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At exactly 6 metres' distance from the patient, the letters on the 6/6 line shall subtend 5 minutes of arc (such that the individual limbs of the letters subtend 1 minute of arc), which means that the chart should be sized such that these letters are 8.73 mm tall and the topmost (6/60) "E" should be 87.3 mm tall.
An example of the Landolt C eye chart (also known as the Japanese eye chart). Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision, while the ETDRS chart is designed for use at 4 meters. [16]
In the expression 6/x vision, the numerator (6) is the distance in metres between the subject and the chart and the denominator (x) the distance at which a person with 6/6 acuity would discern the same optotype. Thus, 6/12 means that a person with 6/6 vision would discern the same optotype from 12 metres away (i.e. at twice the distance).
Near visual acuity or near vision is a measure of how clearly a person can see nearby small objects or letters.Visual acuity in general usually refers clarity of distance vision, and is measured using eye charts like Snellen chart, LogMAR chart etc. Near vision is usually measured and recorded using a printed hand-held card containing different sized paragraphs, words, letters or symbols.
The patient is seated at a 6-metre distance from the Snellen Chart. [3] The illumination in the testing room is at a comfortable level of brightness for an indoor setting [3] Trial frames fitted comfortably on the patient and occluder over left eye.
Back vertex distance BVP: Back vertex power CD: Centration distance C/D: Cup–disc ratio CF: Count fingers vision – state distance c/o or c.o. Complains of CT: Cover test c/u: Check up CW: Close work Δ: Prism dioptre D: Dioptres DC: Dioptres cylinder DNA: Did not attend DOB: Date of birth DS: Dioptres sphere DV: Distance vision DVD ...
Whereas for adults a small Snellen chart letter or number can be used. [1] Distance Targets (6m) Spotlight – In those patients with amblyopia a spotlight could be used. (Same as near targets). [1] Snellen chart – This is the most commonly used target when assessing a patient's far component of a cover test. [1]
First, the doctor should visually assess the eyes for deviations that could result from strabismus, extraocular muscle dysfunction, or palsy of the cranial nerves innervating the extraocular muscles. Saccades are assessed by having the patient move his or her eye quickly to a target at the far right, left, top and bottom. This tests for ...