[1] Univ Ulsan, Coll Med, Asan Med Ctr, Dept Ophthalmol, Seoul 05505, South Korea
[2] Dankook Univ, Coll Med, Dankook Univ Hosp, Dept Ophthalmol, Cheonan 31116, South Korea
[3] Univ Ulsan, Coll Med, Asan Med Ctr, Clin Res Ctr,Asan Inst Life Sci, Seoul 05505, South Korea
[4] Univ Ulsan, Coll Med, Asan Med Ctr, Dept Clin Epidemiol & Biostat, Seoul 05505, South Korea