1 Ulverscroft Eye Unit, School of Psychology and Vision Sciences, University of Leicester, Leicester, UK.
2 General University Hospital of Larissa, Larissa, Greece.
3 The Karolinska Neuroimmunology and Multiple Sclerosis Centre, Department of Clinical Neurosciences, Karolinska University Hospital, Stockholm, Sweden.
4 Ulverscroft Eye Unit, School of Psychology and Vision Sciences, University of Leicester, Leicester, UK; Department of Neurology, Cooper University Health Care, Cooper Medical School of Rowan University, Camden, NJ 08103, USA. Electronic address: ig15@le.ac.uk.