Aims: To determine whether the Visual Function Questionnaire-25 (VFQ) is a more accurate instrument for assessing vision related quality of life (VRQOL) than visual acuity (VA) in patients with diabetic retinopathy. To compare VRQOL between patients with non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR).
Methods: We administered the VFQ and Vision Preference Value Scale (VPVS) to 104 patients. With VPVS as the gold standard in our study, we used Pearson's correlation and multiple linear regression analysis to assess whether VFQ is a more accurate measure of VRQOL than VA. Spearman correlation coefficients were used to assess which VFQ subscales correlated strongly with VPVS. Patients with NPDR and PDR were compared using VFQ.
Results: The Pearson's correlation coefficient between VPVS and VFQ was 0.49 (P<0.01) and between VPVS and VA was 0.33 (P<0.01). In multivariable linear models, VFQ explained a higher proportion of the variance in VPVS than VA. The VFQ subscales with the strongest Spearman coefficients to VPVS scores were role differences, near activities, distance activities, mental function and dependence. In these subscales, patients with PDR vsNPDR suffered a 25-30 point loss (100-point scale).
Conclusions: VFQ is a superior measure of VRQOL for patients with diabetic retinopathy because it better captures mental and emotional aspects of the disease as well as visual function. Subjects with PDR vsNPDR suffer significant loss of VRQOL.