1. Singapore Eye Research Institute, and
2. Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore
3. Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751, Singapore
4. School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
5. Stokes Veterans Administration Hospital, Cleveland, OH 44106, USA