Purpose: To investigate the validity and reliability of the Greek Impact of Vision Impairment Questionnaire (IVI) and to explore the predictors of vision-related quality of life (VRQoL) in individuals with neovascular age-related macular degeneration (nAMD). Methods: About 191 patients completed the IVI and the SF-12 Health Survey, and were assessed on visual exams. A random group of 20 participants completed the IVI twice with a 2 weeks interval, to assess test-retest reliability. About 102 patients completed the IVI 1 year later in a follow-up examination. Rasch analysis was used to evaluate response category functioning, scale precision, unidimensionality, scale targeting and differential item functioning. Stepwise multiple linear regression analyses identified predictors of VRQoL. Results: Test-retest reliability of IVI items was calculated from 0.86 to 0.98. The six response categories were merged into four to figure out disordered thresholds. Rasch analysis concluded in three scales: Mobility and Independence, Reading and Accessing Information, and Emotional Wellbeing. Regarding convergent validity, the IVI scores had significant associations with SF-12 components (ρ = 0.28–0.47) and measurements of visual acuity (ρ = 0.39–0.66). Worse VRQoL at 1 year follow-up was correlated with decline in distance and near VA. Distance VA and the SF-12 components were common predictors for all three subscales. The duration of disease was a significant predictor for the emotional subscale. Conclusion: The Greek IVI was found to assess AMD patients’ perceptions of VRQoL in a valid, reliable and responsive to eyesight manner. VRQoL was mainly established by patients’ distance VA and mental health.
Effect of cataract surgery on quality of life for patients with severe vision impairment due to age-related macular degeneration
