How Much Do You Really Know About Eye Charts?

It’s found in every optometrist’s office, family doctor’s office, and even in schools. It’s the eye chart. As the central part of any eye exam, this chart helps your doctor test your visual acuity and determine whether you need corrective lenses in order to see clearly. But what exactly is this ubiquitous chart’s history, and how did it come to be the standard tool used to check how well people can see?

I Go By The Name of Snellen

Like credit scores and carbonated beverages, there are multiple generic versions of things we’ve grown to associate with a specific brand. There may be several credit scores on the market, but the only one that really matters is your FICO score. There may be a cheaper soda at the corner store, but your family only drinks Pepsi. In the world of eye exams and eye charts, the Snellen chart is the most popularly known version.

Developed in 1862 by a Dutch ophthalmologist named Herman Snellen, the Snellen chart is recognizable by its display in doctor’s offices, on TV, and in movies. Letters are printed in decreasing size, and visual acuity is determined based on the smallest line a person can accurately read. The typography on a Snellen chart is very specific as well. Each letter’s line thickness is equal to the white space that separates them from the letters before and after. Additionally, the width and height of each letter is 5 times the thickness of the line of each letter.

Snellen, You’ve Got Competition in the Name of LogMAR

While the Snellen chart has dominated as the de facto chart used in eye exams for decades, it has competition in the form of the LogMAR chart. Developed in 1976, the LogMAR chart is considered a much more accurate and effective way of determining visual acuity, and its use during eye exams in medical and research settings is highly recommended. The Snellen chart paved the way for standardization in eye exams and assessing visual acuity. The LogMAR chart has taken things a step further by working to standardize more variables related to the chart’s composition including size range and the number of characters in each row.

The Work Put Into Improving Charts Underscores the Importance of Eye Exams

To the casual observer, working on finding the perfect typography or establishing the appropriate width between letters in an eye chart may sound obsessive. On the contrary, it is vital for ensuring our methods for testing visual acuity during eye exams are as standardized and precise as possible.

And this is just how seriously eye care professionals take their job of ensuring you see clearly, let alone that your eyes are healthy. Eye exams do more than determine whether you need glasses. Eye exams help you keep your eyes as healthy as possible and avoid more severe issues.

At Eye Associates of Tallahassee our business is eye care and eye health. That’s why we encourage everyone to come in for regular eye exams to keep their vision in perfect shape. Pick up the phone and book an appointment at our Tallahassee, Florida location today.

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