Cross-validation of the Tunisian version of the National Eye Institute Visual Function Questionnaire 25

The goal of our study was to create a cross-cultural adaptation of the questionnaire « National Eye Institute Visual Function Questionnaire » (NEI-VFQ-25) for the Tunisian population (Tu-VFQ-25) and to test its psychometric properties in a group of patients with chronic uveitis.

The study consisted of two steps. The first was translation of the NEI-VFQ-25 and its cross-cultural adaptation to the Tunisian dialect (Tu-VFQ-25) according to the guidelines of Beaton et al. The second step consisted of studying the psychometric properties of the Tu-VFQ-25. Enrolled patients, diagnosed with chronic uveitis, were interviewed face-to-face by two different investigators, followed by a telephone interview by the first investigator 48hours later. Feasibility, internal consistency and reproducibility of the Tu-VFQ-25 were then tested using statistical methods.

The mean time taken to administrate the questionnaire to each of the 45 patients was 11min 40 s (± 2min 24 s). Internal consistency was acceptable, with Cronbach's alpha coefficients above 0.7 except the "Ocular Pain" and "Driving" subscales (0.645 and 0.559 respectively). Inter-observer reliability was excellent, with intra-class correlation coefficients (ICC) ranging from 0.857 to 0.985 for all subscales. Test-retest reliability, assessed for 43 patients, was good to excellent, with ICC above 0.80 for all subscales except "General Vision," which had a value of 0.786.

As with previous versions, the Tu-VFQ-25 is an easy and reliable tool for assessing vision-related quality of life of Tunisian patients with chronic uveitis.