Snellen chart


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Snellen chart

(snĕl′ən)
n.
A chart for testing visual acuity, usually consisting of letters, numbers, or pictures printed in lines of decreasing size that a patient identifies from a fixed distance.

Snellen chart

Etymology: Hermann Snellen, Dutch ophthalmologist, 1834-1908
one of several charts used in testing visual acuity. Letters, numbers, or symbols are arranged on the chart in decreasing size from top to bottom.

Snellen chart

A wall chart developed by a Dutch ophthalmologist Hermann Snellen in the 19th century, which is still used today to measure visual acuity. It consists of 11 lines of block letters of decreasing size, which are to be read at a distance of 6 metres (20 feet). Per the British Standards Institution, only letters C, D, E, F, H, K, N, P, R, U, V, and Z should be used for the testing of vision based on the letters’ equal legibility. Snellen defined standard vision as the ability to recognise a letter (“optotype”) when it forms an angle of 5 arcminutes, which is “line nine” of the letters (“optotypes”) on the chart at 6 metres.

Snellen,

Hermann, Dutch ophthalmologist, 1834-1908.
Snellen chart - used to test visual acuity.
Snellen conventional reform implant
Snellen entropion forceps
Snellen eye implant
Snellen letters
Snellen operation
Snellen reform eye
Snellen sign - bruit heard on auscultation over the eye in a patient with Graves disease.
Snellen soft contact lens
Snellen suture
Snellen test types - square black symbols employed in testing the acuity of distant vision.
Snellen vectis
References in periodicals archive ?
Accommodative steadystate responses to high-contrast reduced Snellen chart stimuli having a luminance of 36 cd/[m.
33% of the study population showed a 2-line improvement on the Snellen chart after 1 month of treatment.
The patient's visual acuity was measured by Snellen chart as 20/20 in both eyes with refractive correction of -1.
CC is evaluated by Snellen chart to check the visual acuity in children >3 years old.
Since then, numerous different visual acuity tests have become available (see Figure 1), with the advent of the Snellen chart in the 19th century being an important landmark in the standardisation of measurement procedures.
Medium improvement was 3 lines on the standard Snellen chart for distant vision First residents required presceiption for near visual acuity alone.
On postoperative day 3, visual acuity on Snellen chart was 20/25 (with or without correction).
Their preoperative visual acuity on Snellen chart, anterior segment examination, Intraocular Pressure (IOP) by GAT (Goldmann Applanation tonometry), dilated fundus examination with indirect ophthalmoscope with peripheral indentation to rule out peripheral retinal breaks or retinal degenerations.
All the participants had visual acuity testing done by Snellen Chart, refraction by auto-refractors retinoscopy, orthoptic examination with deviation, slit lamp examination of anterior segment of eye, and fundoscopy with 90D lens.