Purpose: The purpose of this study was to develop the Chinese version of Ultra-Low Vision Visual Functioning Questionnaire-150 (ULV-VFQ-150) and evaluate its psychometric function.
Methods: A standardized procedure for the translation of ULV-VFQ-150 was carried out, including the forward translation, consistency check, back translation, back review, and coordination. Participants with ultra-low vision (ULV) were recruited for the questionnaire survey. Psychometric characteristics were evaluated using Rasch analysis based on Item Response Theory (IRT), and some items were revised and proofread accordingly.
Results: In total, 70 out of 74 responders completed the Chinese ULV-VFQ-150, of which 10 were excluded because their vision did not meet the criterion of ULV. Therefore, 60 valid questionnaires were analyzed (valid response rate = 81.1%). The average age of eligible responders was 49.0 years (standard deviation = 16.0), with 35% female subjects (21/60). The person measures (ability) ranged from -1.7 to +4.9 logits, and the item measures (difficulty) ranged from -1.6 to +1.2 logits. The mean value of item difficulty and personnel ability were 0.00 and 0.62 logits, respectively. The reliability index was 0.87 for items and 0.99 for persons, and the overall fit is good. The items conform to unidimensionality as indicated by principal component analysis of the residuals.
Conclusions: The Chinese version of ULV-VFQ-150 is a reliable questionnaire for evaluating both visual function and functional vision in people with ULV in China.
Translational relevance: The Chinese version of ULV-VFQ-150 is a new assessment of the visual function of people with ULV in China.