Their interview day is fairly laidback. The acutal interview is the most formal part. I went toward the beginning of the application process, so it took awhile to get my acceptance back.
At the beginning of the day you go into the building and go up to the 3rd (I think) floor, above the clinic, to where the optometry classes and offices are. If you park in the parking structure, make sure you go all the way to the top, uncovered spaces so you don't get towed.
You get a folder and then meet some of the other people interviewing that day. I was surprised how many of us there were - maybe 8 or so. Then you have a little welcome session where you go around and say your name, where you're from, etc. and an interesting fact about yourself. Then they do a little powerpoint - make notes about questions on the power point, because that helped me in the interview when they asked me if I had any questions.
Then, you rotate through interviewing. It is an individual, closed file interview with two interviewers. Mine were both professors, one first year prof and one third year prof. The interview was fairly short, about 20 minutes, and remember it's closed file - so emphasize the awesome things about your school, accomplishments, and experiences!
You also get a tour of campus, talk to a student, and meet for a short interview with someone in the admissions office (very short, easy, and informal) and go over your file. Lastly, you all go over to the union for lunch. The lunch is very relaxed - the students all sit at one table and eat with a current student. The adults (your parents are allowed to come with) eat with the people in charge and the dean of admissions.
Overall impression - it's a nice school, the people are very friendly, and it's great that they have it set up so you can either start the summer before or put in 5 years if you have circumstances that warrant it. Bloomington, IN is a pretty safe place to be and the campus is gorgeous, however very large. They also have opportunities for research. The negatives are that their equipment isn't nearly as advanced and new as some other schools, and they don't give many scholarships. I come from a small school, so the size of the university was daunting, even though they claim that the opt school is fairly self-contained.