User Experiences Among Patients and Health Care Professionals Who Participated in a Randomized Controlled Trial of E-nergEYEze, a Vision-Specific eHealth Intervention to Reduce Fatigue in Adults With Visual Impairment: Mixed Methods Study - Manon HJ Veldman; Hilde PA van der Aa; Hans Knoop; Christina Bode; Ger HMB van Rens; Ruth MA van Nispen (JMIR Formative Research)