Impact of age-related macular degeneration in patients with glaucoma: understanding the patients' perspective

BACKGROUND The aim of the study is to measure the impact of age-related macular degeneration on vision-related activity limitation and preference-based status for glaucoma patients. DESIGN This was a cross-sectional study. PARTICIPANTS Two-hundred glaucoma patients of whom 73 had age-related macular degeneration were included in the research. METHODS Sociodemographic information, visual field parameters and visual acuity were collected. Age-related macular degeneration was scored using the Age-Related Eye Disease Study system. MAIN OUTCOME MEASURES The Rasch-analysed Glaucoma Activity Limitation-9 and the Visual Function Questionnaire Utility Index measured vision-related activity limitation and preference-based status, respectively. Regression models determined factors predictive of vision-related activity limitation and preference-based status. Differential item functioning compared Glaucoma Activity Limitation-9 item difficulty for those with and without age-related macular degeneration. RESULTS Mean age was 73.7 (±10.1) years. Lower better eye mean deviation (β: 1.42, 95% confidence interval: 1.24-1.63, P