1. Department of Neuro-Ophthalmology, The National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
2. Department of Neuro-Ophthalmology, Moorfields Eye Hospital, London EC1V 2PD, UK
3. The Medical Eye Unit, St Thomas’ Hospital, London SE1 7EH, UK
4. Department of Neuro-Radiology, King’s College Hospital, London SE5 9RS, UK