1. Department of Neurology, Hospital Group Twente ZGT, Almelo, The Netherlands
2. Department of Neurology, Centre of Expertise for Parkinson and Movement Disorders, Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
3. Department of Ophthalmology, Radboud University Medical Centre, Nijmegen, The Netherlands
4. Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands