Cross-cultural validation of the National Eye Institute Visual Function Questionnaire

PURPOSE: To assess the native and the previously Rasch-modified National Eye Institute Visual Function Questionnaire (NEI VFQ) scales in a Chinese population.

SETTING: Eye Hospital of Wenzhou Medical University, Wenzhou, China.

DESIGN: Questionnaire development.

METHODS: Patients on the waiting list for cataract surgery completed the 39-item NEI VFQ (NEI VFQ-39). Rasch analysis was performed in 3 steps as follows: (1) Assess the psychometric properties of the original NEI VFQ. (2) Reassess the previously proposed Rasch-modified NEI VFQ scales by Pesudovs et al. (2010) in Chinese populations. (3) Compare the scores of previously recommended scales of the NEI VFQ with new Rasch-modified scales of the same questionnaire using Bland-Altman plots.

RESULTS: Four hundred thirty-five patients (median age 70 years; range 35 to 90 years) completed the NEI VFQ-39. Response categories for 4 question types were dysfunctional and therefore repaired. The original NEI VFQ-39 and NEI VFQ-25 showed good measurement precision. However, both versions showed multidimensionality, misfitting items, suboptimum targeting, and nonfunctioning subscales. Using the previously proposed Rasch-modified scales of the NEI VFQ yielded valid measurement of each construct in the 39-item and 25-item questionnaire. Comparison between the earlier proposed NEI VFQ scales and the new versions developed in this population showed good agreement.

CONCLUSIONS: The original NEI VFQ was once again found to be flawed. The previously proposed Rasch-analyzed versions of the NEI VFQ and the new Chinese versions showed good agreement.