Exploring the Snellen Eye Chart

If you have ever been in the office of an optometrist, then you have likely seen a Snellen eye chart. The Snellen eye chart is the paper that has large letters towards the top that get smaller near the bottom of the paper. Your eye doctor in Miami Beach will use this chart to determine how well you are able to see. If you are told that you have 20/20 vision, then it means that your eyesight is normal in comparison to other people. Having 20/20 vision means that you are able to see an object at the distance of 20 feet as well as most other people can see the same object at the same distance. The chart was invented by an ophthalmologist by the name of Herman Snellen in the year 1862. However, it’s common for an eye doctor in Miami to now use the LogMAR chart, which is an improved version of the Snellen chart.

Information About the Snellen Eye Chart

The eye chart used to determine a person’s visual acuity was originally invented with dingbats, or symbols, instead of using letters. If you ask your Miami Beach eye doctor to tell you more about the Snellen eye chart, you will likely find out some interesting information that you were not aware of.

• The first version of the Snellen chart using dingbats was deemed unsatisfactory because there are people who could see the symbols normally, yet could not describe them effectively. Thus, people with good vision were being told that they may need to wear glasses.
• People used to be prescribed the same lenses as they reached a certain age and experienced vision problems. For example, a 40 year old would get the same glasses as any other 40 year old simply because it was believed that everybody’s vision deteriorated at the same rate. The Snellen chart has helped to dismiss this belief.
• If a person is deemed to have 20/200 vision, then they are considered “legally blind”. However, this doesn’t mean that the person is unable to see anything at all; they can likely still make out shapes, objects, and see certain things–they will just be unable to obtain a driver’s license or legally do certain things that require a specific level of visual acuity.

The Future of Eye Charts and Visual Acuity Tests

Your Miami optometrist is likely going to keep a Snellen eye chart in their office until a more technologically advanced method of testing visual acuity is invented. For example, the LogMAR chart is similar to the Snellen chart in appearance, but it has a different amount of letters and rows on it. This new chart is more accurate in helping doctors determine how well a person is able to see. As time passes and technology progresses, though, a better way to test a person’s visual acuity may arise. If at some point in the next few years your eye doctor asks you to look through a special machine to test your visual acuity instead of looking at a chart on the wall, don’t be surprised!

photo credit: National Eye Institute Snellen Visual Acuity Chart via photopin (license)