[1] Johns Hopkins Univ, Sch Med, Wilmer Eye Inst, Baltimore, MD 21205 USA
[2] Johns Hopkins Univ Hosp, Wilmer Ophthalmol Inst, Dana Ctr Prevent Ophthalmol, Baltimore, MD 21205 USA
[3] Wake Forest Sch Med, Dept Epidemiol, Winston Salem, NC USA
[4] Wake Forest Sch Med, Dept Ophthalmol, Winston Salem, NC USA