[1] Alexandra Hosp, Dept Ophthalmol & Visual Sci, Singapore 159964, Singapore
[2] Natl Univ Singapore, Dept Ophthalmol, Yong Loo Lin Sch Med, Singapore 117548, Singapore
[3] Singapore Eye Res Inst, Singapore, Singapore
[4] Tan Tock Seng Hosp, Dept Ophthalmol, Singapore, Singapore