1. Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
2. Department of Cellular and Structure Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
3. Department of Neurology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
4. Department of Ophthalmology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
5. South Texas Veterans Health Care System, San Antonio, Texas.