Psychometric validation of the Taiwan Chinese version of the 25‐Item National Eye Institute Visual Functioning Questionnaire

Abstract

To evaluate the reliability and construct validity of a Taiwan Chinese version of the 25-Item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ 25) in patients with visual impairment. The NEI-VFQ 25 was translated and adapted into the Taiwan Chinese version. In total, 222 patients responded to the questionnaire. To examine reliability, Cronbach's alpha for each subscale was used as an index of internal consistency. Test-retest reliability was evaluated with intraclass correlation coefficients. Regarding construct validity, both convergent and discriminant validities were calculated by means of multi-trait analysis. Clinical validity was examined by correlation of clinical measurements and subscale scores and known-groups comparison. Finally, correlation between different subscales was examined to evaluate hypothetical relationship between subscales. Five patient groups were studied, each including participants with a single cause of visual impairment. Group 1 consisted of 53 cataract patients; group 2 included 51 subjects with glaucoma; group 3 included 36 subjects with age-related macular degeneration (ARMD); and group 4 included 48 subjects with diabetic retinopathy. Thirty-four individuals with uncorrected refractive error comprised the control group. NEI-VFQ scores (mean +/- SD) for the cataract, glaucoma, ARMD, diabetic retinopathy and control groups were: 73.5 +/- 17.1, 69.2 +/- 20.4, 62.3 +/- 23.7, 63.7 +/- 20.8 and 80.7 +/- 12.0, respectively. Item analysis revealed moderate data skewing. Cronbach's alpha coefficients of subscales ranged from 0.956 (mental health) to 0.964 (near activities). Intraclass correlation coefficients ranged from 0.41 (driving) to 0.846 (distance activities). All items passed the convergent and discriminant validity tests. Moderate correlations were detected between visual acuity and the 'general vision', 'distance activities' and 'near activities' subscales. Significant correlations were detected between visual field deficits and the vision associated subscales. This study revealed that the Taiwan Chinese version of the NEI-VFQ 25 is a valid and reliable instrument to measure vision-related quality of life in patients with visual impairment.