[1] Univ Edinburgh, Div Clin Neurosci, Western Gen Hosp, Edinburgh EH4 2XU, Midlothian, Scotland
[2] Univ Edinburgh, Wellcome Trust Clin Res Facil, Edinburgh EH4 2XU, Midlothian, Scotland
[3] Univ Edinburgh, SFC Brain Imaging Ctr, Edinburgh EH4 2XU, Midlothian, Scotland
[4] Manchester Royal Eye Hosp, Dept Vitreoretinal Surg, Manchester, Lancs, England