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X. Wang, J. Dai, J. Zhu, H. Xu, F. Xue, R. Chu, X. Sun, R. Massof, L. Wang; Rasch Analysis of CLVQOL Validity and Reliability in Urban Chinese Population. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3153. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the validity and reliability of the Chinese version of Low Vision Quality-of-Life Questionnaire (CLVQOL) using Rasch analysis.
Sixty nine patients aged 6-85 years, with best corrected visual acuity in the better eye ranging from 20/20 to light perception, were interviewed by trained surveyors using the CLVQOL. Twenty five questions in the CLVQOL were designed to make up 4 subscales: Distance vision and mobility (S1), adjustment (S2), reading and fine work (S3), activities of daily living (S4). Each question had a 6-point rating scale, with 0 being most and 5 least impaired. Rating scores were subjected to Rasch analysis, using the Andrich rating scale model, for the entire questionnaire and for each subscale. Person measures for each patient, item measures for each question, threshold measures for each response category (rating), and model fit statistics were estimated. A correlation matrix of person measures between subscales was constructed and confirmatory factor analysis was performed on the matrix.
Estimated person measures ranged from -6.37 to 6.02 logits, with the mean 0.67±1.49, Infit Zstd -0.1±1.6, and reliability 0.94. Estimated item measures ranged from -0.83 to 0.70, with the mean 0.00±0.4, Infit Zstd -0.1±1.9, and reliability 0.89. Factor analysis showed that two factors were necessary and sufficient. Person measures for S3 and S4 were highly correlated along one factor and S1 and S2 loaded on the other factor, with the person measure for the questionnaire falling on the principal component. Threshold measures were ordered.
Our analyses show that the CLVQOL is a valid instrument measuring functional visual impairment for the targeted population. In agreement with results from other VFQs, our findings suggest that the instrument measures two functional vision dimensions, one related to reading or seeing details and the other related to mobility or other motor activities.
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