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What Does 20/20 Vision Mean?

One of the first phrases that comes to mind when people think about eyesight is “20/20 vision.”

We’ve heard since we were children sitting in the school nurse’s office waiting for our turn looking at the big E chart that 20/20 vision is the best, but what does it mean?

The Snellen Chart

Dr. Herman Snellen, a Dutch eye doctor born in 1834, created the Snellen chart; which is the formal name of that big E chart we all know and love. Before the Snellen chart, there was no standardized method of determining a person’s visual acuity, because different eye doctors would use their own charts. The chart Snellen made revolutionized optometry, and optometrists everywhere still use versions of it today!

The Snellen Ratio

Each line on the Snellen chart is 25 percent smaller than the one above it and represents what someone with normal vision would be able to see at a certain distance. Having 20/20 vision means you can see the same amount of detail at 20 feet as the average person who doesn’t need corrective lenses.

If you have 20/10 vision, it means you can see at 20 feet what the average person has to be twice as close to see.  If you have 20/40 vision, it means you have to be twice as close to something as the average person in order to see it. So if your vision is better than 20/20, enjoy your minor superpower! If it’s worse than 20/20, it’s time to find a stylish pair of glasses!

Schedule Your Eye Exam Today!

The Snellen chart also can’t measure overall eye health, which makes eye exams even more important.

If you haven’t had an eye exam in a while, don’t wait to schedule your next appointment. We look forward to seeing you — and to helping you see more clearly!