Validation of the Portuguese Version of the Quality of Life Impact of Refractive Correction Questionnaire (QIRC): Study on a Sample of Young Adults.

OBJETIVE: In this study, we aimed to perform the cross-cultural adaptation and psychometric evaluation of the Quality of Life Impact of Refractive Correction (QIRC) questionnaire for European Portuguese. METHODS: International guidelines for the adaptation of questionnaire-based assessment instruments were followed, and the study was conducted in two phases: 1) Cross-cultural adaptation, involving translation, back-translation, and pretesting for semantic equivalence; 2) Psychometric evaluation of the scale. A convenience sample was selected from secondary and higher education institutions. Reliability was assessed using Cronbach's alpha (α) and McDonald's omega (ω), while temporal stability was evaluated by the intraclass correlation coefficient (ICC). The evaluation of the instrument's dimensional structure was performed using exploratory factor analysis (EFA). RESULTS: The sample consisted of 373 students, aged between 16 and 35 years. Internal consistency was high (α=0.848 and ω=0.862) and temporal stability was considered excellent (ICC=0.951). We identified three factors (Difficulties and Concerns - 11 items; Comfort and Well-being - 7 items; and Function and Symptoms - 2 items), according to the EFA, which explained 66.82% of the total variance. Internal consistency was excellent for Difficulties and Concerns (α=0.970), good for Comfort and Well-being (α=0.830); and low for Function and Symptoms (α=0.253), the latter being composed of only two items. CONCLUSION: The results support the evaluation of the instrument's dimensional structure and reliability of the Portuguese version of the QIRC, adapted for European Portuguese. It is a suitable tool for assessing the impact of refractive correction on the quality of life among young populations in Portugal.