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RW Massof; Psychometric Properties of Visual Functioning Self-Assessment Questionnaires . Invest. Ophthalmol. Vis. Sci. 2002;43(13):875.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To compare reliabilities and validities of the VF-14, VAQ, ADVS, and NEI VFQ-25 as measures of functional ability for a population of patients with bilateral visual impairments. Methods:Telephone interviews were conducted on 240 low vision patients prior to first visit at the low vision clinic. Two of the four questionnaires were administered to each subject resultling in 40 subjects per each of the 6 instrument pairings. Results:Rasch analysis was performed on each response matrix (120 subjects x n items) for each instrument. Person measure separation reliability ranged from 0.83 (VF-14) to 0.95 (VFQ-25) and item measure separation reliability ranged from 0.93 (ADVS) to 0.98 (VFQ-25 & VF-14). Based on distributions of mean square residuals for both person and item measures, the VF-14 had the strongest construct validity and the VFQ-25 had the weakest. Principal components analyses of residuals confirm a single construct governing item responses for the VF-14, ADVS, VAQ, and part 2 of the VFQ-25. Inter-instrument person measure correlations range from 0.62 to 0.85. Conclusion:All four instruments are valid and reliable. Confounding dimensions resulting from the mixing of response categories decrease the validity of the VFQ-25. All four instruments produce equivalent estimates of functional ability in the low vision population.
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