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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!

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Dear Patients,

Ontario will be entering LOCKDOWN on December 26 @12:01AM by order of the Government of Ontario for at least 28 days. Please note that medical care including Optometry services are NOT impacted by these changes.

We will continue to operate following Public Health protocols including screening, PPE, handwashing & sanitizing as well as maintaining physical distancing where possible.

We are open throughout the holiday season (Closed Dec25-27 and Dec31-Jan3) for orders, with very limited in person care. We will be open for full care on Jan 4. We will reserve two urgent care appointments each day during the province-wide lockdown to help reduce the number of eye related emergency room visits for our current patients.

If you are experiencing an eye emergency (loss of vision, double vision, distortion to vision, ocular pain, photosensitivity or other visual symptoms) please contact the office at 519 822 2710 for advice before presenting to the emergency room.