Color discrimination was estimated using the Cambridge Colour Test (CCT) in 160 normal trichromats of four life decades, 20–59 years of age. For each age cohort, medians and tolerance limits of the CCT parameters are tabulated. Compared across the age cohorts (Kruskal–Wallis test), the Trivector test showed increases in the three vectors, Protan, Deutan, and Tritan, with advancing age; the Ellipses test revealed significant elongation of the major axes of all three ellipses but no changes in either the axis ratio or the angle of the ellipse major axis. Multiple comparisons (Mann–Whitney test) between the cohorts of four age decades () revealed initial benign deterioration of color discrimination in the decade, as an incremental loss of discrimination along the Deutan axis (Trivector test), and in the decade, as an elongation of the major axes of all three ellipses (Ellipses test).
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Trivector Test: Mean, Standard Deviation (SD), and Tolerance Limits of the Protan, Deutan, and Tritan Vectorsa for the 20–29 Year Old (Liverpool sample; ) vs. 18–30 Year Old (Brazil sample; ) [14]
Protan
Deutan
Tritan
Statistics
Liverpool
Brazil
Liverpool
Brazil
Liverpool
Brazil
Mean (SD)
42.3 (9.5)
43.2 (11.4)
42.2 (11.8)
47.3 (15.0)
54.9 (15.4)
67.7 (19.6)
Upper limit
61.7
69.3
66.4
82.4
86.4
113.4
Lower limit
22.9
25.2
18.1
24.7
23.4
37.3
in units.
Table 2.
Ellipses Test, Length of the Major Axisa: Mean, Standard Deviation (SD), and Tolerance Limits for the 20–29 Year Old (Liverpool sample; ) vs. 18–30 Year Old (Brazil sample; ) [14]
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Liverpool
Brazil
Liverpool
Brazil
Liverpool
Brazil
Mean (SD)
113.0 (26.3)
127.7 (35.8)
123.9 (27.4)
142.1 (38.7)
166.1 (44.6)
174.9 (47.7)
Upper limit
167.0
209.3
180.1
226.9
257.7
286.1
Lower limit
59.0
72.2
67.6
83.1
74.5
99.4
in units.
Table 3.
Ellipses test, Major-to-Minor Axis Ratio: Mean, Standard Deviation (SD), and Tolerance Limits for the 20–29 Year Old (Liverpool sample; ) vs. 18–30 Year Old (Brazil sample; ) [14]
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Liverpool
Brazil
Liverpool
Brazil
Liverpool
Brazil
Mean (SD)
1.4 (0.4)
1.6 (0.3)
1.4 (0.2)
1.6 (0.4)
2.0 (0.5)
2.2 (0.5)
Upper limit
2.1
2.4
1.9
2.4
3.0
3.4
Lower limit
0.7
1.1
0.9
1.0
1.1
1.3
Table 4.
Trivector Test: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits of the Protan, Deutan and Tritan Vectorsa for the , , , and Age Groups
Protan
Deutan
Tritan
Statistics
Median ()
40.0 (6.5)
40.5 (7.0)
41.5 (10.0)
46.0 (7.5)
40.5 (10.0)
38.5 (7.5)
46.0 (10.5)
46.0 (11.0)
53.0 (8.0)
58.0 (9.0)
64.0 (14.5)
65.0 (14.5)
Upper limit
64
64
77
82
69
65
80
127
95
169
130
159
Lower limit
23
23
26
26
26
23
26
26
26
23
27
33
in units.
Table 5.
Ellipses Test, Length of the Ellipse Major Axisa: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits, for the , , , and Age Groups
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Median ()
106.5 (15.5)
112.5 (15.0)
116.5 (19.5)
124.5 (30.0)
118.5 (20.5)
130.5 (20.0)
144.5 (28.0)
154.0 (34.5)
157.5 (35.5)
150.0 (29.0)
179.0 (49.5)
192.5 (59.5)
Upper limit
221
192
241
287
203
242
295
363
286
439
387
421
Lower limit
77
80
69
84
75
76
86
102
97
101
99
106
in units.
Table 6.
Ellipses Test, Major-to-Minor Axis Ratio: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits for the , , , and Age Groups
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Median ()
1.29 (0.17)
1.31 (0.20)
1.37 (0.19)
1.43 (0.31)
1.34 (0.15)
1.33 (0.23)
1.42 (0.22)
1.42 (0.19)
2.09 (0.36)
1.86 (0.36)
2.08 (0.50)
2.04 (0.46)
Upper limit
2.66
2.43
3.47
2.86
2.22
2.46
2.53
3.68
3.10
4.25
4.90
5.32
Lower limit
1.07
1.03
1.03
1.11
1.04
1.08
1.03
1.06
1.13
1.04
1.26
1.33
Table 7.
Ellipses Test, Angle of the Major Axis: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits for the , , , and Age Groups
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Median ()
66.7 (15.5)
80.0 (19.5)
81.6 (19.6)
76.2 (19.0)
87.4 (23.5)
83.5 (38.9)
90.2 (28.0)
81.4 (17.8)
95.5 (8.3)
97.9 (8.7)
96.0 (8.8)
96.1 (9.4)
Upper limit
158
174
172
168
179
178
179
175
161
130
129
109
Lower limit
6
11
3
20
0
8
0
30
52
69
58
69
Tables (7)
Table 1.
Trivector Test: Mean, Standard Deviation (SD), and Tolerance Limits of the Protan, Deutan, and Tritan Vectorsa for the 20–29 Year Old (Liverpool sample; ) vs. 18–30 Year Old (Brazil sample; ) [14]
Protan
Deutan
Tritan
Statistics
Liverpool
Brazil
Liverpool
Brazil
Liverpool
Brazil
Mean (SD)
42.3 (9.5)
43.2 (11.4)
42.2 (11.8)
47.3 (15.0)
54.9 (15.4)
67.7 (19.6)
Upper limit
61.7
69.3
66.4
82.4
86.4
113.4
Lower limit
22.9
25.2
18.1
24.7
23.4
37.3
in units.
Table 2.
Ellipses Test, Length of the Major Axisa: Mean, Standard Deviation (SD), and Tolerance Limits for the 20–29 Year Old (Liverpool sample; ) vs. 18–30 Year Old (Brazil sample; ) [14]
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Liverpool
Brazil
Liverpool
Brazil
Liverpool
Brazil
Mean (SD)
113.0 (26.3)
127.7 (35.8)
123.9 (27.4)
142.1 (38.7)
166.1 (44.6)
174.9 (47.7)
Upper limit
167.0
209.3
180.1
226.9
257.7
286.1
Lower limit
59.0
72.2
67.6
83.1
74.5
99.4
in units.
Table 3.
Ellipses test, Major-to-Minor Axis Ratio: Mean, Standard Deviation (SD), and Tolerance Limits for the 20–29 Year Old (Liverpool sample; ) vs. 18–30 Year Old (Brazil sample; ) [14]
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Liverpool
Brazil
Liverpool
Brazil
Liverpool
Brazil
Mean (SD)
1.4 (0.4)
1.6 (0.3)
1.4 (0.2)
1.6 (0.4)
2.0 (0.5)
2.2 (0.5)
Upper limit
2.1
2.4
1.9
2.4
3.0
3.4
Lower limit
0.7
1.1
0.9
1.0
1.1
1.3
Table 4.
Trivector Test: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits of the Protan, Deutan and Tritan Vectorsa for the , , , and Age Groups
Protan
Deutan
Tritan
Statistics
Median ()
40.0 (6.5)
40.5 (7.0)
41.5 (10.0)
46.0 (7.5)
40.5 (10.0)
38.5 (7.5)
46.0 (10.5)
46.0 (11.0)
53.0 (8.0)
58.0 (9.0)
64.0 (14.5)
65.0 (14.5)
Upper limit
64
64
77
82
69
65
80
127
95
169
130
159
Lower limit
23
23
26
26
26
23
26
26
26
23
27
33
in units.
Table 5.
Ellipses Test, Length of the Ellipse Major Axisa: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits, for the , , , and Age Groups
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Median ()
106.5 (15.5)
112.5 (15.0)
116.5 (19.5)
124.5 (30.0)
118.5 (20.5)
130.5 (20.0)
144.5 (28.0)
154.0 (34.5)
157.5 (35.5)
150.0 (29.0)
179.0 (49.5)
192.5 (59.5)
Upper limit
221
192
241
287
203
242
295
363
286
439
387
421
Lower limit
77
80
69
84
75
76
86
102
97
101
99
106
in units.
Table 6.
Ellipses Test, Major-to-Minor Axis Ratio: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits for the , , , and Age Groups
Ellipse 1
Ellipse 2
Ellipse 3
Statistics
Median ()
1.29 (0.17)
1.31 (0.20)
1.37 (0.19)
1.43 (0.31)
1.34 (0.15)
1.33 (0.23)
1.42 (0.22)
1.42 (0.19)
2.09 (0.36)
1.86 (0.36)
2.08 (0.50)
2.04 (0.46)
Upper limit
2.66
2.43
3.47
2.86
2.22
2.46
2.53
3.68
3.10
4.25
4.90
5.32
Lower limit
1.07
1.03
1.03
1.11
1.04
1.08
1.03
1.06
1.13
1.04
1.26
1.33
Table 7.
Ellipses Test, Angle of the Major Axis: Median, Half-Interquartile Range (), Upper and Lower Tolerance Limits for the , , , and Age Groups