for me there were about 20 students, you view the class 1st things for an hour. then they talk to you about the school, financial aid, and the clinics for an hour or 2. then you there is a student q and a session where all proffesor people leave and you can ask 5 current students questions. then you eat lunch with professors (its possible you could be eating with the person interviewing you. i did through coincidence). after lunch you separate inter 3 time periods, 1 is a tour, 1 is an interview and 1 is a break. you'll do all 3. they ended it with cookies with profesors and the other interviewees. it gets done at 3-4 something like that.
for the interview there is one professor, and 1 current student. its not 2 intense but be prepared. you might find this useful
http://www.studentdoctor.net/schools/?view=optometry
it is closed file so your interviewers know nothing about you.
i had 330 OAT and about 3.60 GPA and i got in.
i wore a suit and tie and so did everyone else, so thats a safe bet.