[1] Univ Illinois, Coll Med, Dept Ophthalmol & Visual Sci, Chicago, IL USA
[2] Univ Illinois, Sch Publ Hlth, Dept Epidemiol & Biostat, Chicago, IL USA
[3] King Khalid Eye Specialist Hosp, Vitreoretinal Div, Riyadh, Saudi Arabia
[4] Univ Illinois, Coll Med, Dept Med, Chicago, IL USA
[5] 1855 West Taylor St, M-C 648, Chicago, IL 60612 USA