"Give a thoughtful, candid analysis of your professional objectives, both long term and short term. Include the following: why you want to study optometry, how you first became interested in the profession, and how you envision your career in optometry."
Pulled that from the NECO admissions page. What seems to be the problem? Id suggest packing the essay with your opt related shadow/volunteering/work experience. Perhaps a fun anticdote of how you decided you wanted to stare at eyeballs for the next 40 years. Id keep it around a page single spaced.
just my two cents