RR.2.4 Traditional Charts
The Traditional charts used in clinical practice are not standardized; they have an irregular progression of letter sizes and a variable number of characters per line. Measurement accuracy may further suffer from hidden errors that cannot be captured by any recording device, such as an inconsistent, non-standardized protocol, inaccurate viewing distance, inaccurate projector adjustment and contrast loss from room illumination. Therefore, the difference between two routine clinical measurements should not be considered significant, unless it exceeds 5 rows in the table (1 line on an ETDRS chart).
Table RR-1 contains many blank lines to make the vertical scale consistent with that used in Table RR-2. Notations within the same gray band are interchangeable for routine clinical use, since their differences are small compared to the clinical variability, which is typically in the order of 5 rows (1 ETDRS line).
Table RR-1. Reference Table for Use with Traditional Charts
|
DICOM
|
Notations for Clinical Use with Traditional Charts
|
Scales for statistics and graphical displays
|
|
Decimal Visual Acuity
|
|
Traditional scales
|
|
Linear Scales
|
|
|
Decimal
|
US
|
6 m
|
|
LogMAR
|
VAS
|
|
2.00 E+00
|
|
2.0
|
20/10
|
6/3
|
|
-0.30
|
115
|
|
1.91 E+00
|
|
|
|
|
|
-0.28
|
114
|
|
1.82 E+00
|
|
|
|
|
|
-0.26
|
113
|
|
1.74 E+00
|
|
|
|
|
|
-0.24
|
112
|
|
1.66 E+00
|
|
|
|
|
|
-0.22
|
111
|
|
1.60 E+00
|
|
1.6
|
20/12.5
|
6/3.8
|
|
-0.20
|
110
|
|
1.50 E+00
|
|
1.5
|
20/13
|
6/4
|
|
-0.18
|
109
|
|
1.45 E+00
|
|
|
|
|
|
-0.16
|
108
|
|
1.38 E+00
|
|
|
|
|
|
-0.14
|
107
|
|
1.30 E+00
|
|
1.3
|
20/15
|
6/4.5
|
|
-0.12
|
106
|
|
1.25 E+00
|
|
1.25
|
20/16
|
6/4.8
|
|
-0.10
|
105
|
|
1.20 E+00
|
|
1.2
|
20/17
|
6/5
|
|
-0.08
|
104
|
|
1.15 E+00
|
|
|
|
|
|
-0.06
|
103
|
|
1.10 E+00
|
|
1.1
|
20/18
|
6/5.5
|
|
-0.04
|
102
|
|
1.05 E+00
|
|
|
|
|
|
-0.02
|
101
|
|
1.00 E+00
|
|
1.0
|
20/20
|
6/6
|
|
0
|
100
|
|
9.55 E-01
|
|
|
|
|
|
0.02
|
99
|
|
9.00 E-01
|
|
0.9
|
20/22
|
6/66
|
|
0.04
|
98
|
|
8.70 E-01
|
|
|
|
|
|
0.06
|
97
|
|
8.30 E-01
|
|
|
|
|
|
0.08
|
96
|
|
8.00 E-01
|
|
0.8
|
20/25
|
6/7.5
|
|
0.10
|
95
|
|
7.50 E-01
|
|
0.75
|
20/26
|
6/8
|
|
0.12
|
94
|
|
7.20 E-01
|
|
|
|
|
|
0.14
|
93
|
|
7.00 E-01
|
|
0.7
|
20/28
|
6/8.7
|
|
0.16
|
92
|
|
6.60 E-01
|
|
0.66
|
20/30
|
6/9
|
|
0.18
|
91
|
|
6.30 E-01
|
|
0.63
|
20/32
|
6/9.5
|
|
0.20
|
90
|
|
6.00 E-01
|
|
0.6
|
20/33
|
6/10
|
|
0.22
|
89
|
|
5.75 E-01
|
|
|
|
|
|
0.24
|
88
|
|
5.50 E-01
|
|
|
|
|
|
0.26
|
87
|
|
5.25 E-01
|
|
|
|
|
|
0.28
|
86
|
|
5.00 E-01
|
|
0.5
|
20/40
|
6/12
|
|
0.30
|
85
|
|
4.80 E-01
|
|
|
|
|
|
0.32
|
84
|
|
4.57 E-01
|
|
|
|
|
|
0.34
|
83
|
|
4.37 E-01
|
|
|
|
|
|
0.36
|
82
|
|
4.17 E-01
|
|
|
|
|
|
0.38
|
81
|
|
4.00 E-01
|
|
0.4
|
20/50
|
6/15
|
|
0.40
|
80
|
|
3.80 E-01
|
|
|
|
|
|
0.42
|
79
|
|
3.60 E-01
|
|
|
|
|
|
0.44
|
78
|
|
3.50 E-01
|
|
|
|
|
|
0.46
|
77
|
|
3.33 E-01
|
|
0.33
|
20/60
|
6/18
|
|
0.48
|
76
|
|
3.20 E-01
|
|
0.32
|
20/63
|
6/19
|
|
0.50
|
75
|
|
3.00 E-01
|
|
0.3
|
20/66
|
6/20
|
|
0.52
|
74
|
|
2.90 E-01
|
|
0.28
|
20/70
|
6/21
|
|
0.54
|
73
|
|
2.75 E-01
|
|
|
|
|
|
0.56
|
72
|
|
2.63 E-01
|
|
|
|
|
|
0.58
|
71
|
|
2.50 E-01
|
|
0.25
|
20/80
|
6/24
|
|
0.60
|
70
|
|
2.40 E-01
|
|
|
|
|
|
0.62
|
69
|
|
2.30 E-01
|
|
|
|
|
|
0.64
|
68
|
|
2.20 E-01
|
|
|
|
|
|
0.66
|
67
|
|
2.10 E-01
|
|
|
|
|
|
0.68
|
66
|
|
2.00 E-01
|
|
0.2
|
20/100
|
6/30
|
|
0.70
|
65
|
|
1.90 E-01
|
|
|
|
|
|
0.72
|
64
|
|
1.82 E-01
|
|
|
|
|
|
0.74
|
63
|
|
1.74 E-01
|
|
|
|
|
|
0.76
|
62
|
|
1.66 E-01
|
|
0.17
|
20/120
|
6/36
|
|
0.78
|
61
|
|
1.60 E-01
|
|
0.16
|
20/125
|
6/38
|
|
0.80
|
60
|
|
1.50 E-01
|
|
0.15
|
20/130
|
6/40
|
|
0.82
|
59
|
|
1.45 E-01
|
|
|
|
|
|
0.84
|
58
|
|
1.38 E-01
|
|
|
|
|
|
0.86
|
57
|
|
1.30 E-01
|
|
0.13
|
20/150
|
6/45
|
|
0.88
|
56
|
|
1.25 E-01
|
|
0.125
|
20/160
|
6/48
|
|
0.90
|
55
|
|
1.20 E-01
|
|
0.12
|
20/170
|
6/50
|
|
0.92
|
54
|
|
1.15 E-01
|
|
|
|
|
|
0.94
|
53
|
|
1.10 E-01
|
|
|
|
|
|
0.96
|
52
|
|
1.05 E-01
|
|
|
|
|
|
0.98
|
51
|
|
1.00 E-01
|
|
0.1
|
20/200
|
6/60
|
|
1.00
|
50
|
|
9.55 E-02
|
|
|
|
|
|
1.02
|
49
|
|
9.00 E-02
|
|
|
|
|
|
1.04
|
48
|
|
8.70 E-02
|
|
|
|
|
|
1.06
|
47
|
|
8.30 E-02
|
|
0.083
|
20/240
|
6/72
|
|
1.08
|
46
|
|
8.00 E-02
|
|
0.08
|
20/250
|
6/75
|
|
1.10
|
45
|
|
7.50 E-02
|
|
|
|
|
|
1.12
|
44
|
|
7.20 E-02
|
|
|
|
|
|
1.14
|
43
|
|
7.00 E-02
|
|
|
|
|
|
1.16
|
42
|
|
6.60 E-02
|
|
0.065
|
20/300
|
6/90
|
|
1.18
|
41
|
|
6.30 E-02
|
|
0.063
|
20/320
|
6/95
|
|
1.20
|
40
|
|
6.00 E-02
|
|
0.06
|
20/330
|
6/100
|
|
1.22
|
39
|
|
5.75 E-02
|
|
|
|
|
|
1.24
|
38
|
|
5.50 E-02
|
|
|
|
|
|
1.26
|
37
|
|
5.25 E-02
|
|
|
|
|
|
1.28
|
36
|
|
5.00 E-02
|
|
0.05
|
20/400
|
6/120
|
|
1.30
|
35
|
|
4.80 E-02
|
|
|
|
|
|
1.32
|
34
|
|
4.60 E-02
|
|
|
|
|
|
1.34
|
33
|
|
4.40 E-02
|
|
|
|
|
|
1.36
|
32
|
|
4.20 E-02
|
|
|
|
|
|
1.38
|
31
|
|
4.00 E-02
|
|
0.04
|
20/500
|
6/150
|
|
1.40
|
30
|
|
3.80 E-02
|
|
|
|
|
|
1.42
|
29
|
|
3.60 E-02
|
|
|
|
|
|
1.44
|
28
|
|
3.50 E-02
|
|
|
|
|
|
1.46
|
27
|
|
3.33 E-02
|
|
|
|
|
|
1.48
|
26
|
|
3.20 E-02
|
|
0.032
|
20/630
|
6/190
|
|
1.50
|
25
|
|
3.02 E-02
|
|
0.03
|
20/650
|
6/200
|
|
1.52
|
24
|
|
2.90 E-02
|
|
|
|
|
|
1.54
|
23
|
|
2.75 E-02
|
|
|
|
|
|
1.56
|
22
|
|
2.63 E-02
|
|
|
|
|
|
1.58
|
21
|
|
2.50 E-02
|
|
0.025
|
20/800
|
6/240
|
|
1.60
|
20
|
|
2.40 E-02
|
|
|
|
|
|
1.62
|
19
|
|
2.30 E-02
|
|
|
|
|
|
1.64
|
18
|
|
2.20 E-02
|
|
|
|
|
|
1.66
|
17
|
|
2.10 E-02
|
|
|
|
|
|
1.68
|
16
|
|
2.00 E-02
|
|
0.02
|
20/1000
|
6/300
|
|
1.70
|
15
|
|
1.90 E-02
|
|
|
|
|
|
1.72
|
14
|
|
1.82 E-02
|
|
|
|
|
|
1.74
|
13
|
|
1.74 E-02
|
|
|
|
|
|
1.76
|
12
|
|
1.66 E-02
|
|
|
|
|
|
1.78
|
11
|
|
1.60 E-02
|
|
0.016
|
20/1250
|
6/380
|
|
1.80
|
10
|
|
1.50 E-02
|
|
0.015
|
20/1300
|
6/400
|
|
1.82
|
9
|
|
1.45 E-02
|
|
|
|
|
|
1.84
|
8
|
|
1.38 E-02
|
|
|
|
|
|
1.86
|
7
|
|
1.30 E-02
|
|
|
|
|
|
1.88
|
6
|
|
1.25 E-02
|
|
0.0125
|
20/1600
|
6/480
|
|
1.90
|
5
|
|
1.20 E-02
|
|
|
|
|
|
1.92
|
4
|
|
1.15 E-02
|
|
|
|
|
|
1.94
|
3
|
|
1.10 E-02
|
|
|
|
|
|
1.96
|
2
|
|
1.05 E-02
|
|
|
|
|
|
1.98
|
1
|
|
1.00 E-02
|
|
0.01
|
20/2000
|
6/600
|
|
2.00
|
0
|