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Visual Acuity: What is 20/20?We have all heard of 20/20, supposedly “perfect vision.” But it is actually the measure of NORMAL VISION for the average human eye. The expression is based on comparison of eye’s ability to discriminate a specifically sized object, usually a printed letter, from a distance of 20 feet. 20/20 vision means that the patient can see at 20 feet (the top number) what an average human eye can see at 20 feet (the bottom number). 20/100 vision means that the patient sees at 20 feet what an average eye can see from 100 feet. While this is widely viewed as a measure of a person’s ability to see, it is only a general indication of visual ability. A standard visual acuity score is only way to measure DISTANCE, FORWARD VISION. Furthermore it is influenced by other factors including the patient’s level of fatigue, the lighting conditions and placement of the target in the place that the test is done. A more thorough vision examination by an Optometrist or an Ophthalmologist will include tests that much more accurately measure visual acuity and visual ability.
The familiar Visual Acuity scores are fine for legal, “driver’s license” requirements, but only a small part of your visual comfort. A regularly scheduled, complete eye exam is the only way to be assured of the most accurate vision possible. And, please note that the VISUAL ACUITY score is only truly significant when it is fully corrected. An individual with uncorrected 20/400 can easily be corrected to 20/20 and see much better than an uncorrected 20/30 patient.
The information presented here is intended for informational purposes only. It is not intended to replace medical advice. If you believe you have an eye condition, please contact us at 516-367-2020.
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