10 doctors weighed in:
What do the big and small letters mean on an eye vision chart?
10 doctors weighed in

Dr. Andrew Shatz
Ophthalmology
5 doctors agree
In brief: Average vision
The eye chart compares your ability to see a specific size object at a determined distance (usually 20 feet) to the average person.
If you can read the small letters at the 20/20 line, it means that you can see an object at 20 feet as well as the average person. If you have 20/30, it means that you have to be 20 feet from an object to see it when the average person can see it from 30 feet away.

In brief: Average vision
The eye chart compares your ability to see a specific size object at a determined distance (usually 20 feet) to the average person.
If you can read the small letters at the 20/20 line, it means that you can see an object at 20 feet as well as the average person. If you have 20/30, it means that you have to be 20 feet from an object to see it when the average person can see it from 30 feet away.
Dr. Andrew Shatz
Dr. Andrew Shatz
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1 comment
Dr. Mark Sibley
Another way to understand these funny fractions is to understand eye doctors...(Not always easy)...We measure vision that our patient sees at 20 feet- the top number...20/x..The bottom number is the size of the letter that the patient sees at 20 feet.If it is the small size "20" letter then we say-20/20...If only the large "400" E is seen then we say 20/400.. So, what was your vision ??
David Miller
Family Medicine
3 doctors agree
In brief: No hidden meaning
The letters themselves aren't really the important thing-eye charts have different letters (or even shapes).
The point of them is that you stand a specific distance from the chart & read what you can. The lowest line you can read tells you the "strength" of your vision, based on the numbers at the end of each line. This is a good screen, but not a replacement for regular eye doctor appointments.

In brief: No hidden meaning
The letters themselves aren't really the important thing-eye charts have different letters (or even shapes).
The point of them is that you stand a specific distance from the chart & read what you can. The lowest line you can read tells you the "strength" of your vision, based on the numbers at the end of each line. This is a good screen, but not a replacement for regular eye doctor appointments.
David Miller
David Miller
Answer assisted by David Miller, Medical Student
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