DANISH MEDICAL BULLETIN

INTRODUCTION: Assessment of visual function can be a complex task and objective means of measurement of visual function do not always correlate with patients’ selfperceived visual abilities. The purpose of this study was to translate the visual function questionnaire (VFQ)-25 into Danish with particular focus on its use in patients with late age-related macular degeneration (AMD). MATERIAL AND METHODS: The translation was done in accordance with standard internationally adopted methods. This includes forward translation, back translation, examination of translation quality, and adjudication by bilingual speakers. We presented the questionnaire to 120 consecutive patients with exudative AMD referred to our department and to 25 healthy individuals. We tested the reliability of the Danish version by measuring test-retest reliability, estimated the internal consistency of the questionnaire (Cronbach’s α value) and analysed the discriminatory power (validity) of the questionnaire by comparing scores of patients with scores from control individuals without known eye disease. RESULTS: The translated questionnaire produced high testretest correlations (range 0.8-0.9), had a relatively high level of internal consistency (range 0.4-0.9) and a high discriminatory power. CONCLUSION: The Danish version of VFQ-25 produces acceptable values of validity and reliability in patients with AMD. Assessment of visual function can be a complex task and objective means for the measurement of visual function do not always correlate with the person’s self-perceived visual abilities [1]. For routine visual acuity assessment in daily clinical practice, the Snellen Visual Acuity Chart or the Early Treatment Diabetic Retinopathy Study (ETDRS) Chart is generally used [2]. These charts measure visual acuity from a distance of six or four meters, but little information is obtained about the visual ability needed to perform tasks requiring good vision at a closer distance. Despite these shortcomings of the Snellen and ETDRS charts, they remain widely used and accepted as primary outcome measurements of treatment efficacy [3, 4]. To compensate for these shortcomings, several questionnaires have been developed to provide a more detailed account of treatment efficacy and patient-perceived visual ability [1]. The Visual Function Questionnaire (VFQ) developed at the National Eye Institute, Bethesda, Maryland, USA, is one of the more widely used methods [5]. Initially, the questionnaire comprised 51 questions, but in response to clinicians’ feedback, it was reduced to 25 questions (VFQ-25), which made it more appropriate for use in daily clinical practice [6]. The questions included in the VFQ-25 were selected on the basis of extensive focus group interviews with several groups of patients with different eye diseases including age-related macular degeneration (AMD) [5, 7]. The questionnaire generates subscales for the following dimensions of vision-targeted, health-related quality of life: overall general health, overall general vision, problems because of ocular pain, difficulty with near-vision activities, difficulties with distance-vision activities, limitations in social function due to visual difficulties, mental health problems due to vision, role difficulties due to vision, dependency on others due to diminished vision, driving difficulties because of diminished vision, difficulties with colour vision and difficulties with peripheral vision. Each of the subscales is scored on a 0 to 100 scale in which 100 indicates the best possible and 0 the worst possible function. There are 14 optional items in a voluntary appendix (VFQ-39). The VFQ-25 has been extensively validated and has been translated into several different languages [812]. The purpose of this study was to translate the VFQ-25 (including the appendix – VFQ-39) into Danish with parDanish version of Visual Function Questionnaire-25 and its use in age-related macular degeneration Mette Sejer Sørensen, Susanne Andersen, Gitte Østerby Henningsen, Charlotte Thornby Larsen & Torben Lykke Sørensen