Skip to main content

website banner

Request an Appointment
Menu
Home » Private: Eye Exam Q&A » 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!

stouffvillecovid

Dear Valued Patients, 

As per Ministry guidelines and the direction of the College of Optometrists in Ontario, our office is open by appointment only for all your vision care needs. We have taken extensive measures to keep our team and patients safe. We have implemented a locked door policy, temperature and oxygen check upon arrival, increased sanitization measures, and porch pick-up service.

We ask that if you or someone you live with has been ill in the last 14 days, traveled outside of Canada in the last 14 days or have been diagnosed or exposed to Covid 19 in the last 30 days or if you or anyone in your household is waiting for the results of a Covid 19 test that you refrain from entering our practice or booking an appointment at this time.

Thank you for understanding.

Be safe, be well.

x

We are hiring!
Click HERE.