[1] Natl Univ Singapore, Dept Community Occupat & Family Med, Singapore 117597, Singapore
[2] Singapore Eye Res Inst, Singapore, Singapore
[3] Inst Ophthalmol, London, England
[4] Singapore Natl Eye Ctr, Singapore, Singapore
[5] Natl Univ Singapore Hosp, Dept Ophthalmol, Singapore, Singapore
[6] Univ Sydney, Westmead Millenium Ins, Ctr Vis Res, Westmead, NSW 2145, Australia
[7] Univ Melbourne, Ctr Eye Res Australia, Melbourne, Vic, Australia