The impact of vision impairment on vision-related quality of life of patients with neovascular age-related macular degeneration

Abstract

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.