1. Iowa City Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa 2Department of Biomedical Sciences, Iowa State University, Ames, Iowa
2. Department of Veterinary Clinical Sciences, Iowa State University, Ames, Iowa
3. Iowa City Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa 4Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa
4. Iowa City Veterans Administration Center for the Prevention and Treatment of Visual Loss, Iowa City, Iowa