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 |
||