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 ($20+,\dots ,50+$) revealed initial benign deterioration of color discrimination in the $40+$ decade, as an incremental loss of discrimination along the Deutan axis (Trivector test), and in the $50+$ 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; $\mathrm{N}=\mathrm{40}$) vs. 18–30 Year Old (Brazil sample; $\mathrm{N}=\mathrm{75}$) [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 ${10}^{-4}$${u}^{\prime}$${v}^{\prime}$ 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; $\mathrm{N}=\mathrm{40}$) vs. 18–30 Year Old (Brazil sample; $\mathrm{N}=\mathrm{75}$) [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 ${10}^{-5}$${u}^{\prime}$${v}^{\prime}$ 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; $\mathrm{N}=\mathrm{40}$) vs. 18–30 Year Old (Brazil sample; $\mathrm{N}=\mathrm{75}$) [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 ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits of the Protan, Deutan and Tritan Vectorsa for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Protan

Deutan

Tritan

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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 ${10}^{-4}$${u}^{\prime}$${v}^{\prime}$ units.

Table 5.

Ellipses Test, Length of the Ellipse Major Axisa: Median, Half-Interquartile Range ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits, for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Ellipse 1

Ellipse 2

Ellipse 3

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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 ${10}^{-5}$${u}^{\prime}$${v}^{\prime}$ units.

Table 6.

Ellipses Test, Major-to-Minor Axis Ratio: Median, Half-Interquartile Range ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Ellipse 1

Ellipse 2

Ellipse 3

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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 ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Ellipse 1

Ellipse 2

Ellipse 3

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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; $\mathrm{N}=\mathrm{40}$) vs. 18–30 Year Old (Brazil sample; $\mathrm{N}=\mathrm{75}$) [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 ${10}^{-4}$${u}^{\prime}$${v}^{\prime}$ 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; $\mathrm{N}=\mathrm{40}$) vs. 18–30 Year Old (Brazil sample; $\mathrm{N}=\mathrm{75}$) [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 ${10}^{-5}$${u}^{\prime}$${v}^{\prime}$ 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; $\mathrm{N}=\mathrm{40}$) vs. 18–30 Year Old (Brazil sample; $\mathrm{N}=\mathrm{75}$) [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 ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits of the Protan, Deutan and Tritan Vectorsa for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Protan

Deutan

Tritan

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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 ${10}^{-4}$${u}^{\prime}$${v}^{\prime}$ units.

Table 5.

Ellipses Test, Length of the Ellipse Major Axisa: Median, Half-Interquartile Range ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits, for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Ellipse 1

Ellipse 2

Ellipse 3

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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 ${10}^{-5}$${u}^{\prime}$${v}^{\prime}$ units.

Table 6.

Ellipses Test, Major-to-Minor Axis Ratio: Median, Half-Interquartile Range ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups

Ellipse 1

Ellipse 2

Ellipse 3

Statistics

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

$20+$

$30+$

$40+$

$50+$

Median ($\mathrm{IQR}/2$)

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 ($\mathrm{IQR}/\mathrm{2}$), Upper and Lower Tolerance Limits for the $\mathrm{20}+$, $\mathrm{30}+$, $\mathrm{40}+$, and $\mathrm{50}+$ Age Groups