ICO has more than 150 affiliated clinical sites in 47 states and four countries (Australia, Canada, China and the United Arab Emirates). Besides choosing the location, fourth-year students also can choose from a variety of settings, including OD/MD practices, private and group practices, military sites, Veterans Administration (VA) hospitals, community health centers and Indian health service clinics. Students are required to spend one quarter at the Illinois Eye Institute and two quarters at externship sites. On average, students encounter 1,600 total patient visits during their experience at ICO.