Table 2 Characteristics of congenital colour vision defects (CCVD) reported compared with the findings of the current study

Africa

 This study

Zulu

CVTME

704/601

7–17

2.2

4.2

0.6

 Ugalahi et al. [18]

Nigerian

Ishihara, FM D-15

769/866

13.9 ± 1.9

2.3

3.8

0.9

 Tabansi et al. [19]

Nigerian

Ishihara

N/R

N/R

2.6

N/R

N/R

 Abah et al. [21]

Nigerian

Ishihara

149/178

5–17

1.5

N/R

N/R

 Woldeamanuel and Geta [23]

Ethiopian

Ishihara

844

7–18 (11.75 ± 2.5)

4.1

3.6

0.6

 Mulusew and Yilikal [24]

Ethiopian

Ishihara

1040

12 ± 2.43

4.2 (95% CI 2.98–5.42)

N/R

N/R

Asia/Middle East

 Ahsana et al. [5]

Iranian

Ishihara

1352/1302

N/R

N/R

8.73

1.69

 Reddy et al. [22]

Indian

Ishihara

841/788

10–15

1.9

1.71

0.814

 Rajavi et al. [26]

Iranian

Ishihara

1069/1081

7–12 (mean, 9.4 ± 1.7)

2.2% (95% CI 1.5–3)

3.5

1

 Niroula and Saha [2]

Chhetri

Ishihara

474/490

10–19

N/R

3.8

0

 Shrestha et al. [20]

Chhetri

Ishihara

1050/951

10.35 ± 2.75 M

10.54 ± 2.72 F

2.1

3.9

0

 Napaporn et al. [27]

Thai

Ishihara

3056

6–7

4.2

3.7

0.5

Europe

 Gallo et al. [28]

Italian

Ishihara

63 933

11–14

4.8

 Azizoğlu et al. [29]

Turkish

Ishihara

823

4–10

3.8

 Rose et al. [30]

Caucasian

Ishihara

131

5–18

5.3

 Birch and Platts [31]

Caucasian

Ishihara

258/255

3–11

N/R

6.6

0.4