1. From the Centre for Eye Research Australia (M.L.B., J.J.W., T.Y.W.), University of Melbourne, Victoria, Australia; the Department of Neurology (M.L.B., P.J.H.), Royal Melbourne Hospital, Victoria, Australia; the Centre for Vision Research (J.J.W.), University of Sydney, Sydney, Australia; and the Singapore Eye Research Institute (T.Y.W.), National University of Singapore, Singapore.