Snellen's chart
The familiar eye chart used to measure how well you see at various distances. Snellen's chart is imprinted with block letters that line-by-line decrease in size, corresponding to the distance at which that line of letters is normally visible. The letters on Snellen's chart are, not surprisingly, called Snellen's test type. Each block letter is quite scientific in design (so that at the appropriate distance the letter subtends a visual angle of 5 degrees and each component part subtends an angle of 1 minute). The chart and the letters are named for a 19th-century Dutch ophthalmologist Hermann Snellen (1834-1908) who came up with them as a test of visual acuity. Visual acuity refers to the clarity or clearness of the vision, a measure of how well a person sees. The word "acuity" comes from the Latin "acuitas" = sharpness.

Medical dictionary. 2011.

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  • Chart, Snellen's — The familiar eye chart used to measure how well you see at various distances. Snellen s chart is imprinted with block letters that line by line decrease in size, corresponding to the distance at which that line of letters is normally visible. The …   Medical dictionary

  • Snellen's test type — The letters on the familiar eye chart used to measure how well you see at various distances. The eye chart, known as Snellen s chart, is imprinted with block letters that line by line decrease in size, corresponding to the distance at which that… …   Medical dictionary

  • Eye chart, Snellen's — The familiar eye chart used to measure how well you see at various distances. Snellen s chart is imprinted with block letters that line by line decrease in size, corresponding to the distance at which that line of letters is normally visible. The …   Medical dictionary

  • Snellen chart — A Snellen chart is an eye chart used by eye care professionals and others to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862.DescriptionThe traditional Snellen chart… …   Wikipedia

  • Snellen fraction —    a ratio (such as 20/20 or 20/100) measuring the acuity (sharpness) of a person s eyesight for objects at a distance. The denominator (number after the slash) is the distance at which the detail of a letter on a standard test chart would… …   Dictionary of units of measurement

  • chart — 1. A recording of clinical data relating to a patient s case. 2. SYN: curve (2). 3. In optics, symbols of graduated size for measuring visual acuity, or test types for determining far or near vision. See …   Medical dictionary

  • Eye chart test — This test measures how well you see at various distances. The eye chart itself the usual one is called Snellen s chart is imprinted with block letters that line by line decrease in size, corresponding to the distance at which that line of letters …   Medical dictionary

  • Test, eye chart — This test measures how well you see at various distances. The eye chart itself the usual one is called Snellen s chart is imprinted with block letters that line by line decrease in size, corresponding to the distance at which that line of letters …   Medical dictionary

  • E Chart — An E Chart is an ophthalmological chart used to measure a patient s acuity for distant vision.UsesThis chart is useful for patients that are illiterate or too young to read but who can speak.It contains rows of the letter E in various kinds of… …   Wikipedia

  • Eye chart — NOTOC Infobox Laboratory equipment name = Eye chart caption = Typical Snellen chart used for visual acuity testing. acronym = other names = uses = Vision testing inventor = manufacturer = model = related = Snellen chart Landolt C Lea test Tibetan …   Wikipedia

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