Clearly?
Refractive errors are common eye disorders that affect visual acuity at different distances. There are four main types:
- Nearsightedness (myopia) makes far-away objects look blurry. Eye charts are good at measuring this.
- Farsightedness (hyperopia) makes up-close objects look blurry. Someone with 20/20 vision could still be farsighted.
- Presbyopia makes up-close objects look progressively blurrier as the years go by. This is a natural part of aging.
- Astigmatism makes objects both near and far look blurry or distorted.
What Else Contributes to Good Vision?
Other important visual skills are needed to see clearly besides visual acuity. These include:
- Peripheral awareness
- Eye coordination
- Focusing ability
- Depth perception
- Color vision
- Ability to track moving objects
- Ability to discern objects similar in brightness to their background
Who Needs Eye Exams?
Everyone should schedule an eye exam once a year, whether you have trouble seeing far-away objects, can’t focus on things up close, or think you have perfect vision. These visits are important for checking your eye health, monitoring any eyesight changes, and diagnosing diseases like glaucoma and cataracts.
Denver Eye Surgeons is your source for quality vision care in Denver, CO. We can examine your eyes, prescribe corrective lenses, and offer advanced treatments to help you achieve and maintain clear vision. Feel free to contact us with any questions you have, or request an appointment online today.