[1] Brown Univ, Warren Alpert Med Sch, Providence, RI 02912 USA
[2] Brown Univ, Sch Publ Hlth, Providence, RI 02912 USA
[3] Brown Univ, Providence, RI 02912 USA
[4] Brown Univ, Div Ophthalmol, Warren Alpert Med Sch, Providence, RI 02912 USA
[5] Providence VA Med Ctr, Sect Ophthalmol, Providence, RI USA