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A Snellen chart is an eye chart that can be used to measure visual acuity by reading letters of different sizes. The chart is named after Herman Snellen, who developed it in 1862, and is used at a standard distance of 6 metres or 20 feet.
12 Οκτ 2021 · The Snellen chart is an eye chart that measures visual acuity by how well a person can read letters from 20 feet away. Learn how the chart works, how to download a printable version and what it means for your vision.
10 Οκτ 2024 · Most vision testing in the United States uses the Snellen chart, which requires a test distance of 20 feet. In other countries, visual acuity is expressed using the metric system. Because 20 feet is equivalent to 6.096 meters, 20/20 vision is equal to 6/6 vision.
21 Μαρ 2014 · As today’s exam lanes often are smaller than 20 feet (6 meters), charts are often designed for shorter distances. This is no problem for visual acuity measurement, as long as the actual test distance is accurately accounted for. For use in refraction, shorter distances are less desirable.
24 Σεπ 2024 · The first number (20) in a Snellen fraction represents the distance the person being tested is positioned from the chart. The second number represents the distance at which the smallest standardized letters are clearly visible.
1 Μαΐ 2023 · The Snellen Chart uses a geometric scale to measure visual acuity, with normal vision at a distance being set at 20/20. The numerator represents the distance that the patient is standing from the chart (in feet), while the denominator represents the distance from which a person with perfect eyesight is still able to read the smallest line that ...
Learn how to use, hang and interpret the Snellen eye chart, a standard tool to measure visual acuity. Find out how to print or buy a Snellen chart and what it means to have 20/20 or 6/6 vision.
