Translation, cross-cultural adaptation, and psychometric evaluation of the colour blind quality of life scale into Vietnamese

Background: The Colour Blind Quality of Life Scale (CBQoL) is a questionnaire developed to assess the quality of life of individuals with congenital colour vision deficiency (CVD). This study aimed to translate the English version of the CBQoL into Vietnamese and evaluate the validity and reliability of the Vietnamese version (CBQoL-VN). Methods: A forward-backward translation method was performed to produce the Vietnamese text. Content validity was assessed by six experts in vision care. Reliability testing involved 30 participants with congenital CVD, while discriminant validity was evaluated by comparing this group against 30 participants with normal colour vision. Results: Following expert consensus, two items were removed and one transportation-related item was added. The content validation index (CVI) values of 1.0 for relevance, clarity, and understandability indicated excellent content validity. Internal consistency was high, with a Cronbach's alpha of 0.95 for the full scale. Discriminant validity analysis showed that participants with congenital CVD scored significantly lower across all CBQoL-VN domains compared to those with normal colour vision. Conclusions: The modified CBQoL-VN is a valid and reliable instrument for assessing the quality of life of individuals with congenital CVD in the Vietnamese population.