Snellen test

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Snellen test

[′snel·ən ‚test]
(medicine)
A test for visual acuity presenting letters, numbers, or letter E's in various positions, with the symbols varying in size; if the smallest are read at a distance of 20 feet (6 meters), vision is recorded as 20/20, or normal.
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23) In the Hong Kong study of chronic psychiatric patients, uncorrected DVI was defined as 20/40 or worse using the Snellen chart.
The material resources used were: school classrooms, Illiterate E Snellen Charts, tape measures, tissues (as eye patches), class lists and feedback forms--all readily available and inexpensive.
The subject maintained focus on a 6 x 6 matrix of 20/20 letters on the clinical, near, reduced Snellen chart at 40 cm (2.
I found that the amount of sphere needed to blur the Mizar-Alcor pair and the 20/20 line on the Snellen chart was almost identical.
For vision screening, the Snellen chart and automatic SS-3 instrument (Topcon, Japan) were used.
The DVLA say this corresponds to a score of between 6/9 and 6/12 on a visual test known as the Snellen chart.
Devised in 1863, the Snellen chart is shaped like a pyramid with a large "E" at the apex with smaller and smaller lines of letters below.
Younger and pre-literate children are tested with the Snellen chart, which substitutes pictures of common objects, such as a house or apple, for letters.
In the Accident and Emergency department, the examining doctor is likely to have a correctly placed and illuminated Snellen chart available and be able to get an accurate assessment of visual acuity in an elderly patient.
This is equivalent to a gain of almost two lines on a snellen chart, the tool typically used during eye exams.