Development and validation of the 40-item Glaucoma Visual Functioning Questionnaire

• Published in: British journal of ophthalmology Vol. 107; no. 8; pp. 1086 - 1091
• Main Authors: Huang, Haishun, Lin, Junxiong, Luo, Man, Li, Zhidong, Zhu, Yingting, Han, Jiaxu, Jin, Ling, Li, Yiqing, Zhuo, Yehong
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01.08.2023; BMJ Publishing Group LTD; BMJ Publishing Group
• Subjects: Blindness; Clinical Science; Cross-Sectional Studies; Diabetes; Diabetic retinopathy; Eye diseases; Focus groups; Glaucoma; Glaucoma - diagnosis; Humans; Laboratories; Ophthalmology; Patients; Quality of Life; Questionnaires; Rehabilitation; Reproducibility of Results; Sickness Impact Profile; Strabismus; Surveys and Questionnaires; Validity; Vision; Vision Disorders - diagnosis; Visual impairment; China; Glaucoma; Vision; Rehabilitation
• ISSN: 0007-1161; 1468-2079; 1468-2079
• DOI: 10.1136/bjophthalmol-2021-320985

AimsTo evaluate the psychometric properties of a newly designed questionnaire, the 40-item Glaucoma Visual Functioning Questionnaire (GVFQ-40), in a Chinese sample to capture the visual ability of patients with glaucomatous vision impairment in five domains.MethodsEighty-four glaucoma suspects (controls) and 270 glaucoma patients were recruited from the Glaucoma Clinic at Zhongshan Ophthalmic Centre in this cross-sectional, observational study. All subjects completed two questionnaires during routine clinical visits: the GVFQ-40 and the validated National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25). The discriminant, criterion-related and construct validity of the GVFQ-40 were assessed. A subset of subjects completed the GVFQ-40 twice, with an interval of 7–21 days, to determine test–retest reliability.ResultsDomain-specific and total GVFQ-40 scores were significantly higher (worse visual ability) in glaucoma patients than in controls (all p<0.001). All pairwise subgroup comparisons were statistically significant except for the ‘mobility’ domain comparison between the mild visual field loss and control groups (p=0.189). Significant differences between these two groups were observed in only 2 of the 12 dimensions on the NEI VFQ-25. The GVFQ-40 results demonstrated strong correlations with better-eye mean deviation and Visual Field Index (glaucoma severity measures). Exploratory factor analysis tended to confirm a three-domain structure. Test–retest intraclass correlation coefficients were higher than 0.927 for domain-specific and total GVFQ-40 scores.ConclusionsThe GVFQ-40 possesses good validity and reliability. It can be used to evaluate the impact of glaucomatous damage on visual ability and has potential in the evaluation of intervention efficacy.Trial registration numberNCT04722861.