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 (rho = 0.28-0.47) and measurements of
visual acuity (rho = 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
