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Home » Your Eye Health » Eye Exams » Common Tests » Snellen Chart

Snellen Chart

Hopefully by now, we’ve all seen one. The projected or wall-mounted Snellen eye chart, usually topped by the big letter “E”, is a common visual acuity test used to measure your sharpness of vision at multiple distances.
 
Arranged as a pyramid of sorts, the letters in the Snellen chart are specifically chosen and arranged to test your sharpness and clarity of vision at a baseline distance of 20 feet. During a visual acuity test, the Snellen eye chart is viewed as a projection, or mounted on a wall.
 
Handheld versions of Snellen charts are used for testing near vision as well.
 
By viewing or reading each line from top to bottom (with one eye covered at a time), your eye doctor can gain a general approximation of the quality of your visual acuity, or sharpness. Where a line of characters begin to become difficult to see is the approximate measurement of your vision.
 
The Snellen chart serves as a beginning—not an end—to a comprehensive eye examination.

What does “20/20” vision mean?

Snellen charts help to determine a baseline for your vision in each eye—a baseline typically measured against “20/20” vision. This means when you are 20 feet away from an object, you can comfortably see details that most people with normal vision can also see at 20 feet distance.
 
If you have 20/30 vision, that means what you see comfortably at 20 feet, can be seen by a person with “normal” vision at 30 feet. Your vision is weaker, in other words.
 
Conversely? In the rare instances where vision may test better than normal on a Snellen chart, a value of 20/10 vision means that you can see clearly from a distance of 20 feet, what a person with normal vision sees well at a distance of 10 feet. Make sense?
 
In fact, if you look closely at a Snellen eye chart, you’ll see the vision values associated with measuring your vision on the right or left side of each line of characters.
 

Special thanks to the EyeGlass Guide, for informational material that aided in the creation of this website. Visit the EyeGlass Guide today!

COVID-19 Update

Your health and well-being is our top priority at Focusing on Eye Care. In following recommendations provided by the CDC, we have implemented protocols at our office in order to continue to protect the health of our patients and our team.

Every patient and their guest will be asked to fill out a COVID-19 questionnaire. Should you or a guest have flu-like symptoms, fever, exposure to a known person with COVID-19 or have tested positive for COVID-19, you will be asked to reschedule your appointment for a later date until you are well or clear of any potential illness for a minimum of 14 days.

We ask that patients please come to their appointment unaccompanied. If you are requiring a guest to accompany you, we are limiting the number of guests in our facilities to 1 per patient, and we ask that you only bring a guest with you if it is absolutely necessary to avoid crowding in the office.

In addition, we are requiring all employees, patients, and their guests to wear face coverings while in our facilities at all times.

Thank you for all your cooperation as we continue to help you with your eye care needs and for helping us reduce the spread of COVID-19.

Stay Well,

Focusing on Eye Care