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Installation, Features, & Functions
Size Progressions
When multiple lines of descending size are in use, the line size display is that of the smallest line. The
standard progression has the following visual acuity sizes expressed as Snellen fractions:
Snellen
20/10
20/15
20/20
20/25
20/30
20/40
20/50
20/60
20/70
20/80
20/100
20/200
20/400
Another line size progression available in ClearChart 4 is the LogMAR progression. This progression
has proved useful in prescribing low vision magnification aids and permits a more precise method of
scoring visual acuity.
Snellen
20/10
20/12.5
20/16
20/20
20/25
20/32
20/40
20/50
20/63
20/80
20/100
20/125
20/160
20/200
20/250
20/320
20/400
When the LogMAR progression is being used, the line size display shows the Snellen value in the
lower right-hand corner with the LogMAR line size next to it.
24
Snellen(metric)
6/3.0
6/4.5
6/6.0
6/7.5
6/9.0
6/12.0
6/15.0
6/18.0
6/21.0
6/24.0
6/30.0
6/60.0
6/120
Snellen(metric)
6/3.0
6/3.8
6/4.8
6/6.0
6/7.5
6/9.5
6/12
6/15
6/19
6/24
6/30
6/38
6/48
6/60
6/76
6/96
6/120
(continued)
Snellen (decimal)
2.00
1.33
1.00
0.800
0.667
0.500
0.400
0.333
0.286
0.250
0.200
0.100
0.050
LogMAR
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
13795-101 Rev. J
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