VF-14 item specific responses in patients undergoing first eye cataract surgery: can the length of the VF-14 be reduced?

• Published in: British journal of ophthalmology Vol. 86; no. 8; pp. 885 - 891
• Main Authors: Friedman, D S, Tielsch, J M, Vitale, S, Bass, E B, Schein, O D, Steinberg, E P
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01.08.2002; BMJ; BMJ Publishing Group LTD; Copyright 2002 British Journal of Ophthalmology
• Subjects: Aged; Biological and medical sciences; Cataract - rehabilitation; Cataract Extraction; Cataracts; Chi-Square Distribution; Clinical Science; Disability Evaluation; Eye surgery; Female; Health care policy; Humans; Large print; Male; Medical personnel; Medical sciences; Patient satisfaction; Patients; Reading; Studies; Surgery; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the eye and orbit; Surveys and Questionnaires; Treatment Outcome; Vision, Ocular; Handicap; Human; Cataract; Questionnaire; Daily living; Item analysis; Eye disease; Reduction; Lens disease; Treatment; Length; Surgery; Anterior segment disease
• ISSN: 0007-1161; 1468-2079
• DOI: 10.1136/bjo.86.8.885

Aims: To report the item specific responses of the VF-14 in a population of patients undergoing cataract surgery in their first eye and to determine whether or not the VF-14 can be reduced without compromising its performance as an index of cataract related visual impairment. Methods: The item specific responses to the VF-14 were analysed before (771 patients) and 4 months after (552 patients) cataract surgery in one eye to determine if the VF-14 index can be reduced without compromising its performance. Patients studied were selected from a cross sectional longitudinal study of patients undergoing cataract surgery in 72 ophthalmologist's offices located in three metropolitan regions of the United States. Results: Pairwise correlations between items in the VF-14 were all less than 0.6, indicating that no items could be removed solely on the basis of redundancy. 10 items correlated moderately with change in trouble, and 11 correlated moderately with change in satisfaction (r >0.15) at 4 months after cataract extraction. Eleven items demonstrated an effect size >0.4 at 4 months. These 11 items were either important for detecting cataract related functional disability or for quantifying the extent to which cataract impaired function. Additionally, 11 items were needed to detect adequately individuals with functional impairment. Three items (recognising people, cooking, and reading large print) were less responsive to cataract extraction and were more strongly associated with ocular comorbidities. Conclusions: While previous reports indicate that the VF-14 can be significantly shortened, our analysis only justifies removing three items. While the resulting VF-11 has properties similar to the VF-14, the limited time savings do not justify altering this already validated instrument.