So you’ve taken an eye test and your results came back an exciting 20/20. Or maybe you’ve got a friend who’s always bragging about their “eagle eyesight”. Or perhaps you’re just curious about the “ideal” vision score. Well as it turns out, there is more to the concept of 20/20 vision than meets the eye.

Eyesight ratios

Nearly two hundred years ago, the field of optometry made a concerted effort to standardize methods of determining a person’s overall eyesight. This is how we got what is called the Snellen ratio (named for the doctor who created it). This is the eye chart that we’ve all seen hanging in the doctor’s office. By standing an appropriate distance from the chart and reading off each consecutive line, you’re giving the eye doctor all the tools they need to calculate your vision acuity.

Your vision ratio will always start with the number 20. Put simply, the first number represents you, and the second represents the “average” person who does not need glasses. So 20/20 vision means you can see at 20 feet what the average person with healthy vision can also see at 20 feet. If you had 20/15 vision that would mean you can see at 20 feet what the average person can only see at 15 feet. 20/35 would be the opposite, meaning you can’t see past 20 feet what the average person could see at 35. The lower the number on the right, the better your vision is and the lower your odds of needing eyeglasses.

20/20 is not perfect

It is a misconception that 20/20 vision is perfect or the strongest eyesight possible. What 20/20 vision is considered to be is normal vision. It is by far not the best eyesight out there.

Even with 20/20 vision or close to it, some people may still need prescription glasses. Having 20/20 vision isn’t automatically a clean bill of eye health. There are many eye conditions and problems that manifest in other ways. So just because you can read that eye chart from across the room doesn’t mean you should let your eye exams fall to the wayside. A comprehensive eye exam is the only way to catch problems with the perception of contrast, color, peripherals and much more. Everyone should visit the eye doctor every one to two years, especially children.

Once you have an updated prescription from an optometrist, you can order online glasses and contact lenses to save time and money. Prescription glasses from are UV-resistant and come with anti-glare coating.