Psychometric Properties of the Croatian Version of the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25)
Abstract Purpose: The purpose of study was to translate, adapt and validate the Croatian version of the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) in participants with visual impairment. This study also aims at evaluating the relationship between visual impairment and health-related quality of life (HRQoL).Methods: The prospective observational study was conducted at the University Hospital Centre Zagreb, Department of Ophthalmology. The sample consisted of 175 patients with four chronic ocular diseases: cataract, glaucoma, diabetic retinopathy and age-related macular degeneration (ARMD). The translation of the NEI VFQ-25 to Croatian was conducted following the standardized procedure. All participants underwent an ophthalmological examination and completed the NEI VFQ-25 and the Medical Outcomes Study Short Form-36 Questionnaire (SF-36). In order to assess the psychometric properties of the NEI VFQ-25 we calculated Cronbach's α coefficient, intraclass correlation coefficient (ICC), convergent and discriminant validity, as well as criterion and concurrent validity.Results: Results show high internal consistency (Cronbach α range 0.739-0.932) and high test-retest reliability (ICC 0.876-0.975) for all subscales. None of the items had failed either convergent or discriminant validity. Moderate to high Spearman's rho coefficients of correlations were found between best corrected visual acuity and 8 subscales in the NEI VFQ-25 (0.430<ρ<0.631). Moderate correlations were found between comparable domains in the NEI VFQ-25 and in the SF-36 questionnaire (p<0.01).Conclusion: The Croatian version of the NEI VFQ-25 has very good psychometric properties and can be a useful instrument for assessing vision-related quality of life in Croatian population with chronic ophthalmic diseases. The trial registration number: DRKS-ID DRKS00016751Date of registration in DRKS: 2019/02/15