[1] FM Kirby Ctr Mol Ophthalmol, Philadelphia, PA USA
[2] Univ Penn, Scheie Eye Inst, Philadelphia, PA 19104 USA
[3] GE Global Res, Magnet Resonance Imaging Lab, Niskayuna, NY USA
[4] Albany Med Coll, Dept Neurol, Albany, NY 12208 USA
[5] Univ Penn, Dept Med, Philadelphia, PA 19104 USA