Some schools like NOVA and ICO will email you supp questions after they receive your application.
I got an email from NOVA on friday letting me know that optomcas will send them my app soon and gave me the questions they are going to ask.
Both are "about 500 word" essays
1) What specifically are your reasons for choosing to apply to Nova Southeastern University College of Optometry?
2) Professional school is very challenging. What experiences in your life and/or undergraduate career have prepared you for the rigors of optometry school?