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Optometrist At Holly & Derry in Milton, ON

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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!

Dear Patients,

Today, under directions from the College of Optometrists of Ontario, we have made the difficult decision to immediately suspend all non-urgent care,  due to the COVID-19 pandemic. Our doctors will still be accessible for ocular emergency assessments case by case. The clinic is closed.

All non-urgent appointments will be canceled and rescheduled for a later date. For urgent care please DO NOT call or come to the clinic, but send an email to: info@miltoneyecare.ca for appropriate triaging.

For patients who need to order contact lenses, please continue to place your order request on our website at www.miltoneyecare.ca. We encourage a 6-12 months’ supply of contact lenses to be ordered.

What consists of an emergency: Ocular Emergencies require an urgent visit within 24-48 hours. Please email our office should you experience:

  1. Chemicals splashed into the eye within the last hour
  2. Sudden loss or decrease in vision, or the appearance of a cloudy veil in front of the eye
  3. Foreign body in the eye, ocular injury or forceful trauma to the eye or surrounding area
  4. Sudden onset of halos around lights; especially if associated with a red painful eye or brow
  5. Sudden onset of flashing lights or floaters
  6. Sudden onset of double vision
  7. Red eyes with pain, light sensitivity or pus discharge
  8. Swelling of eyelid

If you are not sure if you are experiencing an ocular emergency please email our office at info@miltoneyecare.ca

 As this situation evolves, Milton Eye Care is committed to providing updates to our patients. While this is a difficult time for all, we are aspired by our patients who have taken their own personal measures to protect our most vulnerable. Thank you for your understanding. Please stay safe and healthy.

Warmest regards,

Milton Eye Care team