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The largest letter on an eye chart often represents an acuity of 6/60 (20/200), the value that is considered "legally blind" in the US. Many individuals with high myopia cannot read the large E without glasses, but can read the 6/6 (20/20) line or 6/4.5 (20/15) line with glasses. By contrast, legally blind individuals have a visual acuity of 6/ ...
This classification traces its history to the early history of blind sport. There was a belief that those with vision impairment that was less severe had a competitive advantage over competitors who had more severe impairment. Classification was developed by the IBSA to insure more even competition across the different bands of visual acuity. [19]
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.
A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. [9] Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better ...
The chart was designed by Ian Bailey [5] and Jan E. Lovie-Kitchin at the National Vision Research Institute of Australia. [1] [3] They described their motivation for designing the LogMAR chart as follows: "We have designed a series of near vision charts in which the typeface, size progression, size range, number of words per row and spacings were chosen in an endeavour to achieve a ...
The World Health Organization classifies [1] [2] people with low vision as follows: 1. 6/18 (20/60) [0.5] to 6/60 (20/200) [1.0] 2. 6/60 (20/200) [1.0] to 3/60 (20/400) [1.3] 3. 3/60 (20/400) [1.3] to 1/60 (20/1200) [1.8] readings from left to right are in metres, feet and LogMAR values
The vision of infants under one month of age ranges from 6/240 to 6/60 (20/800 to 20/200). [4] By two months, visual acuity improves to 6/45 (20/150). By four months, acuity improves by a factor of 2 – calculated to be 6/18 (20/60) vision. As the infant grows, the acuity reaches the healthy adult standard of 6/6 (20/20) at six months. [5]
Vision (unaided) VA Visual acuity VA Dcc - VA Dsc Visual acuity with Distant chart with correctors Visual acuity with eye chart at Distant 20 feet (6 m) and with (cc: Latin cum correctore) correctors (spectacles); Dsc is without (sc: Latin sine correctore) correctors. See Visual_acuity#Legal_definitions: VA Nsc - VA Ncc