Top 4 Eye Charts Used During Eye Exams
“Can you please read me the first 2 lines?”
“Umm..sure. E, F, P.”
Most of us have experienced the nerve racking moment when the Optometrist asks you to read the letters off the eye chart. We start to second guess ourselves and how “blind” we are. But just like most things in medicine, there is a method to using the eye charts.
Eye charts are just one of many tools the doctor uses when conducting an eye exam, but they serve a valuable purpose when checking your vision.
Eye charts are used during an eye exam to measure visual acuity by checking how well you see in comparison to other people. Your eye doctor has you look at the eye chart and read the smallest line of text that you can see from 20 feet away. If you see clearly at 20 feet, which is what most people see at that distance, you have 20/20 vision.
In the United States legal blindness is defined as your best corrected vision, even when wearing glasses or contact lenses, is only 20/200. 20/200 vision means you have to get within 20 feet of the eye chart to read the line that people with normal vision can see from 200 feet away.
Top Eye Charts used by Optometrists
Optometrists use eye charts as a basic vision check. Today many variations of the eye chart exist. The four most common eye charts used are:
The original eye chart designed in the 1860’s by the Dutch eye doctor Hermann Snellen. The first line on this chart is a giant letter E. You read the chart from top to bottom, left to right covering one eye at a time.
2. Tumbling E
This type of eye chart is used for children that are too small to read or adults with reading or speaking difficulties. The patient is asked to lift their hand up, down, to the left or right depending on the image orientation of the letter E they see on the chart.
3. Landolt C
Edmund Landolt, a Swiss ophthalmologist, created this visual acuity chart. This eye chart, which is similar to the Tumbling E chart, uses a Landolt broken ring symbol in various orientations. The Landolt C chart is a way to check vision for illiterate or mute patients.
The Early Treatment Diabetic Retinopathy Study helped develop standardization for both visual acuity testing and eye chart design. The ETDRS is accepted by The National Eye Institute and the Food and Drug Administration as the mandated standard for clinical eye test trials worldwide.
Get Your Eye Exam at Stanton Optical
Optometrists are primary healthcare providers and offer eye and vision care services to their patients. A Doctor of Optometry does many different vision tests during a routine eye examination, including the eye chart test.
Besides prescribing corrective eye wear, eye doctors also diagnose common vision problems like cataracts, macular degeneration and diabetic retinopathy.
Schedule your appointment at Stanton Optical today!