chart(redirected from Snellen's chart)
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chart(chahrt) a record of data in graphic or tabular form.
Community Health Action Resource Team (Medspeak-UK)
Continuous Hyperfractionated Accelerated Radiotherapy Trial
chartnoun A formal document that includes relevant data, records, reports–eg radiology, pathology, of a person's medical Hx. See Bar chart, Hospital chart, Organized chart, Run chart, Subway chart verb To place orders, progress notes or data in a person's chart.
CHARTAcronym for Continuous Hyperfractionated Accelerated Radiotherapy, a form of treatment for non-small-cell lung cancer that has produced a significant improvement in survival compared with conventional radiotherapy.
Amsler chart One of a set of charts used to detect abnormalities in the central visual field which are so slight that they are undetected by the usual methods of perimetry. There are various patterns, each on a different chart, 10 cm square. One commonly used chart consists of a white grid of 5 mm squares on a black background. Each pattern has a dot in the centre, which the patient fixates. When fixated at a distance of 30 cm the entire chart subtends an angle of 20º. If there is any visual impairment (usually as a result of macular disease) it is demonstrated by the absence or irregularities of the lines (Fig. C6). Syn. Amsler grid. See age-related macular degeneration; metamorphopsia.
astigmatic fan chart A test pattern consisting of a semicircle of radiating black lines on a white background for determining the presence and the amount, as well as the axis of ocular astigmatism. If the chart resembles the 'clock face' type it is called an astigmatic dial or clock dial chart (Fig. C7).
Bailey-Lovie chart A visual acuity chart with letter sizes ranging from 6/60 (20/200) to 6/3 (20/10) in 14 rows of 5 letters. Each row has letters which are approximately 4/5 the size of the next larger letters and the letters in each row have approximately the same legibility (within ±10%). It is most useful with low vision patients. This is the most commonly used type of log MAR charts (Fig. C8). There is also a Bailey-Lovie Word Reading Chart for near vision. It is composed of words rather than letters. The size progression of each line is logarithmic. The typeface used is the lower case Times Roman customarily used in newspapers and books, and the range of sizes varies between 80-point and 2-point print (or the Snellen equivalent at 40 cm of 6/144 or 20/480 to 6/3.6 or 20/12, respectively). There are 20 such charts, each with a different set of words. See near visual acuity.
clock dial chart See astigmatic fan chart.
contrast sensitivity chart A chart designed to test contrast sensitivity. Such a test is useful with patients having low vision and in the early detection of diseases. Examples: Pelli-Robson chart; reduced contrast Bailey-Lovie near log MAR letter chart. See Teller acuity cards; Arden grating test; Vistech.
illiterate E chart Chart for carrying out a subjective visual acuity test on a person who cannot read. It consists of a graduated series of the Snellen letter E orientated in various directions which the subject must recognize. This procedure is sometimes called the 'E' test or 'E' game. See Teller acuity cards; 'E' game; Cardiff acuity test.
Landolt broken ring chart A visual acuity chart using a graduated series of Landolt rings in which the target thicknesses and gaps are equal to one-fifth of the outer diameter. The subject must indicate the orientation of the gap, which usually appears in one of four directions: right, left, up or down. This test is less subjective than the Snellen chart. Syn. Landolt C chart.
log MAR chart A visual acuity chart in which the rows of optotypes vary in a logarithmic progression. The multiplier of the geometric progression is usually equal to 1.2589 or 0.1 log unit. On one side of such a chart the rows of optotypes are usually labelled with the traditional Snellen notation. On the other side of each row visual acuity is labelled as the logarithm of the minimum angle of resolution (log MAR), which is the logarithm to the base 10 of the angular subtense of the stroke widths of the optotypes at a standard distance. See Bailey-Lovie chart; Glasgow acuity cards.
Pelli-Robson chart A contrast sensitivity chart consisting of eight lines of letters, all of the same size, subtending 3 degrees at a viewing distance of 1 m. On each line there are two groups, each containing three different letters; the letters in each group have the same contrast. The contrast of the different letters in each group decreases by a factor of 1/2 and the range of contrast varies between 100 and 0.6% in 16 steps. The subject is asked to read the letters starting with those of high contrast and continuing until two or three letters in one group are incorrectly named. The contrast threshold is represented by that of the previous group of letters. The chart gives the results in log contrast sensitivity. This test provides a measurement of contrast sensitivity at low to intermediate spatial frequencies depending upon the viewing distance. Syn. Pelli-Robson contrast sensitivity test.
Raubitschek chart A test target for determining the axis and the amount of astigmatism of the eye. It consists of two parabolic lines (known as wings) in an arrowhead pattern, parallel and closely spaced at one end, and each diverging from each other through a 90º angle at the other end. There are several methods of using this test. Syn. Raubitschek arrows; Raubitschek dial.
reduced contrast Bailey-Lovie near log MAR letter chart A set of 30 Bailey-Lovie charts designed to measure contrast sensitivity. Each chart has a different contrast, half of the charts contains the letters of the distance Bailey-Lovie chart and the other half contains the letters of the near Bailey-Lovie chart. All the charts have the same average reflectance and the contrast of the charts ranges from 0.95 to 0.0013%. The charts are presented to the subject in order of increasing contrast and the subject reads the letters from the largest to the smallest lines that they are able to. Threshold resolution in log min arc is determined for each of the 30 charts and a contrast sensitivity curve can thus be determined.
Snellen chart A visual acuity test using a graduated series of Snellen letters (or Snellen test types), in which the limbs and the spaces between them subtend an angle of one minute of arc at a specified distance. The letters are usually constructed so that they are 5 units high and 4 units wide, although some charts use letters that fit within a square subtending 5 minutes of arc at that distance. See Snellen acuity; Snellen fraction.
test chart A board externally illuminated, an internally illuminated transparent sheet, a slide for projection or a computer based system which projects optotypes or other tests used in the subjective determination of refraction. Syn. letter chart. See legibility; optotype.
|Table C2 Relationship between the Snellen fraction and the log MAR notation for distance visual acuity|
|Snellen fraction||log MAR|
|Table C3 Relationship between Snellen visual acuity and letter height at two viewing distances (the letter corresponding to an acuity of 6/6 subtends 5′ and the gap in the letter 1′)|
|Snellen acuity||letter height (mm)|
|(m)||(ft)||4 m||6 m|
Patient discussion about chart
Q. I’ve been planning to start a fitness regime center for some time now. What’s the best way to chart it out? I am the breadwinner in my family. I did a business that was earning me substantially well. It was a fitness equipment selling business. My business met with a loss last year and now I’ve been planning to start a fitness regime center for some time now. What’s the best way to chart it out and keep track of what I’ve done? I should not meet with the same loss again. Already my family is upset with me. So please help!
i hope it helped....
Q. I would like to compare old blood sugar and today´s blood sugar values or level. what is the difference?
i would like to help but i think i'll need a bit more information...