Visual impairment and vision‐related quality of life in the Early Manifest Glaucoma Trial after 20 years of follow‐up

PURPOSE: To determine the association between vision‐related quality of life (VRQOL) and levels of visual function loss in the Early Manifest Glaucoma Trial (EMGT). METHODS: Two hundred and fifty‐five patients were included in the EMGT between 1993 and 1997 and followed regularly by ophthalmic examinations. A Swedish translation of the National Eye Institute Visual Function Questionnaire 25 (NEI VFQ‐25) was self‐administered at several follow‐up visits until 2014. We analysed the association between Rasch‐calibrated NEI VFQ‐25 scores and visual function in the best eye at the final follow‐up visit. RESULTS: Ninety‐one per cent (233/255) of all participants completed the NEI VFQ‐25 at least once. In univariate logistic regression analysis, NEI VFQ‐25 scores were modestly associated with visual acuity (VA) (r (2) = 0.330, p < 0.001), visual field index (VFI) (r (2) = 0.200, p < 0.001) and perimetric mean deviation (MD) (r (2) = 0.193, p < 0.001). In multivariate analysis, VA and VFI together accounted for approximately 40% (r (2) = 0.380) of the NEI VFQ‐25 scores. NEI VFQ‐25 scores were significantly higher for patients with no visual impairment (mean 73 ± 22) than for visually impaired patients (mean 31 ± 15, p < 0.001). VFI worse than 50% or MD worse than −18 dB was significantly associated with low VRQOL scores (p < 0.001). CONCLUSIONS: Our results support the widespread, albeit arbitrary, use of a better‐eye visual field of <50% as an important threshold for a significant reduction in VRQOL.