1. Department of Ophthalmology and Visual Sciences; John A. Moran Eye Center; Salt Lake City UT USA
2. Department of Neurology; University of Utah; Salt Lake City UT USA
3. Division of Epidemiology, Department of Internal Medicine; University of Utah; Salt Lake City UT USA
4. Department of Family and Preventive Medicine; University of Utah; Salt Lake City UT USA
5. Veterans Affairs Salt Lake City Health Care System; Salt Lake City UT USA