The National Board of Examiners in Optometry (NBEO) administer a set of examinations (“National Boards”) that “assess the cognitive, psychomotor, affective, and communication skills that are essential for entry-level optometric practice.” All 50 states require the passing of National Boards before you can obtain a license to practice optometry. Part I is taken the spring of the third year, Part II is taken in December of the fourth year, and Part III is taken any time during your fourth year. Some schools and colleges of optometry require a student to pass specific portions of the National Boards in order to graduate; others have no such requirement. The Michigan College of Optometry requires that all students sit for the NBEO examinations (or the Canadian equivalent), but does not require passage of any part for purposes of graduation. States also differ on exactly which portions of National Boards need to be passed, and some states also require an additional state board exam or state law exam prior to granting a license.
For additional information on the National Boards, visit them at National Board of Examiners in Optometry®
For more information on what each state requires for licensing as well as licensing fees, look up Association of Regulatory Boards of Optometry (ARBO).