[1] VA Palo Alto Hlth Care Syst, Ctr Hlth Care Evaluat, Menlo Pk, CA USA
[2] Stanford Univ, Sch Med, Dept Pathol, Palo Alto, CA 94304 USA
[3] VA Palo Alto Hlth Care Syst, Ophthalmol Serv, Palo Alto, CA 94304 USA
[4] Stanford Univ, Sch Med, Dept Ophthalmol, Palo Alto, CA 94304 USA