[1] Univ N Carolina, Sch Med, Chapel Hill, NC USA
[2] Univ N Carolina, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA
[3] Univ N Carolina, Chapel Hill, NC USA
[4] George Washington Univ, Sch Med & Hlth Sci, Washington, DC 20052 USA
[5] Univ N Carolina, Dept Ophthalmol, Chapel Hill, NC USA